Test D3 - Air System

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: thermactor air system drive belt, air pump or valve.

Fig 1: Air Management Circuits

1. Service Codes 44 (94), 45 & 46: Verify Vacuum Line Routing. Code 44 (94) indicates thermactor system is inoperative. Code 45 indicates thermactor air not flowing upstream when signaled to do so by ECA. Code 46 indicates thermactor air not by-passed when directed. Possible causes for these faults are: vacuum hoses leaking, blocked or kinked, diverter valve or thermactor pump inoperative or AM solenoid defective or blocked. Check for correct vacuum hose routing to AM1/AM2 solenoids and by-pass diverter valve. Use vehicle emissions label as a guide. Check for kinked or blocked vacuum hoses. Check for kinked or blocked air hoses. Check for disconnected vacuum hoses. If problems are detected, correct hose routing, repair faults and repeat QUICK TEST. If vacuum routing is okay, and Code 44 (94) is displayed, go to step 4). If Code 46 is displayed, go to step 3). If Code 45 is displayed, go to next step.
2. Eliminating Displayed Code 45 (AM2). This step checks AM2 solenoid only. Disconnect and plug vacuum hose at diverter valve. Turn key off and wait 10 seconds. Repeat KOER SELF-TEST and record codes. If Code 45 is displayed, EEC system is okay. Check diverter valve and/or check valve for problem. If Code 45 is not displayed, go to step 4).
3. Eliminating Displayed Code 46 (AM1). This step checks AM1 solenoid only. Disconnect and plug vacuum hose at by-pass valve. Turn key off and wait 10 seconds. Repeat KOER SELF-TEST and record codes. If Code 46 is displayed, EEC system is okay. Check by-pass valve for problem. If Code 46 is not displayed, go to next step.
4. Output Check. Enter OUTPUT STATE CHECK, see OUTPUT STATE CHECK, under DIAGNOSTIC AIDS. Use only DVOM, not diagnostic tester, for this step. Turn key off and wait 10 seconds. With DVOM on 20-volt scale, connect DVOM negative test lead to STO circuit at SELF-TEST connector and positive test lead to battery positive terminal. Using jumper wire, connect STI to SIG RTN at SELF-TEST connector. Perform KOEO SELF-TEST until end of CONTINUOUS SELF-TEST codes (DVOM reads zero volts). Depress and release throttle. DVOM should change to a high voltage reading. If reading changed, remain in OUTPUT STATE CHECK and go to next step. If reading did not change, depress throttle to WOT and release. If STO voltage does not go high, go to TEST D16 - OUTPUT STATE  , step 1). Leave test equipment hooked up.
5. Checking AM1/AM2 Solenoid Operation. Set DVOM on 20-volt scale. Connect DVOM positive test lead to VPWR circuit and negative test lead to AM1 circuit at AM1 solenoid harness connector. See Fig 1 . While observing DVOM, depress and release throttle several times to cycle output on and off. Repeat for AM2 solenoid. Connect positive test lead to VPWR circuit and negative test lead to AM2 circuit at AM2 solenoid harness connector. Cycle AM2 solenoid on and off. If either solenoid does not cycle on and off, remove jumper and go to step 9). If both solenoids cycle on and off, go to next step.
6. Checking AM1/AM2 Solenoids For Vacuum Cycling. Connect vacuum pump to AM1 solenoid vacuum supply port. Connect vacuum gauge to output port. Maintain vacuum at source while depressing and releasing throttle to cycle output on and off. Observe vacuum gauge. Repeat for AM2 solenoid. If either output does not cycle on and off, replace solenoid assembly and repeat QUICK TEST. If both outputs cycle on and off, go to next step.
7. Checking Manifold Vacuum Lines. With vacuum hoses disconnected at AM1/AM2 solenoid assembly, start engine and check for vacuum. If vacuum is present, EEC system is okay. Check thermactor valve and air pump for problems. If no vacuum is present, repair blockage as required and repeat QUICK TEST.
8. Service Codes 81 and 82: Checking Voltage to VPWR Circuit. Code 81 and 82 indicates voltage output for thermactor air solenoid did not change when activated. Possible causes are: shorted or open circuits, solenoid resistance out of range or faulty ECA. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between AM1 solenoid VPWR circuit and battery ground. Repeat test for AM2 solenoid. If either voltage reading is less than 10.5 volts, repair harness circuit open and repeat QUICK TEST. If both readings are greater than 10.5 volts, go to next step.
9. Measuring Solenoid Resistance. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect AM1 and AM2 solenoid connectors. Measure resistance of both solenoids. If either reading is less than 50 ohms or more 100 ohms, replace solenoid assembly and repeat QUICK TEST. If both readings are between 50 and 100 ohms, connect TAB and TAD solenoids. Go to next step.
10. Checking Circuit Continuity. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires and repair as necessary. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin No. 51 and AM1 circuit at harness connector. See Fig 1 . Measure resistance between test pin No. 11 and AM2 circuit at harness connector. If either reading is 5 ohms or more, repair harness open circuit and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.
11. Checking For Shorts to Ground. Turn key off and wait 10 seconds. Set DVOM on 200K-scale. Leave breakout box installed and ECA disconnected. Disconnect AM1/AM2 solenoids. Measure resistance between test pin No. 51 and test pins No. 40, 46 and 60, and between test pin No. 11 and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10K ohms, repair short to power. Remove breakout box, connect harness to ECA and repeat QUICK TEST. If all readings are 10K ohms or more, go to next step.
12. Checking For Shorts to Power Circuit. Turn key off and wait 10 seconds. Set DVOM on 200K-ohm scale. Leave breakout box installed with ECA and solenoids disconnected. Measure resistance between test pin No. 51 and test pins No. 37 and 57 and between test pin No. 11 and test pins No. 37 and 57. If any reading is less than 10K ohms, repair short to power. Remove breakout box, connect harness to ECA and repeat QUICK TEST. If code is repeated, replace ECA. If all readings are 10K ohms or more, replace ECA and repeat QUICK TEST.