Possible Causes

A left seat belt pretensioner circuit short to battery fault can be caused by damaged wiring, terminals or connectors, faulty left seat belt pretensioner or faulty RCM.

1. Check for hard or intermittent DTC
   
   Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). 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 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 pretensioner
   
   Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Disconnect left seat belt pretensioner harness connector C323. Access RCM and disconnect harness connector C310B. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Turn ignition switch to ON position. Measure voltage between ground and harness side of RCM connector terminal No. 24 (Light Green/Red wire). See Figure . Measure voltage between ground and harness side of RCM connector terminal No. 23 (Light Green/Black wire). If voltage is more than 0.2 volt in either circuit, repair short to battery in appropriate wire. See WIRING DIAGRAMS  . Go to step  5 . If voltage is less than 0.2 volt in both circuits, go to next step.
   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.
3. Confirm RCM fault
   
   Turn ignition switch to OFF position. Reconnect left seat belt pretensioner harness connector C323. Reconnect RCM connector C310B. Turn ignition switch to ON position. Perform on-demand self-test. If DTC B1878 was retrieved during on-demand self-test, replace RCM. Go to step  5 . If DTC B1878 was not retrieved during on-demand self-test, fault is intermittent. Go to next step.
4. Check for intermittent fault
   
   Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC B1878 was retrieved during on-demand self-test, check for cause of intermittent faults in Light Green/Red and Light Green/Black wires. See WIRING DIAGRAMS  . Repair any intermittent faults found. If intermittent faults are found and corrected, go to next step. If intermittent faults are not found, go to step  2 . If DTC B1878 was not retrieved during on-demand self-test, attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Repair any intermittent problems found. 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 continuous 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.