Diagnostic Aids

Perform this test only when instructed by QUICK TEST, or when directed by TEST A, TEST C, TEST DC, TEST PA or TEST PB.

This test is intended to diagnose only the following systems or components:

IRCM (Battery voltage and all relays)
Harness circuits (VBAT, VPWR, Key PWR, PWR GND, EDF circuit, FP circuit, HEDF circuit, A/C circuit and WAC circuit)
ECA
A/C Demand Switch Input

To prevent replacing good components, be aware that the following non-EEC related components or systems may be at fault:

Fuel lines or fuel filters
Contaminated fuel
Fuel pump
Ignition switch, battery cables and ground straps
Alternator and voltage regulator
A/C clutch or A/C demand switch
Cooling fan motor

3.0L PFI: IRCM TEST PIN WIRE COLOR I.D.

Application	Wire Color
Pin 1 (PTF)	Brown/Orange
Pin 2 (PTF)	Brown/Orange
Pin 3 (PTR)	Brown/Yellow
Pin 4 (PTR)	Brown/Yellow
Pin 5 (PTP)	Pink/Black
Pin 6 (PTF)	Black/Orange
Pin 7 (PTF)	Black/Orange
Pin 8 (BATT +)	Yellow
Pin 12 (PT/FPR)	Black/Orange
Pin 13 (KEY PWR)	Red/Light Green
Pin 14 (EDF)	Tan/Orange
Pin 15 (PWR GND)	Black/Light Green
Pin 16 (PWR GND)	Black
Pin 17 (HEDF)	Pink
Pin 18 (FP)	Tan/Light Green
Pin 21 (ACCS)	Pink/Light Blue
Pin 22 (WAC)	Red
Pin 23 (PTAC)	Black/Yellow
Pin 24 (VPWR)	Red

3.0L SPFI-MA AXODE: IRCM TEST PIN WIRE COLOR ID

Application	Wire Color
Pin 1 (PT/EDF)	Brown/Orange
Pin 2 (PT/EDF)	Brown/Orange
Pin 3 (PTF)	Dark Blue
Pin 4 (PTF)	Dark Blue
Pin 5 (PTP)	Pink/Black
Pin 6 (PT/HEDF)	Black/Orange
Pin 7 (PT/HEDF)	Black/Orange
Pin 8 (BATT +)	Yellow
Pin 12 (PT/FPR)	Black/Orange
Pin 13 (KEY PWR)	Red/Light Green
Pin 14 (EDF)	Tan/Orange
Pin 15 (PWR GND)	Black/Light Green
Pin 16 (PWR GND)	Black
Pin 17 (HEDF)	Light Green/Purple
Pin 18 (FP)	Tan/Light Green
Pin 21 (ACCS)	Black/Light Blue
Pin 22 (WAC)	Pink/Yellow
Pin 23 (PTAC)	Black/Yellow
Pin 24 (VPWR)	Red

3.0L SPFI-MA SHO: IRCM TEST PIN WIRE COLOR I.D.

Application	Wire Color
Pin 1 (PT/EDF)	Black/Orange
Pin 2 (PT/EDF)	Black/Orange
Pin 3 (PTF)	Brown/Orange
Pin 4 (PTF)	Brown/Orange
Pin 5 (PTP)	Pink/Black
Pin 8 (BATT +)	Yellow
Pin 10 (PT/LFP)	White/Red
Pin 11 (H/FP)	Light Blue/Orange
Pin 12 (PT/WAC)	Black/Orange
Pin 13 (KEY PWR)	Red/Light Green
Pin 14 (EDF)	Tan/Orange
Pin 15 (PWR GND)	Black/Light
Pin 16 (PWR GND)	Black
Pin 18 (L/FP)	Tan/Light Green
Pin 21 (ACCS)	Black/Light Blue
Pin 22 (WAC)	Red
Pin 23 (PTAC)	Black/Yellow
Pin 24 (VPWR)	Red

Fig 1: ECA & IRCM Connectors

Fig 2: IRCM Circuit Schematic (3.0L SPFI-MA AXODE)

Fig 3: IRCM Circuit Schematic (3.0L PFI Probe)

Fig 4: IRCM Circuit Schematic (3.0L SPFI-MA SHO)

1) Check Battery Supply Voltage With Key On Engine Off (KOEO), set DVOM on 20-volt scale. Measure voltage across battery terminals. If reading is less than 10.5 volts, service or replace discharged battery. If reading is 10.5 volts or more, go to next step.

2) Check Battery Ground With KOEO, set DVOM on 20-volt scale. Measure voltage between negative battery terminal and SIG RTN circuit in self-test connector. If reading is less than .5 volt, go to step 6). If reading is .5 volt or more, go to next step.

