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Home >> Ford >> 2000 >> Focus LX, Standard >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System >> Diagnostic Tests >> Test U: Driver-Side Seat Belt PRETENSIONER Circuit Failure (DTC B1876) >> Possible Causes

Possible Causes

A driver-side seat belt pretensioner circuit out of range resistance could be caused by high or low resistance on Green/Blue wire (circuit 15S-JA33), high or low resistance on Black/Blue wire (circuit 91S-JA33), high or low resistance in driver-side seat belt pretensioner or an internal RCM fault.

  1. Check driver-side pretensioner

    Turn ignition off. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to RUN position. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B1876 is retrieved, go to next step. If DTC B1876 is not retrieved, replace driver-side seat belt pretensioner. See SEAT BELT PRETENSIONER  under REMOVAL & INSTALLATION. Activate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear DTCs. Repeat on-demand self-test.

  2. Check driver-side seat belt pretensioner circuits

    Turn ignition off. Access RCM and disconnect harness connector C423. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. Disconnect driver-side seat belt pretensioner simulator. Measure resistance of Green/Blue wire between RCM harness connector C423, terminal No. 11 and left under-seat connector C30, terminal No. 5. See Figure & Figure . Resistance should be less than 5 ohms. Measure resistance between ground and RCM harness connector C423, terminal No. 11 (Green/Blue wire). Resistance should be more than 10 k/ohms. If resistances are as specified, go to next step. If resistances are not as specified, repair Green/Blue wire as necessary. Activate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear DTCs. Repeat on-demand self-test.

  3. Check driver-side seat belt pretensioner circuits

    Measure resistance of Black/Blue wire between RCM harness connector C423, terminal No. 12 and left under-seat connector C30, terminal No. 6. If resistance is less than 5 ohms replace RCM. Activate air bag system. See ACTIVATING SYSTEM  under 6DISABLING & ACTIVATING AIR BAG SYSTEM. Clear DTCs. Repeat on-demand self-test. If resistance is more than 5 ohms, repair open in Black/Blue wire. Activate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear DTCs. Repeat on-demand self-test.
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