Circuit Test DS - Programmable Speedometer/Odometer Module
Diagnostic Aids: Perform this test when directed by QUICK TEST . This CIRCUIT TEST is intended to diagnose:
- PSOM output to PCM.
- PSOM (+) and PSOM (-) wiring harness circuits.
- PCM.
To prevent replacement of good components, be aware following non-EEC related areas and components may be cause of problem:
- Cruise Control system.
- Rear anti-lock brake system.
- Ring gear inside differential.
- Instrumentation system.
TEST PIN NO. 3 (PSOM +) WIRE COLOR IDENTIFICATION
| Application | Wire Color |
|---|---|
| All Models | Gray/Black |
TEST PIN NO. 6 (PSOM -) WIRE COLOR IDENTIFICATION
| Application | Wire Color |
|---|---|
| All Models | Pink/Orange |
- Continuous Memory Code 29/452 Code 29/452 indicates PCM detected incorrect output from VSS sometime during vehicle operation. Following are possible causes of code.
- PSOM output to PCM.
- PSOM (+) and PSOM (-) wiring harness circuits.
- PCM.
Turn ignition off. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 3 and 6 at breakout box. If reading is 21-55 k/ohms, go to step 4). If resistance is not 21-55 k/ohms, go to next step.
- Check PSOM Circuit Continuity Ensure ignition is off. Disconnect PSOM wiring harness connector. Measure resistance between test pin No. 3 at breakout box and PSOM (+) circuit at PSOM wiring harness connector. Measure resistance between test pin No. 6 at breakout box and PSOM (-) circuit at PSOM wiring harness connector. If resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST . If resistance is 5 ohms or less, go to next step.
- Check PSOM Circuit For Open Ensure ignition is off. Measure resistance between test pin No. 3 and test pins No. 6, 37 and 40 at breakout box. If resistance is 10 k/ohms or less, repair open circuit and repeat QUICK TEST . If resistance is more than 10 k/ohms, go to next step.
- Check RABS Sensor Resistance Turn ignition off. Remove RABS connector. See Fig 1. Measure resistance between connector terminals, If resistance is not 1300-1550 ohms, replace RABS and repeat QUICK TEST . If resistance is 1300-1550, go to next step.
- Check PSOM Output Voltage Turn ignition off. Connect PCM to breakout box. Connect wiring harness connector to PSOM. Set DVOM on 20-volt AC scale. Start engine, and warm to normal operating temperature. Using an assistant, measure voltage between test pins No. 3 and 6 while gradually increasing vehicle speed to 50 MPH. If maximum voltage is less than 4 volts, fault is in instrument cluster. If maximum voltage received is more than 4 volts, replace PCM.