3) Isolating Ground Fault Turn ignition off. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box and connect ECA. Turn ignition on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between negative battery terminal and test pins No. 40 and 60. If each voltage reading is .5 volt or more, repair open ground circuit. Remove breakout box and repeat QUICK TEST. If both readings are less than .5 volt, go to next step.

4) ECA Ground Fault Isolation Turn ignition off and wait 10 seconds. With breakout box installed and ECA connected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and test pins No. 40 and 60. If each resistance is 5 ohms or more, replace ECA. Remove breakout box and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

5) Check Continuity Of SIG RTN Circuit Turn ignition off and wait 10 seconds. With breakout box and ECA disconnected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and SIG RTN circuit at self-test connector. If reading is less than 5 ohms, system is okay. Remove breakout box and reconnect ECA. Repeat QUICK TEST. If reading is 5 ohms or more, repair open SIG RTN circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

6) Measure Voltage & Ground To IRCM Turn ignition off and disconnect IRCM. Set DVOM on 20-volt scale. Measure voltage between pin No. 8 and pin No. 15 at IRCM vehicle harness connector. If voltage is greater than 10.5 volts, go to next step. If voltage is not greater than 10.5 volts, go to step 9).

7) Check Key Power To IRCM With ignition off, disconnect IRCM and set DVOM on 20-volt scale. With KOEO, measure voltage between pins No. 13 (+) and 15 (-) at IRCM vehicle harness connector. If reading is less than 10.5 volts, repair open between pin No. 13 and ignition switch. Reconnect IRCM and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

8) Check Continuity Of VPWR Circuit Turn ignition off. Disconnect IRCM and ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pins No. 37 and 57 at breakout box to pin No. 24 at IRCM vehicle harness connector. If reading is 5 ohms or more, repair open in VPWR circuit. Remove breakout box. Reconnect IRCM and repeat QUICK TEST. If reading is less than 5 ohms, replace IRCM. Remove breakout box and reconnect all components. Repeat QUICK TEST.

9) Check Continuity Of Power Ground To IRCM With ignition off and IRCM disconnected, set DVOM on 200-ohm scale. Measure resistance between negative battery terminal and IRCM harness connector pin No. 15. If resistance is 5 ohms or more, repair open in ground circuit to IRCM harness connector pin No. 15. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is less than 5 ohms, repair open in battery positive to pin No. 8 of IRCM harness connector. Reconnect IRCM and repeat QUICK TEST.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 9) to step 11). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

11) Check POWER-To-PUMPS Circuit Voltage With KOEO, locate and disconnect fuel pump(s). Set DVOM on 20-volt scale. Measure voltage between CHASSIS GROUND and POWER-to-PUMP circuit at fuel pump vehicle harness connector while cranking engine. If reading is 8.0 volts or more, service electric fuel pump system. If reading is less than 8.0 volts, go to next step.

12) Check POWER-To-PUMP Circuit Continuity With ignition off and DVOM on 200-ohm scale, disconnect IRCM and fuel pump(s). Measure resistance between IRCM harness connector pin No. 5 and POWER-to-PUMP circuit at harness connector at fuel pump(s). If reading is less than 5 ohms, go to next step. If reading is 5 ohms or more, repair open in POWER-to-PUMP circuit. Reconnect all components and repeat QUICK TEST.

13) Check Power To IRCM With ignition off and IRCM disconnected, set DVOM on 20-volt scale. Measure voltage between pin 12 (also pin 10 for 3.0L SHO) at IRCM vehicle harness connector and battery negative terminal. If voltage is greater than 10.5 volts, replace IRCM. Reconnect all components and rerun QUICK TEST. If voltage is less than 10.5 volts, repair open circuit in POWER-to-IRCM circuit. Reconnect all components and rerun QUICK TEST.

14) Check POWER-To-PUMP Circuit For Shorts To Power With ignition off and DVOM on 200-k/ohm scale, disconnect IRCM and fuel pump(s). Measure resistance between pin No. 5 and pin No. 24 at IRCM harness connector. Measure resistance between pin No. 5 at IRCM harness connector and battery positive terminal. If all readings are 10 k/ohms or more, replace IRCM; reconnect fuel pump and repeat QUICK TEST. If any reading is less than 10 k/ohms, repair short circuit. Reconnect all components and attempt to start vehicle. If vehicle starts, repeat QUICK TEST. If vehicle does not start, replace IRCM and repeat QUICK TEST.

