DTC P1388: ASD RELAY CONTROL CIRCUIT Dodge Ram Wagon B1500

Note. For connector terminal identification, see CONNECTOR IDENTIFICATION . For circuit identification and wiring diagram, see RAM VAN & RAM WAGON wiring diagram in WIRING DIAGRAMS article.

Note. DTC P1388: ASD RELAY CONTROL CIRCUIT is monitored with ignition on and battery voltage more than 10.4 volts. DTC may be stored in Powertrain Control Module (PCM) when PCM senses an open or short condition in ASD relay circuit. Possible causes are: defective ASD relay, defective PCM, defective connectors or defective wiring.

1. Turn ignition on, with engine off. Using scan tool, actuate ASD relay. ASD relay is located in Power Distribution Center (PDC). PDC is located next to battery. Refer to label under PDC cover for relay location. If ASD relay is clicking, go to next step. If ASD relay is not clicking, go to step 5).
2. Turn ignition off. Inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. Perform TEST VER-2A. If connectors and wiring harness are okay, go to next step.
3. Start engine and allow it to idle. Wiggle wiring harness from ASD relay to PCM. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. If engine stalls while wiggling wiring harness, repair wiring harness as necessary where wiggling caused engine to stall. Perform TEST VER-2A. If engine does not stall while wiggling wiring harness, go to next step.
4. Check FREEZE FRAME data to determine conditions when DTC was set. Road test vehicle to attempt to duplicate FREEZE FRAME conditions. If conditions do not exist, conditions required to set DTC are not present at this time. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. Perform TEST VER-5A. If connectors and wiring harness are okay, test is complete.
5. Turn ignition off. Remove ASD relay. Clean and/or repair connector as necessary. Turn ignition on, with engine off. Using a voltmeter, check voltage on ASD relay connector, fused ignition switch output circuit (Light Green/Black wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open fused ignition switch output circuit. Perform TEST VER-2A.
6. Turn ignition off. Ensure ASD relay is still removed. Using an ohmmeter, check resistance between ASD relay terminals No. 85 and 86. If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, replace ASD relay. Perform TEST VER-2A.
7. Ensure ignition is off. Ensure ASD relay is still removed. PCM connectors. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. Clean and/or repair connectors as necessary. Using ohmmeter, check resistance of ASD relay control circuit (Dark Blue/Yellow wire) between ASD relay connector and PCM. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open ASD relay control circuit. Perform TEST VER-2A.
8. Ensure ignition is off. Ensure ASD relay is still removed. Ensure PCM connectors are still disconnected. Using ohmmeter, check resistance between ground and PCM connector, ASD relay control circuit (Dark Blue/Yellow wire). If resistance is less than 5 ohms, repair ASD relay control circuit for short to ground. Perform TEST VER-2A. If resistance is 5 ohms or more, go to next step.
9. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-2A.