Test Ff - Power Steering Pressure Switch (PSPS)

NOTE: Perform this test when Service Code 52 is displayed during QUICK TESTS or when directed here by other test procedures. Some vehicles may not have power steering, but the ECA may be equipped with PSPS software strategy. If a KOEO Code 52 is displayed, check to see that vehicle is equipped with power steering. If not, disregard Code 52.

NOTE: This test is intended to diagnose only the following:

Power Steering Pressure Switch (PSPS)
Harness circuits (PSPS and SIG RTN)
ECA

Fig 1: Power Steering Pressure Switch (PSPS) Circuit

WIRE COLOR IDENTIFICATION

Application (Pin No.)		Wire Color
Pin 46
F-Series & Bronco		Gray/Red
All Others		Black/White
Pins 24, 23, 2 or 3
3.0L Probe		Brown/Red
All Others		Yellow/Light Green

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: idle speed/throttle stop adjustment, binding throttle shaft/linkage or cruise control linkage.

1) Code 52 Displayed, Attempt to Eliminate Code Code 52 indicates that PSPS circuit is open. Turn key off and wait 10 seconds. Disconnect PSPS. Install a jumper wire between PSPS circuit and SIG RTN at vehicle harness connector. Repeat KOEO Self-Test. If Code 52 is not displayed, replace PSPS and repeat QUICK TEST. If Code 52 is still displayed, go to next step.

2) Check Continuity of PSPS Circuits Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale and measure resistance between test pin No. 46 and SIG RTN circuit at the PSPS vehicle harness connector. If both readings are less than 5 ohms, replace ECA. Remove breakout box, reconnect all components and repeat QUICK TEST. If readings are greater than 5 ohms, repair open in circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

3) Check PSPS Operation Connect tachometer and start engine. Allow engine to idle in Park or Neutral. Disconnect PSPS at switch. If RPM increases, replace PSPS. Recheck system. If RPM does not increase, go to next step.

4) Check PSPS Circuits For Shorts Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 24 (test pin No. 2 on 3.0L SHO PFI) and test pin No. 46 at the breakout box. If resistance is 10 k/ohms or less, repair short in harness. Remove breakout box, reconnect all components and recheck symptom. If reading is greater than 10 k/ohms, replace ECA. Repeat QUICK TEST.

5) KOER Self-Test Code 52 Displayed Disregard this code if vehicle does not have power steering. Code 52 indicates that PSPS did not change states due to switch being either open or closed. If you turned steering wheel 1/2 turn within 1-2 seconds AFTER engine ID code, and front wheels are centered in a no load condition, go to next step. If not, repeat QUICK TEST.

6) Checking ECA Open Circuit Identifying Capabilities Turn key off and wait 10 seconds. Disconnect PSPS. Perform KOEO Self-Test. If Code 52 is present, go to step 8). If Code 52 is not present, go to next step.

7) Check PSPS Circuits For Shorts Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box, leaving ECA disconnected, and set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 46 and 24 (test pin No. 2 on 3.0L SHO PFI) at breakout box. If reading is 10 k/ohms or less, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST. If reading is 10 k/ohms or more, replace ECA. Remove breakout box, reconnect all components and repeat QUICK TEST.

8) Check PSPS Position Comparison Turn key off and wait 10 seconds. Install breakout box, leaving ECA connected. With PSPS connected, set DVOM on 200-ohm scale. Turn key on and measure resistance between test pin No. 24 (test pin No. 2 on 3.0L SHO PFI) and test pin No. 46. Start engine. If reading remains less than 10 ohms between KOEO and KOER, go to next step. If not, go to step 11).

9) Check PSPS State With KOER: Load & No Load Install breakout box and connect ECA. Connect PSPS and set DVOM on 200-ohm scale. Start engine and allow it to idle. Ensure clutch is not depressed on 3.0L SHO PFI vehicles equipped with manual transmissions. Measure resistance between test pin No. 24 (test pin No. 2 on 3.0L SHO PFI) and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 10 ohms to infinity (indicating PSPS opening) and then returns to 10 ohms or less (when steering wheel is centered), PSPS system is okay. Remove breakout box and return to QUICK TEST. If reading did not change as indicated, go to next step.

10) Check For PSPS Always Closed Compared to Hydraulic Pressure With Engine Running At this point, there are only 2 possible causes for the original KOER Code 52. They are a PSPS switch that will not open, or low available hydraulic pressure. Turn key off and wait 10 seconds. Substitute original switch with a known good PSPS switch. Perform KOER Self-Test and turn steering wheel at least 1/2 turn after engine ID code. If Code 52 is still present, check power steering system for hydraulic pressure. If Code 52 is not present, replace original PSPS switch. Service other codes if necessary.

11) Check For PSPS Always Open Compared to Hydraulic Pressure With Engine Running At this point, there are only 2 possible causes for original KOER Code 52. They are a PSPS switch that is always open, or excessively high hydraulic pressure. Turn key off and wait 10 seconds. Substitute original PSPS with a known good PSPS. Perform KOER Self-Test and turn steering wheel at least 1/2 turn after engine ID code. If Code 52 is still present, check power steering system for excessive hydraulic pressure. If Code 52 is not present, replace original PSPS switch. Service other codes if necessary.