15) Code 83/557 Or 87/556: Check Continuity Of Fuel Pump Circuit Code 83/557 or 87/556 indicates voltage output for the high or low fuel pump circuit did not change when activated during KOEO SELF-TEST. Possible causes for this fault are as follows:

Open or grounded fuel pump circuit
Open or grounded ECA driver
Disconnected or open solenoid

Turn ignition off. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM and set DVOM on 200-ohm scale. Perform appropriate procedure listed as follows:

Code 87/556 Or 83/557 (All Models Except 3.0L SHO) - Measure resistance between test pin No. 22 at breakout box and pin No. 18 at IRCM vehicle harness connector.
Code 87 (3.0L SHO) - Measure resistance between test pin No. 41 at breakout box and pin No. 11 at IRCM vehicle harness connector.

If resistance is 5 ohms or more, repair open in fuel pump circuit. Remove breakout box. Reconnect all components and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

16) Check Fuel Pump Circuit For Shorts To Power & Ground With ignition off, install breakout box. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Perform the following test as appropriate:

Code 87/556 Or 83/557 (All Models Except 3.0L SHO) - Measure resistance between test pin No. 22 and test pins No. 37, 57 and battery positive terminal. Measure resistance between test pins No. 22 and test pins No. 40, 60 and battery negative terminal.
Code 87/556 (3.0L SHO) - Measure resistance between test pin No. 41 and pins No. 37, 57 and battery positive terminal. Measure resistance between test pin No. 41 and test pins No. 40, 60 and battery negative terminal.

If all readings are 10 k/ohms or more, go to next step. If any reading is less than 10 k/ohms, repair fuel pump(s) short circuit to power or ground. Remove breakout box and reconnect all components. Repeat QUICK TEST. If Code 83/557 or 87/556 is still present, go to next step.

17) Check Fuel Pump Relay Coil Resistance Turn ignition off. Disconnect IRCM and set DVOM on 200-ohm scale. Disconnect ECA and install breakout box. Measure resistance of IRCM between pins No. 18 and 24, or pins No. 11 and 24. If resistance is 65-100 ohms, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST. If resistance is NOT 65-100 ohms, replace IRCM. Remove breakout box and reconnect all components. Repeat QUICK TEST.

18) No Fan Operation Turn ignition off. Disconnect IRCM and set DVOM on 20-volt scale. Perform the following test as appropriate:

3.0L SPFI-MA AXODE - Measure voltage between battery negative terminal and IRCM vehicle harness connector pin No. 1, 2, 6 & 7.
3.0L SPFI-MA SHO - Measure voltage between battery negative terminal and IRCM vehicle harness connector pin No. 1.
All Others - Measure voltage between battery negative terminal and IRCM vehicle harness connector pin No. 3 and 4.

If all readings are 10.5 volts or more, go to next step. If any reading is less than 10.5 volts, service open in battery power circuit. Reconnect IRCM and recheck system operation.

19) Check Fan Motor Operation Turn ignition off and disconnect IRCM connector. Perform the following test as appropriate:

3.0L SPFI-MA SHO - Install a jumper wire between IRCM harness connector pins No. 1 and 3.
All Others - Install a jumper wire between IRCM harness connector pins No. 3 and 6.

If cooling fan does not run, go to step 21). If cooling fan runs, go to next step (3.0L Probe), or go to step 25) (all others).

20) Check Fan Motor Operation Turn ignition off. Disconnect IRCM. Install a jumper between pins No. 3 and 2 at IRCM vehicle harness connector. If fan does not run, go to step 23). If fan runs, go to step 25).

21) Measuring Battery Voltage Supply At The Fan With The IRCM By-Passed With ignition off, disconnect cooling fan and IRCM. Perform the following test as appropriate:

3.0L SPFI-MA SHO - Install a jumper wire between IRCM harness connector pins No. 1 and 3.
All Others - Install a jumper wire between IRCM harness connector pins No. 3 and 6.

Set DVOM on 20-volt scale and measure voltage at cooling fan harness connector. If reading is less than 8.0 volts, go to next step. If reading is 8.0 volts or more, replace cooling fan motor. Reconnect IRCM and re-evaluate symptom.

22) Check Cooling Fan Ground Circuit Turn ignition off. Disconnect cooling fan and IRCM. Perform the following test as appropriate:

3.0L SPFI-MA SHO - Install a jumper wire between IRCM harness connector pins No. 1 and 3.
All Others - Install a jumper wire between IRCM harness connector pins No. 3 and 6.

Set DVOM on 20-volt scale. Measure voltage between positive terminal at cooling fan harness connector and battery negative terminal. If reading is 8 volts or more, repair open in ground circuit to fan. After repairs, reconnect IRCM and re-evaluate symptom. If reading is less than 8 volts, repair open in POWER-to-FAN circuit from IRCM vehicle harness connector to cooling fan vehicle harness connector. Reconnect all components and recheck system operation.

