Diagnostic Aids

Perform this test when instructed during QUICK TEST, or when directed by other test procedures. Some vehicles may not have power steering, but ECA may be equipped with PSPS software strategy. If a KOEO Code 52/519 is displayed, check if vehicle is equipped with power steering. If vehicle is not equipped with power steering, disregard Code 52/519. 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

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 52/519 Displayed, Attempt To Eliminate Code  Code 52/519 indicates PSPS circuit is open. Turn ignition off and wait 10 seconds. Disconnect PSPS. Install jumper wire between PSPS circuit and SIG RTN at vehicle harness connector. Repeat KOEO SELF-TEST. If Code 52/519 is not displayed, replace PSPS and repeat QUICK TEST. If Code 52/519 is still displayed, go to next step.

2) Check Continuity Of PSPS Circuits  Turn ignition off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect 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 PSPS vehicle harness connector. Also measure resistance between test pin No. 2, 24 or 28 and PSPS circuit at 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 and recheck system. If RPM does not increase, go to next step.

4) Check PSPS Circuits For Shorts  Turn ignition off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect 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. 28 on 3.8L AXODE) and test pin No. 46 at 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 52/521 Displayed  Disregard this code if vehicle does not have power steering. Code 52/521 indicates PSPS did not change states due to open or closed switch. If steering wheel was turned 1/2 turn within 1-2 seconds AFTER engine ID code, and front wheels were centered in a no-load condition, go to next step. If steering wheel was not turned, repeat QUICK TEST.

6) Checking ECA Open Circuit Identifying Capabilities  Turn ignition off and wait 10 seconds. Disconnect PSPS. Perform KOEO SELF-TEST. If Code 52/519 is present, go to step 8). If Code 52/519 is not present, go to next step.

7) Check PSPS Circuits For Shorts  Turn ignition 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. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 46 and 24 (test pin No. 28 on 3.8L AXODE) 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 ignition off and wait 10 seconds. Install breakout box, leaving ECA connected. With PSPS connected, set DVOM on 200-ohm scale. Turn ignition on and measure resistance between test pin No. 24 (test pin No. 28 on 3.8L AXODE) and test pin No. 46. Start engine. If reading remains less than 10 ohms between Key On Engine Off (KOEO) and Key On Engine Running (KOER), go to next step. If reading is not as described, 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 to idle. Measure resistance between test pin No. 24 (test pin No. 28 on 3.8L AXODE) 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 does 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 original KOER Code 52/521: a PSPS switch that will not open, or low available hydraulic pressure. Turn ignition 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 52/521 is still present, check power steering system for hydraulic pressure. If Code 52/521 is not present, replace original PSPS switch. Service other codes as 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 52/521: a PSPS switch that is always open, or excessively high hydraulic pressure. Turn ignition 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 52/521 is still present, check power steering system for excessive hydraulic pressure. If Code 52/521 is not present, replace original PSPS switch. Service other codes as necessary.