Possible Causes

Resistance difference between RCM housing ground and terminal ground could be caused by improper seating of RCM retaining bolts, incorrect tightening torque of RCM mounting bolts or high resistance in RCM logic ground circuit.

1. Check for hard or intermittent DTC
   
   Ensure ignition is off. Connect scan tool to DLC. See USING SCAN TOOL  . 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  5 .
2. Check ground circuit for high resistance
   
   Turn ignition off. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access RCM and disconnect harness connector C310A. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. With negative battery cable connected, measure resistance between chassis ground and RCM connector C310A, terminal No. 10 (Black/Orange wire). See Figure . If resistance is more than 5 ohms, go to step  6 . If resistance is less than 5 ohms, go to next step.
3. Check chassis ground for high resistance
   
   With negative battery cable connected, measure resistance between RCM mounting bracket bolt and negative battery post. If resistance is more than 5 ohms, repair ground system as necessary. Go to step  6 . If resistance is less than 5 ohms, go to next step.
4. Check mounting of RCM
   
   Turn ignition off. Inspect RCM mounting bracket and mounting surface for damage, corrosion or dirt. Ensure RCM retaining bolts are fully seated and properly tightened. If RCM retaining bolts are fully seated and tightened properly and no damage, corrosion or dirt is present, replace RCM. Go to step  6 . If any damage or corrosion is found, clean, tighten bolts, and/or repair/replace as necessary. Go to step  6 .
5. Check for intermittent fault
   
   Refer to continuous DTCs recorded in step  1 . If DTC retrieved in step  1 was a intermittent fault, check for cause of high resistance in Black/Orange wire (circuit 649) or chassis ground system. 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 a intermittent fault, go to next step.
6. 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 IDENTIFICATION  table. If no DTCs were retrieved, reconnect air bag system. Reactivate air bag system. See ACTIVATING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Prove out system. Clear all DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS.