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Home >> Ford >> 2002 >> Taurus SES, 3.0 S >> Repair and Diagnosis >> External Pages >> Different car >> Section 219 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> Test O: Left Seat Belt Buckle Switch Circuit Fault (DTC B2691) >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2003 Mercury Sable and 2003 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.

A left seat belt buckle switch open circuit or short to battery fault could be caused by damaged wiring, terminals, connectors, faulty seat belt buckle switch 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 Diagnostic Trouble Codes (DTCs). See RETRIEVING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B2691 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B2691 was not retrieved, fault is intermittent. Go to step  12 .

  2. Check for open between RCM and left front seat

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Ensure left front seat is removed. Access RCM and disconnect harness connector C310B. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Disconnect air bag simulator from left front under-seat harness connector. Measure resistance between harness side of RCM connector C310B, terminal No. 25 and harness side of left front under-seat connector C313F, terminal No. 3 (Brown/Light Blue wire, circuit No. 85). See Figure & Figure . If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Brown/Light Blue wire. See WIRING DIAGRAMS  . Go to step  13 .

  3. Check circuit for open

    Measure resistance between ground and harness side of left front under-seat connector C313F, terminal No. 3 (Black/Light Blue wire, circuit No. 1203). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Black/Light Blue wire. Go to step  13 .

  4. Check circuit for short to voltage

    Turn ignition switch to RUN position. Measure voltage between ground and harness side of left front under-seat connector C313F, terminal No. 3 (Black/Light Blue wire, circuit No. 1203). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Black/Light Blue wire. Go to step  13 .

  5. Check circuit for short to voltage

    Measure voltage between ground and harness side of left front under-seat connector C313F, terminal No. 4 (Black/Light Blue wire). If voltage is less than 0.2 volt, go to next step. If voltage is more than 0.2 volt, repair short to voltage in Black/Light Blue wire. Go to step  13 .

  6. Check circuit for open between left front seat & left front seat belt buckle

    Turn ignition switch to OFF position. Disconnect left front seat belt buckle connector C381. Measure resistance between harness side of left front in-seat connector C313M, terminal No. 3 and harness side of left front seat belt buckle connector C381, terminal No. 2 (Brown/Light Blue wire). See Figure & Figure . If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, replace left front in-seat harness. Go to step  13 .

  7. Check circuit for open between left front seat & left front seat belt buckle

    Measure resistance between harness side of left front in-seat connector C313M, terminal No. 4 and harness side of left front front seat belt buckle connector C381, terminal No. 4 (Brown/Light Blue wire). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, replace left front in-seat harness. Go to step  13 .

  8. Check left front in-seat harness circuit for short

    Measure resistance between harness side of left front in-seat harness connector C313M, terminal No. 3 (Brown/Light Blue wire) and all other pins in connector. If resistance is more that one megohm at all pins, go to next step. If resistance is less than one megohm at any pin, replace left front in-seat harness. Go to step  13 .

  9. Check left front in-seat harness circuit for short

    Measure resistance between harness side of left front in-seat harness connector C313M, terminal No. 4 (Black/Orange wire, circuit No. 649) and all other pins in connector. If resistance is more that one megohm at all pins, go to next step. If resistance is less than one megohm at any pin, replace left front in-seat harness. Go to step  13 .

  10. Check seat belt buckle switch

    Reconnect left front seat belt buckle switch connector. With left front seat belt buckled, measure resistance between harness side of in-seat harness connector C313M, terminals No. 3 (Brown/Light Blue wire) and No. 4 (Black/Orange wire). With left front seat belt unbuckled, again measure resistance between harness side of in-seat harness connector C313M, terminals No. 3 (Brown/Light Blue wire) and No. 4 (Black/Orange wire). If resistance is 248-455 ohms with left front seat belt buckled and 725-1282 ohms with left front seat belt unbuckled, go to next step. If resistance is not 248-455 ohms with left front seat belt buckled and 725-1282 ohms with left front seat belt unbuckled, replace left front seat belt buckle. Go to step  13 .
    NOTE: Ensure all air bag system simulators, sensor electrical connectors and RCM electrical connectors are connected prior to carrying out on-demand self-test or erroneous faults may be set.

  11. Confirm RCM fault

    Turn ignition switch to OFF position. Disconnect air bag simulator from right front under-seat harness connector. Disconnect right and left front seat belt buckle harness connectors at buckles. Install front seat(s). DO NOT activate air bag system at this time. Install Air Bag Simulators (418-F395/014-R1079) on harness side of right and left front seat belt buckle harness connectors. Reconnect right and left front under-seat harness connectors. Reconnect RCM harness connector C310B. Perform on-demand-self-test. If DTC B2691 was retrieved during on-demand self-test, replace RCM. Go to step  13 . If DTC B2691 was not retrieved during on-demand self-test, fault is corrected. Go to step  13 .

  12. Check for intermittent DTC

    Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC B2691 was retrieved during on-demand self-test, go to step  2 . If DTC B2691 was not retrieved during on-demand self-test, check for cause of intermittent fault. Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Repair any intermittent problems found. Go to next step.

  13. 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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