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DTC P1388: Auto Shutdown Relay Control Circuit: Testing

  1. Turn ignition on. Using scan tool, read DTCs. If GOOD TRIP counter is displayed for DTC P1388 and displayed count is "0", go to next step. If GOOD TRIP counter for DTC P1388 is not displayed or displayed count is not "0", go to step  7 .
  2. Turn ignition off. Remove ASD relay. ASD relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. See Figure . Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Measure resistance of Dark Blue/Yellow wire between terminal A11 at ASD relay socket in PDC and terminal C3 at PCM C3 harness connector. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Yellow wire.
  3. Turn ignition on. Measure voltage between ground and terminal A13 (Dark Blue wire) at ASD relay socket in PDC. See Figure . If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check for repair open in Dark Blue wire between ASD relay and fuse block. Also check fuse No. 12 (10-amp) in fuse block. Fuse block is located behind glove box. Repair wiring or replace fuse as necessary.
  4. Turn ignition off. Ensure PCM is disconnected. Measure resistance between ground and terminal C3 (Dark Blue/Yellow wire) at PCM C3 harness connector. See Figure . If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Yellow wire between ASD relay and PCM.
  5. Measure resistance between terminals No. 85 and 86 at ASD relay. See Figure . If resistance is not 50-80 ohms, replace ASD relay. If resistance is 50-80 ohms, go to next step.
  6. At this time, PCM is assumed to be defective. Replace PCM.
  7. Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, reconnect all connectors. Start engine. Wiggle wiring harness from ASD relay to PCM while monitoring scan tool display. PCM is located on firewall in right rear corner of engine compartment. If GOOD TRIP counter display count changes to "0", repair connector or wiring harness where wiggling caused display to change. If GOOD TRIP counter display count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.
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