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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 43 (Engine Controls - Tests W/Codes - 8.0L) >> Self-Diagnostic Tests >> Test TC-39A - Auto Shutdown Relay Control Circuit (DTC 42)

Test TC-39A - Auto Shutdown Relay Control Circuit (DTC 42)

WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS  section at the end of this article.
  1. Using scan tool, actuate Auto Shutdown (ASD) relay. If ASD relay is not clicking, go to step 5). If ASD relay is clicking, condition required to set trouble code is not present at this time. Go to next step.
  2. AUTO SHUTDOWN RELAY CONTROL CIRCUIT trouble code sets if an open or short is detected in ASD relay control circuit (Dark Blue/Yellow wire). Possible causes are: open or short in ASD relay coil windings, open in ASD relay fused ignition switch output circuit (Light Green/Black wire), open or short in ASD relay control circuit (Dark Blue/Yellow wire) or failed driver in PCM. Go to next step.
  3. Inspect all related wiring and connectors. Repair as necessary. Perform TEST VER-2. If no problems are found with wiring and connectors, go to next step.
  4. Start engine. Wiggle wiring harness from ASD relay to PCM. If engine misfires or stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to misfire or stall. Perform TEST VER-2. If engine does not misfire or stall, see INACTIVE DTC CONDITION  .
  5. Remove ASD relay. Scan tool should still be actuating ASD relay. Using scan tool in voltmeter mode, check voltage on ASD relay connector, fused ignition switch output circuit (Light Green/Black wire). If voltage is less than 10 volts, repair open Light Green/Black wire. Perform TEST VER-2.
  6. If voltage is more than 10 volts, using an external ohmmeter, check resistance across ASD relay terminals. See Figure . If resistance is more than 100 ohms, replace ASD relay. Perform TEST VER-2. If resistance is less than 100 ohms, go to next step.
  7. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Using scan tool in ohmmeter mode, check resistance of PCM connector terminal No. 51, ASD relay control circuit (Dark Blue/Yellow wire). If resistance is less than 5 ohms, repair short to ground in Dark Blue/Yellow wire. Perform TEST VER-2.
  8. If resistance is more than 5 ohms, using an external ohmmeter, check resistance of control circuit (Dark Blue/Yellow wire) between ASD relay connector and PCM connector terminal No. 51. If resistance is more than 5 ohms, repair open Dark Blue/Yellow wire. Perform TEST VER-2. If resistance is less than 5 ohms, replace PCM. Perform TEST VER-2.
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