Possible Causes
WARNING: This page is about a different car, the 2004 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
A no communication condition could be caused by damaged wiring, terminals or connectors, damaged scan tool or RCM internal fault.
- Check RCM harness connector & pin No. 5 for damage
Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Access RCM and disconnect harness connector C2041. See RESTRAINTS CONTROL MODULE (RCM) under REMOVAL & INSTALLATION. Inspect RCM harness connector, terminal No. 5 (Light Blue/White wire), component side and harness side, for damage. See Figure & Figure . If module pin and module harness connector terminal No. 5 are okay, go to next step. If module pin and module harness connector terminal No. 5 are damaged, repair/replace as necessary. Reconnect air bag system. Retest communication with RCM. Activate air bag system. See ACTIVATING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. - Check DLC for damage
Inspect Data Link Connector (DLC) and DLC connector terminal No. 7 (Light Blue/White wire) for damage. See Fig 1 . If DLC connector and DLC connector terminal No. 7 is okay, go to next step. If DLC connector and DLC connector terminal No. 7 is damaged, repair/replace as necessary. Retest communication with RCM. Reconnect air bag system. Activate air bag system. - Check ignition circuit for open
Turn ignition switch to ON position. Measure voltage between ground and RCM harness connector C2041, terminal No. 2 (Orange/Yellow wire, circuit No. 1654). Measure voltage between ground and RCM harness connector C2041, terminal No. 13 (Orange/Yellow wire, circuit No. 1654). If voltage is more than 10 volts, go to next step. If voltage is less than 10 volts, repair open in appropriate Orange/Yellow wire. See WIRING DIAGRAMS . Retest communication with RCM. Reconnect air bag system. Activate air bag system. - Check ground circuit for open
Turn ignition switch to OFF position. Measure resistance between ground and RCM harness connector C2041, terminal No. 21 (Black/White wire, circuit No. 570). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Black/White wire. Retest communication with RCM. Reconnect air bag system. Activate air bag system. - Check Light Blue/White wire for open
Measure resistance between RCM harness connector C2041, terminal No. 5 and DLC connector terminal No. 7 (Light Blue/White wire). See Figure & Fig 1 . If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Light Blue/White wire. Retest communication with RCM. Reconnect air bag system. Activate air bag system. - Confirm RCM fault
Reconnect RCM harness connector. Turn ignition switch to ON position. Perform on-demand self-test. If scan tool communicates with RCM, fault is corrected. Activate air bag system. If scan tool does not communicate with RCM, replace RCM. Retest communication with RCM. Reconnect air bag system. Activate air bag system.