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Home >> Ford >> 2000 >> Contour SE, 2.0 3, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 204 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> Test U: Left PRETENSIONER Circuit Short To Battery Or Ignition (DTC B1878) >> Possible Causes

Possible Causes

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

A short to battery or ignition in left seat belt pretensioner circuit could be caused by short to battery or ignition in Light Green/Red wire (circuit No. 1079), short to battery or ignition in Light Green/Black wire (circuit No. 1080), short to battery or ignition in left seat belt pretensioner, or RCM internal fault.

  1. Check for hard or intermittent DTCs

    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 DTCs. See RETRIEVING FAULT CODES  . Clear continuous DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B1878 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B1878 was not retrieved, fault is intermittent. Go to step  4 .

  2. Check left seat belt pretensioner

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to RUN position. Perform on-demand self-test. If DTC B1878 was retrieved during on-demand self-test, go to next step. If DTC B1878 was not retrieved during on-demand self-test, replace left seat belt pretensioner. See SEAT BELT PRETENSIONERS  under REMOVAL & INSTALLATION. Go to step  5 .

  3. Check left seat belt pretensioner circuits

    Turn ignition switch to OFF position. Access and disconnect RCM connector. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Measure voltage between ground and RCM harness connector terminals No. 18 (Light Green/Red wire) and No. 22 (Light Green/Black wire) individually. See Figure . If voltage is more than 0.2 volt at either terminal, repair short to battery or ignition in Light Green/Red or Light Green/Black wires. See WIRING DIAGRAMS  . Go to step  5 . If voltage is less than 0.2 volt at both terminals, replace RCM. 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 in Light Green/Red or Light Green/Black wires. See WIRING DIAGRAMS  . 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. 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. Perform system operation check. See SYSTEM OPERATION CHECK  . Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.
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