23) Measure Battery Voltage Supply At The Fan With The IRCM By-Passed Turn ignition off. Disconnect cooling fan and IRCM. Install a jumper wire between pins No. 2 and 3 at IRCM vehicle harness connector. Set DVOM on 20-volt scale. Measure voltage at cooling fan vehicle harness connector. If voltage is greater than 8 volts, replace fan motor. Reconnect IRCM and recheck system operation. If voltage is less than 8 volts, repair open circuit in POWER-to-FAN circuit from pin No. 1 and pin No. 2 of IRCM vehicle harness connector to cooling fan vehicle harness connector. Reconnect all components and recheck system operation.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 23) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) Check Fan Running Mode (Low Speed) Turn ignition off. Disconnect ECA. Reconnect IRCM. Turn ignition on, leaving engine off. If fan runs, go to step 27) (3.0L SHO), or go to next step (all others). If fan does not run, replace IRCM. Reconnect ECA and recheck system operation.

26) Jumper High Speed Electric-Drive Fan Signal (HEDF) To Ground Turn ignition off. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Ensure IRCM is connected. With KOEO, perform the following test as appropriate:

3.0L Probe - Install a jumper wire between test pins No. 40 and 52 at breakout box.
All Other Vehicles - Install a jumper wire between test pins No. 31 and 40 at breakout box.

If fan speed changes from low to high, go to next step. If fan speed does not change from low to high, replace IRCM. Remove breakout box and reconnect ECA. Recheck system operation.

27) Check ECT Sensor Turn ignition off and wait 10 seconds. With breakout box installed, connect ECA and check engine coolant level. Warm engine to normal operating temperature. Turn ignition off and wait 10 seconds. Disconnect Engine Coolant Temperature (ECT) sensor harness. Set DVOM on 200-k/ohm scale. Measure resistance of ECT sensor. If reading is 1500-2000 ohms, replace ECA. Remove breakout box and reconnect all components. Recheck system operation. If reading is NOT 1500-2000 ohms, replace ECT sensor. Remove breakout box. Reconnect all components and re-evaluate symptom.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 27) to step 30). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

30) Code 83/563 Displayed: Check HEDF Relay Resistance Code 83/563 indicates failed HEDF circuit. Turn ignition off and disconnect IRCM. Set DVOM on 200-ohm scale. Measure resistance of IRCM between pins No. 17 and 24. If reading is NOT 50-100 ohms, replace IRCM and repeat QUICK TEST. If reading is 50-100 ohms, go to next step.

31) Check HEDF Circuit Continuity Turn ignition off. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-ohm scale. Perform the following test as appropriate:

3.0L Probe - Measure resistance between test pin No. 52 at breakout box and pin No. 17 of IRCM vehicle harness connector.
All Other Vehicles - Measure resistance between test pin No. 31 and IRCM vehicle harness connector pin No. 17.

If reading is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, repair open in HEDF circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

32) Check HEDF Circuit For Shorts To Ground With ignition off and breakout box installed. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Perform the following test as appropriate:

3.0L Probe - Measure resistance between test pins No. 40 and 52 at the breakout box.
All Other Vehicles - Measure resistance between test pins No. 31 and 40 at breakout box.

If reading is greater than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in HEDF circuit. Reconnect components and repeat QUICK TEST.

33) Check HEDF Circuit For Short To Power With ignition off and breakout box installed, disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Perform the following test as appropriate:

3.0L Probe - Measure resistance between test pins No. 52 and 37 at the breakout box.
All Other Vehicles - Measure resistance between test pins No. 31 and 37 at breakout box.

If resistance is greater than 10 k/ohms, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST.

If reading is 10 k/ohms or less, repair short to power. Remove breakout box and reconnect all components. Repeat QUICK TEST. If Code 83/563 is still present, replace ECA and repeat QUICK TEST.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 33) to step 35). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

35) Low Speed Fan Always On Turn ignition off. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM and set DVOM on 200-ohm scale. Perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO - Measure resistance between test pins No. 55 at breakout box and test pin No. 14 at IRCM vehicle harness connector.
All Others - Measure resistance between test pin No. 13 at breakout box and test pin No. 14 at IRCM vehicle harness connector.

If reading is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, repair open in EDF circuit. Remove breakout box. Reconnect all components and re-evaluate symptom.

