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Home >> Ford >> 2000 >> Excursion 7.3 F, 4WD >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System - Excursion & Super Duty >> Diagnostic Tests >> Test S: Air Bag Tone Warning Indicator Circuit Short To Battery Or Ignition (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 Light Blue/Black wire or damaged or inoperative GEM.

  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 ECS and disconnect harness connector. See ELECTRONIC CRASH SENSOR  under REMOVAL & INSTALLATION. Turn ignition switch to RUN position. Measure resistance between ECS harness connector terminals No. 13 (Light Blue/Black wire) and No. 17 (Red/White wire). If resistance is less than 10 k/ohms, repair short to battery in Light Blue/Black wire and go to step  5. If resistance is more than 10 k/ohms, go to next step.

  3. Check air bag tone warning indicator

    Turn ignition off. Access and disconnect 12-pin instrument cluster connector C250A. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect driver-side air bag simulator. Reconnect ECS harness connector. Reconnect negative battery cable. Turn ignition to RUN position. Listen for audible warning tone. If tone was heard within one minute, go to step  5. If tone was not heard within one minute, replace ECS. 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 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 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. Prove out system. Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.
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