Possible Causes
WARNING: This page is about a different car, the 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
OCS circuit fault could be caused by damaged wiring, terminals or connectors, faulty OCS module, faulty OCS mat sensor, faulty OCS pressure transducer or faulty RCM.
- 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. Retrieve, flag and record any continuous Diagnostic Trouble Codes (DTCs). See RETRIEVING FAULT CODES under DIAGNOSTICS. Flag DTC B2290. See BIT-MAPPED DIAGNOSTIC TROUBLE CODES under DIAGNOSTICS. Retrieve and record any flagged DTCs. Perform on-demand self-test. See ON-DEMAND SELF-TEST under DIAGNOSTICS. Retrieve and record any flagged DTCs. If flagged fault "?" was retrieved during on-demand self-test, multiple faults exist and all steps of diagnostic procedure must be performed. If DTC B2290 was retrieved during on-demand self-test, fault is hard.- For communication (COMM) fault, go to next step.
- For internal (INT) fault, go to step 12 .
- For calibration fault, replace OCS system. See OCCUPANT CLASSIFICATION SENSOR (OCS) under REMOVAL & INSTALLATION. Go to step 12 .
- For sensing element fault, replace OCS system and go to step 12 .
- If DTC B2290 was not retrieved during on-demand self-test, fault is intermittent. Go to step 11 .
- Check ignition circuit for open
Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. DO NOT remove right front seat at this time. Disconnect OCS connector C3159A from OCS electronic control module. Turn ignition switch to RUN position. Measure voltage between ground and OCS connector C3159A, terminal No. 4 (Violet/Orange wire, circuit No. 298). See Fig 1 . If voltage is 9-16 volts, go to next step. If voltage is not 9-16 volts, repair open in Violet/Orange wire. See WIRING DIAGRAMS . Go to step 12 . - Check ground circuit for open
Turn ignition switch to OFF position. Measure resistance between ground and OCS connector C3159A, terminal No. 9 (Pink/Orange wire, circuit No. 676). See Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Pink/Orange wire. Go to step 12 . - Check for short to ground between OCS & RCM
Access and disconnect both RCM connectors. See RESTRAINTS CONTROL MODULE (RCM) under REMOVAL & INSTALLATION. Measure resistance between ground and OCS connector C3159A, terminal No. 5 (Dark Green/Violet wire, circuit No. 1556). Measure resistance between ground and OCS connector C3159A, terminal No. 10 (Dark Blue/Orange wire, circuit No. 1557). If resistance in both circuits is more than one megohm, go to next step. If resistance in either circuit is less than one megohm, repair short to ground in appropriate wire. Go to step 12 . - Check for short to battery between OCS & RCM
Turn ignition switch to RUN position. Measure voltage between ground and OCS connector terminal No. 5 (Dark Green/Violet wire). Measure voltage between ground and OCS connector terminal No. 10 (Dark Blue/Orange wire). If voltage in both circuits is less than 0.2 volt, go to next step. If voltage in either circuit is more than 0.2 volt, repair short to battery in appropriate wire. Go to step 12 . - Check for open circuit between OCS & RCM
Turn ignition switch to OFF position. Measure resistance between harness side of RCM connector C310A, terminal No. 1 and OCS connector C3159A, terminal No. 5. (Dark Green/Violet wire). See Figure & Fig 1 . If resistance is less than 0.24 ohm, go to next step. If resistance is more than 0.24 ohm, repair open in Dark Green/Violet wire. Go to step 12 . - Check for open circuit between OCS & RCM
Ensure ignition switch is in OFF position. Measure resistance in Dark Blue/Orange wire between harness side of RCM connector C310A, terminal No. 2 and OCS connector C3159A, terminal No. 10. If resistance is less than 0.24 ohm, go to next step. If resistance is more than 0.24 ohm, repair open in Dark Blue/Orange wire. Go to step 12 . - Check for short circuit between OCS & RCM
Measure resistance between harness side of RCM connector C310A, terminal No. 1 (Dark Green/Violet wire) and OCS connector C3159A, terminal No. 10 (Dark Blue/Orange wire). If resistance is less than one megohm, go to next step. If resistance is more than one megohm, repair short between Dark Green/Violet and Dark Blue/Orange wires. Go to step 12 . - Check OCS
Ensure ignition switch is in OFF position. Reconnect both RCM connectors. Install a known-good OCS system. Turn ignition switch to RUN position. Using scan tool, rezero OCS. Perform on-demand self-test. Flag DTC B2290. Retrieve and record any flagged faults. If any faults were flagged against OCS, go to next step. If no faults were flagged against OCS, fault was corrected. Go to step 12 .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. - Confirm RCM fault
Turn ignition switch to OFF position. Ensure both RCM connectors are connected. Perform on-demand self-test. Flag DTC B2290. Retrieve and record any flagged faults. If DTC B2290 was retrieved during on-demand self-test and "?" was flagged by scan tool, perform entire diagnostic test before replacing RCM. Replace RCM. Go to step 12 . If DTC B2290 was not retrieved during on-demand self-test, fault is corrected. Go to step 12 . - Check for intermittent fault
Turn ignition to OFF position. Disable air bag system. See DISABLING SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to ON position. Perform on-demand self-test. If DTC B2290 was retrieved during on-demand self-test, fault is hard. If flagged fault "?" was retrieved during on-demand self-test in step 1 , multiple faults exist and all steps of diagnostic procedure must be performed.- For communication (COMM) fault, go to step 2 .
- For internal (INT) fault, go to step 12 .
- For calibration fault, replace OCS system. See OCCUPANT CLASSIFICATION SENSOR (OCS) under REMOVAL & INSTALLATION. Go to step 12 .
- For sensing element fault, replace OCS system and go to step 12 .
If DTC B2290 was not retrieved during on-demand self-test, check for cause of intermittent fault. Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Repair any intermittent problems found. Go to next step.
- 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. DO NOT clear any DTCs until all DTCs have been resolved. If no 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.