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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 AE: Left Seat Belt PRETENSIONER Open Or Low Resistance (DTC B1877 Or B1885) >> Possible Causes

Possible Causes

Left seat belt pretensioner circuit open or low resistance could be caused by open or high resistance in Light Green/Red wire (circuit 1079) or Light Green/Black wire (circuit 1080), Light Green/Red and Light Green/Black wires shorted together, pretensioner internal fault or RCM internal fault.

  1. Check for hard or intermittent DTCs

    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. Clear continuous DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B1877 was retrieved during on-demand self-test, go to next step. If DTC B1885 was retrieved during on-demand self-test, go to step  5 . If DTC B1877 or B1885 was not retrieved, fault is intermittent. Go to step  8 .

  2. Disable & recheck DTCs

    Turn ignition off. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Connect fused jumper wire between Light Green/Red and Light Green/Black wires on vehicle harness side of driver"s seat 10-pin connector. Perform on-demand self-test. If DTC B1877 was retrieved, go to next step. If DTC B1877 was not retrieved, go to step  4 .
    NOTE: An extremely low resistance is expected for the following test. Zero ohmmeter before taking measurement.

  3. Check harness for high resistance

    Turn ignition off. Access and disconnect RCM harness connector C310B. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. Measure resistance between RCM harness connector C310B, terminals No. 15 (Light Green/Red wire) and No. 16 (Light Green/Black wire). See Figure . If resistance is more than 0.5 ohm, repair high resistance in Light Green/Red and/or Light Green/Black wire between RCM harness connector and under-seat connector. Go to step  9 . If resistance is less than 0.5 ohm, replace RCM. Go to step  9 .
    NOTE: An extremely low resistance is expected for the following test. Zero ohmmeter before taking measurement.

  4. Check in-seat harness for high resistance

    Turn ignition off. Access and disconnect left seat belt pretensioner 4-pin connector. See SEAT BELT PRETENSIONER  under REMOVAL & INSTALLATION. Connect fused jumper wire between Light Green/Red and Light Green/Black wires on in-seat harness side of seat belt pretensioner 4-pin connector. Measure resistance between Light Green/Red and Light Green/Black wires on 10-pin in-seat harness connector. If resistance is more than 0.5 ohm, replace in-seat harness. Go to step  9 . If resistance is less than 0.5 ohm, replace left seat belt pretensioner. Go to step  9 .

  5. Check DTCs

    Turn ignition off. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC B1885 was retrieved, go to next step. If DTC B1885 was not retrieved, go to step  7 .
    NOTE: An extremely low resistance is expected for the following test. Zero ohmmeter before taking measurement.

  6. Check vehicle harness for low resistance

    Turn ignition off. Access and disconnect RCM harness connector C310B. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. Measure resistance between RCM harness connector C310B, terminals No. 15 (Light Green/Red wire) and No. 16 (Light Green/Black wire). See Figure . If resistance is less than 1.7 ohms, repair low resistance/short in Light Green/Red and/or Light Green/Black wire between RCM harness connector and under-seat connector. Go to step  9 . If resistance is more than 1.7 ohms, replace RCM. Go to step  9 .
    NOTE: An extremely low resistance is expected for the following test. Zero ohmmeter before taking measurement.

  7. Check in-seat harness for low resistance

    Turn ignition off. Access and disconnect left seat belt pretensioner 4-pin connector. See SEAT BELT PRETENSIONER  under REMOVAL & INSTALLATION. Measure resistance between Light Green/Red and Light Green/Black wires on 10-pin in-seat harness connector. If resistance is less than 1.7 ohms, replace in-seat harness. Go to step  9 . If resistance is more than 1.7 ohms, replace left seat belt pretensioner. Go to step  9 .

  8. 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 high or low resistance in seat belt pretensioner circuit loop. 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.

  9. 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.
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