Possible Causes
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
A open or short to ground in AIR BAG warning light circuit could be caused by damaged wiring, terminals or connectors, faulty RCM, or instrument cluster internal malfunction.
- Check for hard or intermittent DTC
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). See USING SCAN TOOL under DIAGNOSTICS. Turn ignition switch to ON position. Retrieve and record any continuous Diagnostic Trouble Codes (DTCs). See RETRIEVING FAULT CODES under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST under DIAGNOSTICS. If DTC B1869 was retrieved during on-demand self-test and AIR BAG warning light does not illuminate, go to next step. If DTC B1869 was retrieved during on-demand self-test and AIR BAG warning light does illuminate, go to step 5 . If DTC B1869 was not retrieved, fault is intermittent. Go to step 9 . - Check AIR BAG warning light for short to ground
Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Access instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Measure resistance between ground and instrument cluster harness connector C220A, terminal No. 1 (Black/Yellow wire, circuit No. 608) by back-probing connector. See Figure . If resistance is more than 10 k/ohms, go to step 8 . If resistance is less than 10 k/ohms, go to next step. - Check circuit for short to ground
Disconnect instrument cluster harness connector C220A. Measure resistance between ground and instrument cluster harness connector C220A, terminal No. 1 (Black/Yellow wire). If resistance is more than 10 k/ohms, replace instrument cluster. Go to step 10 . If resistance is less than 10 k/ohms, go to next step. - Check RCM for short to ground
Access RCM and disconnect harness connector C310A. See RESTRAINTS CONTROL MODULE (RCM) under REMOVAL & INSTALLATION. Measure resistance between ground and component side of RCM connector C310A, terminal No. 15. See Fig 1 . If resistance is more than 10 k/ohms, repair short to ground in Black/Yellow wire. See WIRING DIAGRAMS . Go to step 10 . If resistance is less than 10 k/ohms, go to step 8 . - Check AIR BAG warning light circuit for open
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 C310A. Connect negative battery cable. Turn ignition switch to ON position. If AIR BAG warning light comes on, go to step 8 . If AIR BAG warning light does not come on, go to next step. - Check circuit for open
Turn ignition switch to OFF position. Access instrument cluster and disconnect harness connector C220A. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Turn ignition switch to ON position. Measure voltage between ground and harness side of instrument cluster connector C220A, terminal No. 2 (White/Light Blue wire, circuit No. 1112). See Figure . If voltage is more than 10 volts, go to next step. If voltage is less than 10 volts, repair open in White/Light Blue wire. See WIRING DIAGRAMS . Go to step 10 . - Check circuit for open
Turn ignition switch to OFF position. Measure resistance between harness side of RCM connector C310A, terminal No. 15 and harness side of instrument cluster connector C220A, terminal No. 1 (Black Yellow wire, circuit No. 608). If resistance is less than 0.5 ohm, repair or replace instrument cluster. Go to step 10 . If resistance is more than 0.5 ohm, repair open in Black Yellow wire. Go to step 10 .NOTE: Ensure all air bag system simulators, sensor electrical connectors and RCM electrical connectors are connected prior to carrying out on-demand self-test or erroneous faults may be set. - Confirm RCM fault
Turn ignition switch to OFF position. Reconnect RCM connector C310A and instrument cluster connector C220A. Turn ignition switch to ON position. Perform on-demand self-test. If DTC B1869 was retrieved during on-demand self-test replace RCM. Go to next step. If DTC B1869 was not retrieved during on-demand self-test, check for cause of intermittent short to ground or open in Black/Yellow wire. Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Repair any intermittent problems found. Go to next step. - Check for intermittent fault
Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC B1869 was retrieved during on-demand self-test and AIR BAG warning light does illuminate, go to step 2 . If DTC B1869 was retrieved during on-demand self-test and AIR BAG warning light does not illuminate, go to step 5 . If DTC B1869 was not retrieved during on-demand self-test, check for cause of intermittent short to ground or open in Black/Yellow wire (circuit No. 608). See WIRING DIAGRAMS . Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Activate other systems in the same wire harness. Repair any intermittent problems found. Go to next step. - Check for additional DTCs
Refer to continuous DTCs recorded in step 1 . If any continuous DTCs were retrieved, go to diagnostic trouble code identification table for direction to appropriate test. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table. DO NOT clear any DTCs until all DTCs have been resolved. If no DTCs were retrieved, reconnect air bag system. Activate air bag system. See ACTIVATING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear all DTCs. See CLEARING FAULT CODES under DIAGNOSTICS.