Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Explorer and 1995 Ford Aerostar. However, it is still accessible from the selected car via links, so may be relevant.

Perform this test only when directed by QUICK TEST. This test is intended to diagnose:

Clutch Pedal Position (CPP) switch.
Park/Neutral Position (PNP) switch.
Powertrain Control Module (PCM).
Wiring harness circuits (CPP, PNP and SIG RTN).

Fig 1: PNP Switch Circuit Schematic (Aerostar & Explorer With A/T)

Fig 2: CPP Switch Circuit Schematic (4.0L M/T)

Fig 3: CPP Switch Circuit Schematic (All Other Models With M/T)

TEST PIN NO. 30 (CPP/PNP) WIRE COLOR IDENTIFICATION

Application	Wire Color
All Models	Light Blue/Yellow

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

Application	Wire Color
All Models	Gray/Red

1) Code 522, 525 Or 528 Code 522, 525 or 528 is a result of voltage being high at No. 30 (CPP/PNP input) while cranking engine or during KOEO SELF-TEST. Possible causes for these faults are:

CPP or PNP circuit open.
Faulty Powertrain Control Module (PCM).
Starter relay disconnected during self-test.

On all A/T models, go to step 8). On M/T models, go to next step.

2) Check CPP/PNP Input Turn ignition off. Turn A/C off (if equipped). Disconnect 60-pin PCM connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 30 and 46 with transmission in Neutral and clutch pedal up. Also measure resistance between test pins No. 30 and 46 with transmission in gear and clutch pedal down. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, go to step 5).

3) Check CPP/PNP Switch Integrity Leave ignition off and PCM disconnected. Measure resistance between test pins No. 30 and 46 with transmission in any gear and clutch pedal up. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST. If resistance is 5 ohms or more, go to next step.

4) Check For CPP Short To Ground Leave ignition off and PCM disconnected. Disconnect CPP switch. Measure resistance between test pins No. 30 and 46. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair short circuit. Reconnect all components, and repeat QUICK TEST.

5) Check CPP/PNP Switch Leave ignition off and PCM disconnected. Locate PNP switch (on transmission) and CPP switch (at clutch pedal linkage). Disconnect wiring harness at both switches. Measure resistance across PNP switch terminals with transmission in Neutral. Also, measure resistance across CPP switch with clutch pedal down. If each resistance is 5 ohms or less, go to next step. If any resistance is more than 5 ohms, replace appropriate switch and repeat QUICK TEST.

6) Check CPP/PNP Wiring Harness Leave ignition off and PCM disconnected. Measure resistance between test pin No. 30 and the following terminals:

PNP switch wiring harness connector CPP and/or PNP terminal.
CPP switch wiring harness connector CPP and/or PNP terminal.

Measure resistance between test pin No. 46 and the following terminals:

PNP switch wiring harness connector SIG RTN terminal.
CPP switch wiring harness connector SIG RTN terminal.

If any resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If each resistance is less than 5 ohms, replace PCM and repeat QUICK TEST.

7) Check CPP Switch Turn ignition and A/C off. Disconnect 60-pin PCM connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Push clutch pedal down. Measure resistance between test pins No. 30 and 46 at breakout box. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit. Reconnect all components, and repeat QUICK TEST.

8) Check PNP Input Turn ignition and A/C off. Disconnect 60-pin PCM connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Ensure transmission is in Neutral or Park. Turn ignition on. Measure voltage between chassis ground and test pin No. 30 at breakout box. If voltage is less than one volt, replace PCM and repeat QUICK TEST. If voltage is one volt or more, go to next step.

9) Check PNP Switch Resistance Turn ignition off. Disconnect PCM from breakout box. Disconnect PNP wiring harness connector. Measure resistance across switch terminals. If resistance is less than 5 ohms, repair open PNP circuit and repeat QUICK TEST. If resistance is 5 ohms or more, replace PNP switch and repeat QUICK TEST.