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DTC P1388: Auto Shutdown Relay Control Circuit: Testing

  1. Turn ignition on, with engine off. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and displayed count is "0", go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed or displayed count is not "0", go to step  7 .
  2. Turn ignition off. Remove ASD relay from 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. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Yellow wire between terminals No. 86 at ASD socket in PDC and terminal No. 3 at PCM C3 connector. See 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, with engine off. Using a voltmeter, measure voltage between ground and terminal No. 85 (Orange/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 Orange/Dark Blue wire between ASD relay and PDC. Also check fuse No. 12 (10-amp) in junction block. Junction block is located under left side of instrument panel. See Figure . Repair wiring or replace fuse as necessary.
  4. Measure resistance between ground and Dark Blue/Yellow wire at MAP sensor connector. 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 Fig 1 . If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, replace ASD relay.
  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, start engine and allow it to idle. With engine running, wiggle wiring harness from ignition coil rail to PCM. PCM is located on firewall in right rear corner of engine compartment. Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and displayed count changes to "0", repair wiring where wiggling caused display to change. If DTC SPECIFIC GOOD TRIP counter is not displayed or displayed count does not change to "0", no problem is indicated at this time. Check for any related technical service bulletins that may apply.
Fig 1: Identifying Auto Shutdown Relay & Radiator Fan Relay Terminals
G99J08326Courtesy of DAIMLERCHRYSLER CORPORATION
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