36) Check EDF Circuit For Shorts To Power With ignition off, install breakout box. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO Measure resistance between test pins No. 55 and 37, and between test pin No. 55 and battery positive terminal.
All Others - Measure resistance between test pins No. 13 and 37, and between test pin No. 13 and battery positive terminal.

If reading is more than 10 k/ohms, go to next step. If each resistance is 10 k/ohms or less, repair short to power in EDF circuit, then go to next step.

37) EDF Circuit Fault Isolation With ignition off and breakout box installed, reconnect IRCM. Turn ignition on with engine off. Perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO - Install jumper wire between test pin No. 55 and test pin No. 40 or 60 at breakout box.
All Others - Install a jumper wire between test pin No. 13 and test pin No. 40 or 60 at breakout box.

If cooling fan continues to run, replace IRCM. Remove breakout box and reconnect components. Recheck system operation. If cooling fan stops running, replace ECA. Remove breakout box and reconnect all components. Recheck system operation.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 37) to step 40). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

40) Check Fan Voltage Turn ignition off. Disconnect IRCM and cooling fan. Set DVOM on 200-k/ohm scale. Perform the following test as appropriate:

3.0L Probe - Measure resistance between pin No 6 and pins No. 8, 13 and 24 at IRCM vehicle harness connector.
All Others - Measure resistance between pin No 3 and pins No. 8, 13 and 24 at IRCM vehicle harness connector.

If all resistance readings are greater than 10 k/ohms, reconnect IRCM and cooling fan. Go to next step. If readings are not greater than 10 k/ohms, repair HEDF circuit pin No. 3 or 4 (pin No. 6 or 7 for 3.0L Probe) for short to power. Reconnect IRCM and re-evaluate symptom.

41) Check ECA For Short To Ground Turn ignition off and wait 10 seconds. Ensure IRCM and cooling fan are connected. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires; repair as necessary. Turn ignition on with engine off. If high-speed cooling fan does not run, replace ECA and re-evaluate symptom. If high-speed cooling fan runs, go to next step.

42) Check HEDF Circuit For Short To Ground Turn ignition off and wait 10 seconds. Disconnect IRCM. Install breakout box, leaving ECA disconnected. Set DVOM to 200-k/ohm scale. Perform the following test as appropriate:

3.0L Probe - Measure resistance between test pin No. 52 and test pins No. 40 and 60.
All Others - Measure resistance between test pin No. 31 and test pins No. 40 and 60.

If each resistance is greater than 10 k/ohms, replace IRCM. Remove breakout box and re-evaluate symptom. If resistance is less than 10 k/ohms, repair HEDF circuit between IRCM and ECA for short to ground. Remove breakout box and re-evaluate symptom.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 42) to step 50). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

50) Check Voltage At A/C Clutch Disconnect A/C clutch. Turn ignition on, leaving engine off. Set A/C demand switch to A/C ON position (blower motor switch ON for 3.0L Probe). Set DVOM on 20-volt scale and check voltage at A/C clutch vehicle harness connector. If voltage reading is 10.5 volts or more, service A/C compressor and/or system. If voltage is less than 10.5 volts, go to next step.

51) Check Continuity Of IRCM To A/C Clutch Circuit Turn ignition off. Disconnect IRCM and A/C clutch. Set DVOM on 200-ohm scale. Measure resistance between IRCM vehicle harness connector pin No. 23 and power circuit pin at A/C clutch harness connector. Also measure resistance between IRCM vehicle harness connector pin No. 16 and ground circuit at A/C clutch harness connector. If readings are more than 5 ohms, repair open in power or ground circuit(s) of A/C, and re-evaluate symptom. If readings are 5 ohms or less, go to next step.

52) Check For Voltage To ECA Turn ignition off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires; repair as necessary. Install breakout box, leaving ECA disconnected. Disconnect A/C clutch electrical connector. Set DVOM to 20-volt scale. Turn ignition on with engine off. Turn A/C demand switch to A/C position (blower motor switch ON for 3.0L Probe). Measure voltage between test pins No. 10 and 40. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, go to step 54).

53) Check Continuity Of ACCS Circuit To IRCM Turn ignition off and wait 10 seconds. Install breakout box. Disconnect ECA and IRCM connectors. Set DVOM on 200-ohm scale. Perform the following test as appropriate:

Vehicles With Heated Front Windshield - Disconnect heated windshield module. Measure resistance between test pin No. 10 of breakout box and pin No. 5 of heated windshield module connector, and between pin No.3 of heated windshield module connector and pin 21 of IRCM vehicle harness connector.
All Others - Measure resistance between test pin No. 10 of breakout box and IRCM harness connector pin No. 21.

