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Home >> Ford >> 2000 >> Taurus LX, 3.0 2, AX4N >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System >> Diagnostic Tests >> Test B: Air Bag Tone Warning Indicator Circuit Short To Battery (DTC B1891) >> Possible Causes

Possible Causes

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

  1. Check for hard or intermittent DTC

    Ensure ignition is off. Connect scan tool to 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 off. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Leave negative battery cable disconnected. Access RCM and disconnect harness connector C201C. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. Access and disconnect GEM connector C201C. See GENERIC ELECTRONIC MODULE (GEM)  under REMOVAL & INSTALLATION. Turn ignition switch to RUN position. Measure resistance between RCM harness connector C310A, terminals No. 11 (Light Blue/Black wire) and No. 1 (White/Yellow wire). See Figure . If resistance is less than 10 k/ohms, repair short to battery or ignition voltage in Light Blue/Black wire. Go to step  5 . If resistance is more than 10 k/ohms, go to next step.

  3. Check air bag tone warning indicator circuit

    Ensure ignition is off. Measure resistance between RCM harness connector C310A, terminal No. 11 (Light Blue/Black wire) and GEM harness connector C201C, terminal No. 16 (Light Blue/Black wire). See Figure & Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair high resistance on Light Blue/Black wire, then go to step  6 .

  4. Check air bag tone warning indicator

    Ensure ignition is off. Reconnect GEM harness connector. Reconnect negative battery cable. Turn ignition switch to RUN position. Connect fused jumper lead between ground and RCM harness connector C310A, terminal No. 11 (Light Blue/Black wire). If GEM generates a tone, replace RCM and go to step  6 . If GEM does not generate a tone replace GEM and go to step  6 .

  5. Check for intermittent fault

    Refer to continuous DTCs recorded in step  1 . If DTC retrieved in step  1 was a intermittent fault, check for cause of intermittent short to ground or open circuit on Light Blue/Black wire. Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Repair any intermittent problems found. Go to next step. If DTC retrieved in step  1 was not a intermittent fault, go to next step.

  6. 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. If no DTCs were retrieved, reconnect air bag system. Activate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Prove out system. Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.
    Fig 1: Identifying Generic Electronic Module (GEM) Harness Connector
    G99A00158Courtesy of FORD MOTOR CO.
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