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Home › Ford › 1996 › RV Cutaway 7.3 F › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes - 7.3L Diesel - EEC-IV › Pinpoint Tests › Pinpoint Test W: Injector Driver Module Enable › Diagnostic Aids

Diagnostic Aids

  1. 1) DTC 1662: Verify Battery Voltage At IDM Primary Circuit

    DTC 1662 indicates PCM has detected an IDM-EN circuit malfunction. Possible causes for this DTC are:
    • Open fuse.
    • Open or shorted IDM-EN circuit.
    • Faulty IDM relay.
    • Faulty Powertrain Control Module (PCM).

    Remove IDM relay from power distribution box. Turn ignition on. Measure voltage between chassis ground and White/Black wire at IDM relay wiring harness connector. If battery voltage is present, go to next step. If battery voltage is not present, repair open in White/Light Blue wire. Reconnect connectors. Clear DTCs, and repeat QUICK TEST .

  2. 2) Check For Short To Ground

    Turn ignition off. Measure resistance between chassis ground and White/Black wire at IDM relay wiring harness connector. If resistance is 10 k/ohms or less, go to next step. If resistance is more than 10 k/ohms, go to step  4).

  3. 3) Check White/Black Wire For Short To Ground

    Turn ignition off. Disconnect PCM 104-pin connector. Measure resistance between chassis ground and White/Black wire at IDM relay wiring harness connector. If resistance is 10 k/ohms or less, repair short to ground in White/Black wire. Reconnect connectors. Clear DTCs, and repeat QUICK TEST . If resistance is more than 10 k/ohms, replace PCM. Reconnect connectors. Clear DTCs, and repeat QUICK TEST .

  4. 4) Verify PCM Is Enabling IDM Relay

    Turn ignition off. Measure resistance between IDM relay cavity (White/Black wire) and battery ground. Turn ignition on, while observing DVOM. If resistance changes to less than 5 ohms, replace IDM relay. Reconnect connectors. Clear DTCs, and repeat QUICK TEST . If resistance stays 5 ohms or more, go to next step.

  5. 5) Check White/Black Wire For Open

    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 of White/Black wire between IDM relay cavity and test Pin No. 70 at breakout box. If resistance is less than 5 ohms, replace PCM. Reconnect connectors. Clear DTCs, and repeat QUICK TEST . If resistance is 5 ohms or more, locate and repair open circuit in White/Black wire between PCM and IDM relay. Reconnect connectors. Clear DTCs, and repeat QUICK TEST .

  6. 6) DTC 1663 & 1667, With Or Without P1668: Check For DTC 1662

    Ensure IDM and PCM are connected. Turn ignition on. Perform KOEO SELF-TEST  under QUICK TEST. If DTC 1662 is present, go to step  1). If DTC 1662 is not present, go to next step.

  7. 7) Check MAXI Fuse

    Ensure PCM is connected. Turn ignition on. On Econoline, measure voltage between negative battery terminal and Gray 16-gage fuse link "F", located at starter motor relay. On Pickup, measure voltage between negative battery terminal and MAXI fuse No. 8, located in power distribution box in engine compartment. On all models, if battery voltage is present on both sides of fuse link or MAXI fuse, go to next step. If battery voltage is not present on both sides of fuse link or MAXI fuse, repair short to ground in Dark Green/Light Green wire and replace fuse link or MAXI fuse. Reconnect connectors. Clear DTCs, and repeat QUICK TEST .

  8. 8) Check Yellow Wire For Open

    Turn ignition off. On Econoline, disconnect fuse link "F" from power supply. On Pickup, ensure MAXI fuse No. 8 is removed from power distribution box. On all models, remove IDM relay. On Econoline, measure resistance of Yellow wire between fuse link "F" and appropriate IDM relay cavity. On Pickup, measure resistance of Yellow wire between non-powered side of MAXI fuse No. 8 and IDM relay cavity. On all models, if resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, locate and repair open circuit in Yellow wire. Clear DTCs, and repeat QUICK TEST .

  9. 9) Check Dark Green/Light Green Wire For Open

    Disconnect IDM connector. Measure resistance of Dark Green/Light Green wire between IDM harness connector terminal No. 14 and appropriate IDM relay cavity. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Green/Light Green wire. Reconnect connectors. Clear DTCs, and repeat QUICK TEST .

  10. 10) Check IDM Relay

    Reinstall IDM relay. On Econoline, ensure fuse link "F" is disconnected. On Pickup, ensure MAXI fuse No. 8 is removed. On all models, ensure IDM is disconnected. Turn ignition on. On Econoline, measure resistance between fuse link "F" (Yellow wire) and IDM harness connector terminal No. 14 (Dark Green/Light Green wire). On Pickup, measure resistance between non-powered side of MAXI fuse No. 8 (Yellow wire) and IDM harness connector terminal No. 14 (Dark Green/Light Green wire). On all models, if resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace IDM relay. Reconnect all connectors. Clear DTCs, and repeat QUICK TEST .

  11. 11) Check IDM Ground Circuit

    Measure resistance of Black/White wire between negative battery terminal and IDM harness connector terminal No. 26. If resistance is less than 5 ohms, replace IDM. Reconnect all connectors. Clear DTCs, and repeat QUICK TEST . If resistance is 5 ohms or more, locate and repair open in Black/White wire. Reconnect all connectors. Clear DTCs, and repeat QUICK TEST .
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