Possible Causes

High resistance between RCM housing ground and terminal ground could be caused by improper tightening of RCM mounting bolts, high resistance in RCM logic grounds or RCM internal fault.

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 DTCs. See RETRIEVING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B1921 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B1921 was not retrieved, fault is intermittent. Go to step  6 .
2. Check mounting of RCM
   
   Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access and remove RCM. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Inspect RCM, mounting bracket and mounting surface for damage or corrosion. Inspect RCM bracket bolts are fully seated and tightened properly. If bracket and mounting surface is okay and mounting bolts were tight, go to next step. If bracket and mounting surface is not okay and/or mounting bolts were not tight, repair/replace as necessary. Install RCM and go to step  7 .
3. Check RCM harness connection
   
   Ensure RCM connector C2041A is fully connected. If RCM connector C2041A is fully connected, go to next step. If RCM connector C2041A is not fully connected, reattach connector. Go to step  7 .
4. Check vehicle chassis ground
   
   Measure resistance between a known good ground and RCM mounting surface. If resistance more than 100 ohms, repair grounding system and go to step  7 . If resistance is less than 100 ohms, go to next step.
5. Check ground circuit for open
   
   Ensure ignition switch is in OFF position. Disconnect RCM connector C2041A. Measure resistance between chassis ground near RCM and RCM connector C2041A, terminal No. 21 (Black wire, circuit No. 57). See Figure . If resistance is more than 100 ohms, repair open in Black wire and go to step  7 . See WIRING DIAGRAMS  . If resistance is less than 100 ohms, replace RCM. Go to next step.
6. 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 high resistance in Black wire. 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.
7. 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. DO NOT clear any DTCs until all DTCs have been resolved. See DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION  table. If no continuous DTCs were retrieved, reconnect air bag system. Reactivate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Prove out system. See PROVE OUT SYSTEM  under DIAGNOSTICS. Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.