If reading is more than 5 ohms, service open in ACCS circuit. Remove breakout box and reconnect all components. Re-evaluate symptom. If reading is 5 ohms or less, reconnect heated windshield module, if applicable, and go to step 55).

Fig 5: Heated Windshield Module Connector

54) Check Voltage To Cyclic Pressure Switch Turn ignition on, leaving engine off. Disconnect cyclic pressure switch. Turn A/C demand switch to A/C position (blower motor switch ON for 3.0L Probe). Set DVOM to 20-volt scale. Measure voltage between cyclic pressure switch connector and battery negative terminal. If voltage is greater than 10.5 volts, repair open in ACCS circuit. Remove breakout box, reconnect all components and re-evaluate symptom. If voltage is less than 10.5 volts, EEC system okay. Remove breakout box, reconnect all components and diagnose A/C system.

55) Check WAC Circuit For Shorts To Ground Turn ignition off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale. Measure resistance, in turn, between test pin No. 54 and the following: test pin No. 40, test pin No. 46, and battery negative terminal. If all readings are 10 k/ohms or more, go to step 58). If any reading is less than 10 k/ohms, repair short to ground in WAC circuit. Remove breakout box and reconnect all components. Re-evaluate symptom.

56) Check Continuity In WAC To IRCM Circuit Turn ignition off and wait 10 seconds. Install breakout box. Disconnect ECA and IRCM. Set DVOM on 200-ohm scale, and measure resistance between test pin No. 54 and IRCM vehicle harness connector pin No. 22. If reading is 5 ohms or less, go to next step. If reading is more than 5 ohms, repair open in WAC circuit. Remove breakout box and reconnect all components. Re-evaluate symptom.

57) Check WAC Circuit For Short To Power Turn ignition off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 54 and 37, and between test pin No. 54 and battery positive terminal. If all readings are 10 k/ohms or more, go to next step. If any reading is less than 10 k/ohms, repair shorts to power in WAC circuit. Remove breakout box, reconnect all components and go to next step.

58) Check Voltage At A/C Clutch Turn ignition off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Connect IRCM connector and disconnect A/C clutch. Place A/C demand switch to A/C ON position (blower switch ON for 3.0L Probe). Connect jumper wire between test pins No. 22 and 40. With KOEO, set DVOM on 20-volt scale. Disconnect and reconnect jumper several times while observing voltage at A/C clutch vehicle harness connector. Wait 5 seconds after each action before reading voltage.

Remove jumper wire and repeat procedure with jumper wire connected between test pins No. 54 and 40. If voltage cycles from less than one volt to greater than 10 volts in at least one of the tests, replace ECA. Remove breakout box, reconnect all components and re-evaluate symptom. If voltage does not cycle from less than one volt to greater than 10 volts in at least one of the tests, replace IRCM. Remove breakout box, reconnect all components and re-evaluate symptom.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 58) to step 80). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

80) Code 88/564: Check EDF Signal To The IRCM For Short To Ground If fan is always on with Code 88/564, go to step 82). With ignition off, disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale, and perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO - Measure resistance between test pins No. 40 and 55.
All Others - Measure resistance between test pins No. 40 and 13.

If reading is more than 10 k/ohms, go to next step. If reading is 10 k/ohms or less, repair short to ground in EDF circuit. Reconnect all components and repeat QUICK TEST.

81) Check Fan Running Mode With ignition off and breakout box installed, disconnect ECA and connect IRCM connector. Turn ignition on. If fan runs, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST. If fan does not run, replace IRCM. Remove breakout box. Reconnect all components and repeat QUICK TEST.

82) Fan Always On With Code 88/564: Check EDF Signal Circuit To IRCM Continuity Turn ignition off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair as necessary. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-ohm scale, and perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO - Measure resistance between test pin No. 55 at breakout box and pin No. 14 at IRCM harness connector.
All Others - Measure resistance between test pin No. 13 at breakout box and pin No. 14 at IRCM harness connector.

If reading is 5 ohms or less, go to next step. If reading is greater than 5 ohms, repair open in EDF circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

83) Check EDF Circuit For Short To Power Turn ignition off. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale. Perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO - Measure resistance between test pins No. 55 and 37, and between test pin No. 55 and battery positive terminal.
All Others - Measure resistance between test pins No. 13 and 37, and between test pin No. 13 and battery positive terminal.

If readings are 10 k/ohms or less, repair short to power in EDF circuit. After repairs, go to next step. If readings are greater than 10 k/ohms, go to next step.

