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DTC P1388: Auto Shutdown Relay Control Circuit: Testing

  1. Turn ignition on with engine off. Using scan tool, actuate ASD relay. Listen for clicking sound at ASD relay. ASD relay is located in Integrated Power Module (IPM). IPM is located on left side of engine compartment, next to battery. If clicking sound is heard at ASD relay, go to next step. If no clicking sound is heard at ASD relay, go to step  4.
    NOTE: The Intelligent Power Module (IPM) may also be referred to as Integrated Power Module (IPM) or Power Distribution Center (PDC).
  2. Turn ignition on. Ensure ASD relay is still activated. Wiggle wiring harness and connectors between ASD relay and PCM. PCM is located between on left side of engine compartment, in front of battery. If relay clicking sound continues, go to next step. If relay stops clicking while wiggling wiring harness and connectors, repair wiring or connectors as necessary that caused relay to stop clicking.
  3. At this time, conditions for DTC to set do not exist or fault is an intermittent problem. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, monitor parameters related to DTC while wiggling connectors and wiring harness. If value changes while wiggling connectors and wiring harness, repair connectors and wiring harness where wiggling caused value to change. If value does not change, review Freeze Frame data using scan tool. Attempt to duplicate condition that caused DTC to set. Check for any related technical service bulletins that may apply. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. See WIRING DIAGRAMS article. If no problems are indicated, test is complete.
  4. Turn ignition off. Remove and inspect fuse No. 16 (25-amp) in IPM. If fuse is blown, check for short to ground in ASD relay output circuit. See WIRING DIAGRAMS article. Repair wiring as necessary and install new fuse. If fuse is okay, reinstall fuse. Remove ASD relay from IPM. Using a test light connected to ground, probe terminals No. 86 and 87 at ASD relay socket in IPM. If test light illuminates at both terminals, go to next step. If test light does not illuminate at one or both terminals, replace IPM.
  5. Using a test light connected to positive battery voltage, probe terminal No. 85 at ASD relay socket in IPM. Turn ignition on. Using scan tool, actuate ASD relay. If test light does not flash on and off, go to next step. If test light flashes on and off, replace ASD relay.
  6. Turn ignition off. Disconnect IPM C3 connector. Turn ignition on. Using scan tool, actuate ASD relay. Using a test light connected to positive battery voltage, probe terminal No. 16 (Brown/White wire) at IPM C3 harness connector. If test light does not flash on and off, go to next step. If test light flashes on and off, replace IPM.
  7. Turn ignition off. Disconnect PCM connectors. PCM is located on left side of engine compartment, in front of battery. Measure resistance of Brown/White wire between terminals No. 16 at IPM C3 harness connector and No. 67 at PCM C2 harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Brown/White wire.
  8. Measure resistance between ground and terminal No. 16 (Brown/White wire) at IPM C3 harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Brown/White wire between IPM and PCM.
  9. At this time, PCM is assumed to be defective. Replace PCM. Program the new PCM. See PROGRAMMING .
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