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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 270 (Air Bag Restraint Systems) >> Diagnostic Tests >> Test C: Air Bag Warning Light Short To Battery (DTC B1870) >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2004 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.

AIR BAG warning light short to battery could be caused by damaged wiring, terminals or connectors, faulty instrument cluster or faulty RCM.

  1. Check for hard or intermittent DTC

    Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). 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 B1870 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B1870 was not retrieved, fault is intermittent. Go to step  4 .

  2. Check Black/Yellow wire for short to battery

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access instrument cluster and disconnect connector C220A. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. See Figure . Turn ignition switch to ON position. Measure voltage between ground and harness side of instrument cluster connector C220A, terminal No. 3 (Black/Yellow wire, circuit No. 608). If voltage is less than 0.2 volt, go to next step. If voltage is more than 0.2 volt, repair short to battery in Black/Yellow wire. See WIRING DIAGRAMS  . Go to step  5 .
    NOTE: Due to open circuit in Black/Yellow wire, DTC B1869 should be retrieved when carrying out on-demand self-test in next step. DTC B1870 should not be retrieved at this time.

  3. Check RCM

    Turn ignition switch to ON position. Perform on-demand self-test. If DTC B1870 was retrieved during on-demand self-test, replace RCM. Go to step  5 . If DTC B1870 was not retrieved during on-demand self-test, repair or replace instrument cluster. Go to step  5 .

  4. Check for intermittent fault

    Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC B1870 was retrieved during on-demand self-test, go to step  2 . If DTC B1870 was not retrieved during on-demand self-test, check for cause of intermittent problem 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 same wire harness. Repair any intermittent problems found. Go to next step.

  5. 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 (DTC) 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.
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