84) Check EDF For Shorts To Ground Turn ignition off. Install breakout box, leaving ECA disconnected. Ensure IRCM is properly connected. Turn ignition on. Using jumper wire, perform the following test as appropriate:

3.0L Probe & 3.0L SPFI-MA SHO - Connect test pin No. 55 to test pin No. 40 or 60.
All Others - Connect test pin No. 13 to test pin No. 40 or 60.

If fan continues to run, replace IRCM. Remove breakout box and reconnect all components. Repeat QUICK TEST. If fan does not run, replace ECA. Remove breakout box. Reconnect all components and repeat QUICK TEST.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 84) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Code 95/542: Check Inertia Switch KOEO Code 95/542 indicates one of the following condition:

Open circuit in fuel pump or between fuel pump and FPM circuit
Poor fuel pump ground connection
FUEL PUMP circuit shorted to power
Fuel pump relay contacts always closed

Turn ignition off and wait 10 seconds. Locate and disconnect fuel pump inertia switch. Set DVOM on 200-ohm scale. Measure resistance of fuel pump inertia switch. If resistance is less than 5 ohms, reconnect inertia switch and go to next step. If resistance is more than 5 ohms, replace or reset inertia switch and rerun QUICK TEST.

91) Ensure Fuel Pump Is Off Turn ignition off. Listen for fuel pump operation. If pump is still running, go to next step. If pump is off, go to step 93).

92) Check For Closed Fuel Pump Relay With ignition off, locate and disconnect IRCM. If fuel pump shuts off when controller is disconnected, replace IRCM and rerun QUICK TEST. If pump does not shut off, repair short to power in POWER-to-PUMP (FPM) circuit. Reconnect IRCM and rerun QUICK TEST.

93) Check Continuity Of FPM Circuit With ignition off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair as necessary. Install breakout box, leaving ECA disconnected. Disconnect IRCM. Set DVOM on 200-ohm scale and measure resistance between FPM circuit at breakout box and pin No. 5 of IRCM vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST.

94) Check For Continuity Between FPM Circuit & Ground With ignition off, install breakout box and leave ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-ohm scale and measure resistance between FPM circuit at breakout box and battery negative terminal. If resistance is greater than 5 ohms, repair fuel pump circuit or replace fuel pump; rerun QUICK TEST. If resistance is less than 5 ohms, go to next step for dual-HEGO vehicles. On all other vehicles, replace ECA; remove breakout box, reconnect all components and retest system.

Due to the internal circuitry of the ECA, a short to power in left/front HEGO signal could produce Code 95/542 or 96/543.

95) Check Left/Front HEGO Sensor For Short To Power Turn ignition off and wait 10 seconds. Set DVOM to 200-k/ohm scale. Disconnect left/front HEGO sensor. Measure resistance between HEGO signal pin and KEY POWER pin at HEGO sensor connector. Is resistance is greater than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, replace HEGO sensor and rerun QUICK TEST.

Fig 1: HEGO Sensor Connector

96) Check HEGO Circuit For Short To Power Turn ignition off and wait 10 seconds. Set DVOM to 20-volt scale. Disconnect left/front HEGO. Disconnect ECA 60-pin connector and inspect for damaged or pushed-out pins, corrosion, loose wire, or other damage. Leave ECA disconnected. Turn ignition on and measure voltage between HEGO signal at HEGO vehicle harness connector and chassis ground. If voltage is less than one volt, replace ECA; reconnect HEGO sensor and rerun QUICK TEST. If voltage is greater than one volt, repair short circuit. Reconnect ECA and HEGO sensor. Rerun QUICK TEST.

Fig 2: HEGO Sensor Vehicle Harness Connector

NOTE: There is a break in the step numbering sequence at this point, skipping from step 96) to step 100). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

100) Code 96/543: Check POWER-To-PUMP Circuit Continuity Code 96/543 indicates that when fuel pump is activated, no power is supplied to pump. Turn ignition off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair as necessary. Install breakout box, leaving ECA disconnected. Disconnect IRCM. Set DVOM on 200-ohm scale. Measure resistance between FPM circuit at breakout box and pin No. 5 at IRCM vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open in POWER-to-PUMP circuit between FPM splice and IRCM. Remove breakout box and reconnect all components. Rerun QUICK TEST.

101) Check Fuel Pump Operation With ignition off, disconnect ECA 60-pin connector. Install breakout box and reconnect ECA and IRCM. Set DVOM on 20-volt scale. Connect DVOM between FPM circuit and test pin No. 40 at breakout box. Observe DVOM and turn ignition to ON position. If voltage is greater than 9.8 volts for about one second after key is turned on, replace ECA. Remove breakout box and rerun QUICK TEST. If voltage is not as specified, go to next step.

