Possible Causes

High resistance between ECS module housing ground and terminal ground can be caused by ECS module connected but not attached to right cowl mounting surface, poor attachment of ECS module due to loose mounting, dirt or corrosion at mounting surface or poor reference ground at terminals No. 18 and 21 (Black/Light Blue wire).

1. Check for continuous 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  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 ECS module mounting resistance
   
   Using scan tool, select PID/Data Monitor and Record. Select PID BRACKET. If resistance is more than one ohm, go to next step. If resistance is less than one ohm, replace ECS module. See ELECTRONIC CRASH SENSOR (ECS) MODULE  under REMOVAL & INSTALLATION. Go to step  6 .
3. Check vehicle chassis ground
   
   Access ECS module. See ELECTRONIC CRASH SENSOR (ECS) MODULE  under REMOVAL & INSTALLATION. Measure resistance between battery ground and mounting surface of ECS module. If resistance is more than one ohm, repair chassis ground as necessary. Go to step  6 . If resistance is less than one ohm, go to next step.
4. Check mounting of ECS
   
   Turn ignition switch to OFF position. Disconnect ECS module harness connector. Remove ECS module and inspect mounting surface for corrosion or dirt. If significant corrosion or dirt found, clean mounting surface, reinstall ECS module and go to step  6 . If no significant corrosion or dirt is found, go to next step.
5. Check ECS module terminal ground resistance
   
   Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access and disconnect ECS module harness connector. See ELECTRONIC CRASH SENSOR (ECS) MODULE  under REMOVAL & INSTALLATION. Measure resistance between ground and harness side of ECS module connector terminals No. 18 and 21 (Black/Light Blue wire) individually. See Figure . If resistance in either circuits is more than one ohm, repair appropriate Black/Light Blue wire. See WIRING DIAGRAMS  . Go to next step. If resistance in both circuits is less than one ohm, check for causes of intermittent high resistance. Attempt to recreate fault by flexing wire harness and cycling ignition frequently. Repair any intermittent problems found. If no intermittent problems are found, replace ECS module. 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 (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.