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Home >> Ford >> 2002 >> Crown Victoria Base, 4.6 9 >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System >> Diagnostic Tests >> Test D: Air Bag Tone Warning Indicator Circuit Short To Battery (DTC B1891) >> Possible Causes

Possible Causes

Air bag tone warning indicator circuit short to battery could be caused by short to battery in Light Blue/Black wire, damaged or inoperative LCM or faulty RCM.

  1. 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 RUN position. Retrieve and record any continuous DTCs. See RETRIEVING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B1891 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B1891 was not retrieved, fault is intermittent. Go to step  4 .

  2. Check air bag tone warning indicator circuit

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access RCM and disconnect connector C310B. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. Access LCM and disconnect connector C2145A. See LIGHTING CONTROL MODULE (LCM)  under REMOVAL & INSTALLATION. Turn ignition switch to RUN position. Measure voltage between ground and harness side of RCM connector C310B, terminal No. 11 (Light Blue/Black wire, circuit No. 1083). See Figure . 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 Light Blue/Black wire. See WIRING DIAGRAMS  . Go to step  5 .

  3. Check air bag tone warning indicator

    Turn ignition switch to OFF position. Reconnect LCM connector C2145A. Connect fused jumper wire between ground and harness side of RCM connector C310B, terminal No. 11 (Light Blue/Black wire). Turn ignition switch to RUN position. If air bag warning tone is heard, replace RCM. Go to step  5 . If air bag warning tone is not heard, replace LCM. Go to step  5 .

  4. Check for intermittent fault

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC B1891 was retrieved during on-demand self-test, go to step  2 . If DTC B1891 was not retrieved during on-demand self-test, check for cause of intermittent short to battery in Light Blue/Black wire (circuit No. 1083). See WIRING DIAGRAMS  . Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. 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 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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