102) Code 59/524: Measure Low Fuel Pump Relay Power Circuit Continuity Code 59/524 indicates low fuel pump is not receiving correct supplied voltage through circuit. Turn ignition off. Disconnect IRCM. Set DVOM on 200-ohm scale. Measure resistance between pin No. 10 at IRCM vehicle harness connector and battery positive terminal. If resistance is less than 5 ohms, go to step 100). If resistance is not less than 5 ohms, repair low fuel pump circuit. Ensure circuit shorting plug is connected. Reconnect IRCM and repeat QUICK TEST.

103) Check Power To IRCM Turn ignition off and wait 10 seconds. Disconnect IRCM connector. Set DVOM to 20-volt scale. Measure voltage between pin No. 12 of IRCM vehicle harness connector and battery negative terminal. If voltage is greater than 10.5 volts, replace IRCM. Remove breakout box, reconnect all components and rerun QUICK TEST. If voltage is less than 10.5 volts, repair open circuit in the POWER-to-IRCM circuit. Clear codes and rerun QUICK TEST.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 103) to step 105). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

105) Continuous Memory Code 95/542: Check EEC-IV Harness Continuous Memory Code 95/542 indicates one of the following intermittent conditions has occurred:

Open circuit in or between fuel pump and FPM circuit in the ECA
Poor fuel pump ground

Start engine. Check for engine stall or stumble, and listen for fuel pump shutting off while performing the following:

Shake, wiggle and bend power-to-pump circuit between IRCM pin No. 5 and fuel pump.
Shake, wiggle and bend fuel pump ground circuit from fuel pump to ground.
Lightly tap inertia switch and fuel pump to simulate road shock.

Turn ignition off. Inspect fuel pump electrical connector and fuel pump ground for corrosion, damaged pins, or other damages. If fault is found or indicated, isolate fault and repair as necessary. Clear codes and rerun QUICK TEST. If fault is not indicated or found, go to next step.

106) Check FPM Circuit Turn ignition off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires; repair as necessary. Install breakout box, leaving ECA disconnected. Connect test light between FPM circuit and test pin No. 37. With KOEO, observe test light for indication of fault while performing wiggle test on circuit between ECA and splice in POWER-to-PUMP circuit. If fault is indicated or found, isolate fault and repair as necessary. Remove breakout box and reconnect all components. Clear codes and rerun QUICK TEST. If fault is not indicated or found, fault cannot be duplicated or identified at this time. Clear codes and rerun QUICK TEST.

NOTE: There is a break in the step numbering sequence at this point, skipping from step 106) to step 110). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

110) Code 59/524 Or 96/543: Check For Code 83/557 Or 87/556 If Continuous Memory Code 83/557 or Code 87/556 is also present, go to step 112). If Code 83/557 or 87/556 is not present, go to next step.

111) Check EEC Harness Continuous Memory Code 95/542 or 96/543, without the present of Continuous Memory Code 83/557 or 87/556, indicates one of the following intermittent conditions has occurred:

Fuel pump relay contacts open
Open in POWER-to-PUMP circuit from IRCM pin No. 5 to FPM circuit at the ECA.

Start engine. Check for engine stall or stumble, and listen for fuel pump shutting off while performing the following:

Shake, wiggle and bend POWER-to-PUMP circuit between IRCM to ECA.
Lightly tap IRCM to simulate road shock.

Turn ignition off. Inspect IRCM 24-pin connectors for corrosion, damaged pins, or other damages. If fault is found or indicated, isolate fault and repair as necessary. Clear codes and rerun QUICK TEST. If fault is not indicated or found, fault cannot be duplicated or identified at this time. Clear codes and rerun QUICK TEST.

112) Code 83/557 Or 87/556: Check EEC Harness Continuous Memory Code 83/557 or 87/556 indicates that one of the following intermittent conditions has occurred:

Open VPWR circuit in IRCM
Open coil in fuel pump relay
Open in fuel pump primary circuit

Start engine. Check for engine stall or stumble, and listen for fuel pump shutting off while performing the following:

Shake, wiggle and bend EEC harness fuel pump circuit (pin No. 22) between ECA and IRCM (pin No. 18).
Shake, wiggle and bend EEC harness fuel pump circuit (pin No. 41) between ECA and IRCM (pin No. 11).
Lightly tap IRCM to simulate road shock.

Turn ignition off. Inspect ECA 60-pin connector and IRCM 24-pin connector for corrosion, damaged pins, or other damages. If fault is indicated or found, isolate and repair fault as necessary. Clear codes and rerun QUICK TEST. If fault is not indicated or found, fault cannot be duplicated or identified at this time. Clear codes and rerun QUICK TEST.