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 or replace as necessary. Go to step  7 .
3. Check RCM harness connection
   
   Ensure RCM connector C2005 is fully connected. If RCM connector C2005 is fully connected, go to next step. If RCM connector C2005 is not fully connected, reconnect 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. 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 harness connector C2005. Measure resistance between chassis ground and harness side of RCM connector C2005, terminal No. 21 (Black/Orange wire, circuit No. 649). See Figure . If resistance is more than 100 ohms, repair open in Black/Orange wire. See WIRING DIAGRAMS  . Go to step  7 . 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/Orange 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. Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.