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Home >> Ford >> 1997 >> F-Super Duty 7.3 F, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Tests W/Codes - 7.3L Diesel >> Circuit Tests >> Circuit Test J - Programmable Speedometer/Odometer Module (PSOM) >> Diagnostic Aids
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Diagnostic Aids

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

To prevent replacement of good components, be aware following non-EEC related areas and components may be cause of problem:

Fig 1: Programmable Speedometer/Odometer Module (PSOM) Circuit Logic
G95J35278
Fig 2: Identifying Programmable Speedometer/Odometer Module (PSOM) Circuit & Connector Terminals
G95A35279

  1. 1) DTC P0500

    DTC P0500 indicates PCM detected incorrect output from Vehicle Speed Sensor (VSS) sometime during vehicle operation. Possible causes for this DTC are:
    • PSOM output to PCM.
    • PSOM (+) and PSOM (-) wiring harness circuits.
    • Faulty PCM.

    Turn ignition off. Disconnect PCM 104-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pins No. 33 and 58 at breakout box. If resistance is 21,000-55,000 ohms, go to step 4). If resistance is not 21,000-55,000 ohms, go to next step.

  2. 2) Check PSOM Circuit Continuity

    Ensure ignition is off. Disconnect PSOM wiring harness connector. PSOM is located behind left side of instrument panel. Measure resistance between test pin No. 58 at breakout box and PSOM (+) circuit (Gray/Black wire) at PSOM wiring harness connector. Also, measure resistance between test pin No. 33 at breakout box and PSOM (-) circuit (Pink/Orange wire) at PSOM wiring harness connector. If any reading is 5 ohms or more, locate and repair open circuit. Clear DTCs and repeat QUICK TEST . If both readings are less than 5 ohms or less, go to next step.

  3. 3) Check For Short Circuit

    Ensure ignition is off. Measure resistance between test pin No. 58 and test pins No. 33, 51 and 71 at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Clear DTCs and repeat QUICK TEST . If all readings are more than 10,000 ohms, go to next step.

  4. 4) Check Rear Anti-Lock Brake System (RABS) Sensor

    Turn ignition off. Disconnect RABS sensor connector. Sensor is located on rear differential assembly. Measure resistance between sensor terminals. If resistance is not 1300-1550 ohms, replace RABS sensor. Clear DTCs and repeat QUICK TEST . If resistance is 1300-1550 ohms, go to next step.

  5. 5) Check PSOM Output Voltage

    Turn ignition off. Connect PCM to breakout box. Connect wiring harness connector to PSOM. Set New Generation Star (NGS) scan tool for frequency measurement with a 4-volt DC scale. Connect NGS scan tool probes between test pins No. 33 and 58 at breakout box. Road test vehicle at 40 MPH or 60 MPH. Frequency should by 88-92 Hz at 40 MPH or 128-132 at 60 MPH. If frequency is as specified, replace PCM. Clear DTCs and repeat QUICK TEST . If frequency is not as specified, no fault is indicated at this time. Check for faulty instrument cluster, cruise control system or RABS.
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