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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 85 (Generator & Regulator) >> Self-Diagnostic Tests >> Test TC-2A - Generator Field Not Switching Properly

Test TC-2A - Generator Field Not Switching Properly

WARNING: This page is about a different car, the 1995 Dodge Ram Wagon, 1995 Dodge Ram Van, 1995 Dodge Pickup, and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Perform TEST TC-1A before proceeding. Perform TEST CH-VER after repairs are made.
  1. Using DRB, actuate ASD fuel system. Backprobe ASD relay output circuit (Dark Blue or Dark Green/Orange wire) at back of generator. If voltage is 10 volts or less, repair open ASD relay output circuit. If voltage is greater than 10 volts, backprobe field driver circuit (Dark Green or Dark Green/White wire) at back of generator. If voltage is greater than 10 volts, go to step 5). If voltage is 10 volts or less, go to next step.
  2. Using DRB, stop ASD fuel system actuation test. Turn ignition off. Disconnect PCM connector. Clean and repair connector as necessary. Disconnect generator harness quick disconnect (if equipped), or disconnect positive battery cable and connect DRB power clip to positive battery terminal.
  3. Disconnect harness from back of generator. Clean and repair connector as necessary. Using external ohmmeter, check resistance between generator field terminals. See Figure. If resistance is 5 ohms (10 ohms on 5.2L CNG) or more, replace generator. If resistance is less than 5 ohms (10 ohms on CNG), go to next step.
  4. Put DRB in ohmmeter mode. Probe generator harness connector field driver circuit (Dark Green or Dark Green/White wire). If resistance is less than 5 ohms, repair field driver circuit for short to ground. If resistance is 5 ohms or more, replace PCM module.
  5. Using DRB, stop ASD fuel system actuation test. Turn ignition off. Disconnect PCM connector. Clean and repair connector as necessary. Disconnect generator harness quick disconnect (if equipped), or disconnect positive battery cable. Disconnect harness from back of generator. Clean and repair connector as necessary.
  6. Using external ohmmeter, check resistance between harness connector field driver terminal (Dark Green or Dark Green/White wire) and PCM terminal No. 20. See Fig 1. If resistance is 5 ohms or more, repair open field driver circuit (Dark Green wire). If resistance is less than 5 ohms, replace PCM.
Fig 1: PCM Connector Terminal Identification
G94J65317Courtesy of CHRYSLER CORP.