DTC P1388: Automatic Shutdown Relay Control Circuit: Testing
- Turn ignition on. Using scan tool, actuate ASD relay. Listen for clicking sound at ASD relay. ASD relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to air cleaner. See Figure. If ASD relay is clicking, go to next step. If ASD relay is not clicking, go to step 4.
- Wiggle wiring harness between ASD relay and PCM while relay is being actuated. If ASD relay does not stop clicking while wiggling wiring harness, go to next step. If ASD relay stops clicking while wiggling wiring harness, repair wiring where wiggling caused clicking to stop.
- Conditions that set DTC are not present at this time. Perform the following to help identify intermittent condition:
- With engine running at normal operating temperature, wiggle related wiring harness while monitoring related parameters on scan tool. If voltage changes or DTC sets while wiggling wiring harness, repair connectors or wiring harness where wiggling caused voltage to change or DTC to set.
- Review freeze frame information on scan tool. Duplicate conditions present when DTC was set.
- Refer to any technical service bulletins that may apply.
- Visually inspect related wiring harness. Check for chafed, pierced, pinched or partially broken wires.
- Visually inspect related wiring harness connectors. Check for broken, bent, pushed out or corroded terminals.
If a problem is found, repair as necessary. If no problems are found, test is complete.
- Turn ignition off. Remove ASD relay from PDC. See Figure. Turn ignition on. Measure voltage between ground and fused battery voltage circuit (Red/Tan wire) at ASD relay harness connector terminal No. 81. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open or short in fused battery voltage circuit.
- Measure resistance of ASD relay coil as shown in illustration. See Fig 1. If resistance is 60-80 ohms, go to next step. If resistance is not 60-80 ohms, replace ASD relay.
- Turn ignition off. Disconnect PCM harness connectors. PCM is located in engine compartment, to left of air cleaner. Measure resistance of ASD relay control circuit (Dark Blue/Violet wire) between terminal No. 80 at ASD relay harness connector and terminal No. 67 at PCM C2 harness 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/Violet wire.
- Measure resistance between ground and ASD relay control circuit (Dark Blue/Violet wire) at terminal No. 80 at ASD relay 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 Dark Blue/Violet wire.
- If no other possible causes are remaining, replace PCM.