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Home >> Ford >> 2000 >> ZX2 Automatic >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System >> Diagnostic Tests >> Test P: Air Bag Tone Warning Indicator Circuit Short To Battery Or Ignition (DTC B1891) >> Possible Causes

Possible Causes

Air bag tone warning indicator circuit shorted to battery or ignition voltage could be caused by short to battery or ignition voltage in Gray wire or damaged or inoperative TWS module.

  1. 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 ECS module and disconnect harness connector. See ELECTRONIC CRASH SENSOR  under REMOVAL & INSTALLATION. Turn ignition switch to RUN position. Measure resistance between ECS module harness connector terminals No. 13 (Gray wire) and No. 17 (White wire). If resistance is more than 10 k/ohms, replace TWS module and go to next step. TWS module is attached to rear of instrument panel fuse block. If resistance is less than 10 k/ohms, repair short to battery voltage in Gray wire. Go to step  5 .

  2. Check for hard or intermittent DTC

    Ensure ignition is off. Connect NGS tester to DLC. See USING NGS TESTER  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 .

  3. Check air bag tone warning indicator

    Disconnect White 10-pin instrument cluster connector. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect driver-side air bag simulator. Reconnect ECS module connector. Connect negative battery cable. Turn ignition to RUN position. Listen for audible warning tone. Allow at least one minute for sequence of tones to sound. If warning tone was heard within one minute, go to step  5 . If warning tone was not heard within one minute, replace ECS module. Go to step  5 .

  4. Check for intermittent fault

    Refer to continuous DTCs recorded in step  1 . If DTC retrieved in step  1 was an intermittent fault, check for cause of intermittent short to battery or ignition voltage on Gray wire. Attempt to recreate fault by driving vehicle, 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 an intermittent fault, 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. If no continuous 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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