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DTC P1388: Auto Shutdown Relay Control Circuit: Testing

  1. Turn ignition on, engine not running. With the DRBIII®, read DTCs. Is the DTC Specific Good Trip counter displayed and equal to zero? If yes, go to next step. If no, go to INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Measure the resistance between terminals No. 85 and 86 of the ASD Relay (component side). Is the resistance between 50 and 80 ohms? If yes, go to next step. If no, replace the ASD Relay. Turn the ignition off. Remove the ASD relay from the PDC. Turn ignition on, engine not running. Measure the voltage on the Fused Ignition Switch Output circuit at the ASD Relay connector in the PDC. Is the voltage above 10.0 volts? If yes, go to next step. If no, repair the Fused Ignition Output circuit for an open. Check all related fuses and replace as necessary.
  3. Ignition on, engine not running. Using a 12-volt test light connected to ground, probe the (F15) Fused Ignition Switch Output circuit at the ASD Relay connector in the PDC. Does the test light illuminate brightly? If yes, go to the next step. If no, repair the open or short to ground in the (F15) Fused Ignition Output. Inspect the related fuse and repair as necessary.
  4. Turn the ignition off and disconnect the PCM harness connectors. Measure the resistance of the ASD Relay Control circuit from the ASD Relay cavity in the PDC to the PCM harness connector. Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the ASD Relay Control circuit for an open.
  5. Measure the resistance between ground and the ASD Relay Control circuit at the PDC. Is the resistance below 100 ohms? If yes, repair the ASD Relay Control circuit for a short to ground. If no, go to next step.
    6. NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
  6. Using the wiring diagram as a guide, inspect the wire harness and connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .
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