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Home >> Ford >> 2003 >> Excursion 6.0 P, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 7.3L (995, 996 F650/750, 99F E Series & 99F F450/550) DIESEL) >> System Tests >> Test H: Auxiliary Powertrain Control System >> Testing

Test H: Auxiliary Powertrain Control System: Testing

WARNING: This page is about a different variant/trim than selected.

  1. 1) Verify Operation Procedure

    Ensure vehicle has proper calibration. Refer to auxiliary powertrain control manual provided with system to verify correct operating procedures and entry conditions. If entry conditions are met and proper calibration is installed, go to next step. If entry conditions are not met and proper calibration is not installed, correct operating procedure or correct calibration level as necessary. Clear error codes and DTCs and retest. If system still does not operate, go to next step.
    2. NOTE: When performing KOER SWITCH TEST, wait 5 seconds after pressing "Trigger" to start test before running through driver operated controls. Test may take up to 5 minutes to complete.

  2. 2) Check For DTCs
    Ensure auxiliary powertrain control system is off. Using scan tool, perform KOEO ON-DEMAND SELF-TEST , KOER ON-DEMAND SELF-TEST  and KOER SWITCH SELF-TEST  under QUICK TEST. Retrieve DTCs. If any DTCs are present, service DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, go to next step.

  3. 3) Check For KEY ON Power

    Turn ignition off. Disconnect APCM connector. Connector is located behind left side of instrument panel, near steering column. Turn ignition on. Using DVOM, check for battery voltage between chassis ground and specified APCM PWR circuit at APCM harness connector. See APCM CIRCUIT WIRE COLOR IDENTIFICATION  table. See Figure-Figure . If battery voltage is present, go to next step. If battery voltage is not present, locate and repair open in Red/Light Green wire between ignition switch and APCM Econoline), or remove and inspect APCM PWR circuit fuse located in central junction box (F250-750). Central junction box is located behind lower left side of instrument panel. If fuse is blown, replace fuse and check for short to ground in Red/Yellow wire. If fuse is okay, repair open in Red/Yellow wire between central junction box and APCM. Clear codes and retest.

  4. 4) Check GND Circuit

    Turn ignition off. Using DVOM, measure resistance between chassis ground and specified GND terminal at APCM harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between APCM and ground. Clear codes and retest.

  5. 5) Check For Open In BUS (-) Circuit

    Using DVOM, measure resistance of BUS (-) circuit between specified terminal at APCM harness connector and terminal No. 10 at Data Link Connector (DLC). See APCM CIRCUIT WIRE COLOR IDENTIFICATION  table. See Figure-Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in BUS (-) circuit. Clear codes and retest.

  6. 6) Check For Open In BUS (+) Circuit

    Using DVOM, measure resistance of BUS (+) circuit between specified terminal at APCM harness connector and terminal No. 2 at DLC. If resistance is less than 5 ohms, replace APCM. Clear codes and retest. If resistance is 5 ohms or more, locate and repair open in BUS (+) circuit. Clear codes and retest.

  7. 7) APCM Inoperative With Hazard Flashers (Except Cutaway)

    Turn ignition off. Apply service brake pedal. If hi-mount brakelight illuminates, go to TEST FD, step  1). If hi-mount brakelight does not illuminate, go to next step.

  8. 8) Check Hi-Mount Brakelight

    Remove and inspect hi-mount brakelight bulb. Bench test bulb by applying battery voltage to one side and ground to the other. Replace bulb as necessary and retest system operation. Clear codes and retest. If bulb is okay, go to next step.

  9. 9) Check GND Circuit

    Using DVOM, measure resistance of Black wire between chassis ground and hi-mount brakelight bulb socket. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, locate and repair open in ground circuit. Clear codes and retest.

  10. 10) Check For PWR Circuit To Brakelight Bulb

    Turn ignition off. Apply service brake pedal. Using non-powered test light, probe between chassis ground and Light Green wire at hi-mount brakelight bulb socket. If battery voltage is present, check for loose connection in bulb socket. Repair as necessary. Clear codes and retest. If battery voltage is not present, repair open in Light Green wire. Clear codes and retest.
    11. NOTE: Cutaway models are equipped with a brake resistor to simulate hi-mount brakelight bulb. Brake resistor is also referred to as brakelight switch jumper.

  11. 11) APCM Inoperative With Hazard Flashers (Cutaway)
    Disconnect brake resistor, located on left "B" pillar. Using DVOM, measure resistance of Black wire between resistor connector and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire. Clear codes and retest.

  12. 12) Check Power Circuit To Brake Resistor

    Apply service brake pedal. Using non-powered test light, probe between Light Green wire at brake resistor connector and chassis ground. If test light illuminates, go to next step. If test light does not illuminate, repair open in Light Green wire. Clear codes and retest.

  13. 13) Check Brake Resistor

    Using a DVOM, measure resistance across brake resistor. If resistance is 130-150 ohms, reconnect resistor and go to TEST FD, step  1). If resistance is not 130-150 ohms, replace resistor. Clear codes and retest.
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