LEMON Manuals: Even more car manuals for everyone
Home >> Ford >> 2000 >> Contour SE, 2.0 3, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 270 (Air Bag Restraint Systems) >> Diagnostic Tests >> Test U: Front Crash Sensor Communications Fault (DTC B2227) >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2004 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.

Front crash sensor communication fault can be caused by damaged wiring, terminals or connectors, faulty front crash sensor, incorrect front crash sensor mounting or faulty RCM.

  1. Check for hard or intermittent DTC

    Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Retrieve and record any continuous DTCs. See RETRIEVING FAULT CODES  . Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC B2227 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B2227 was not retrieved, fault is intermittent. Go to step  12 .

  2. Inspect front crash sensor mounting & mounting surface

    Turn ignition switch to OFF position. Access front crash sensor. See FRONT CRASH SENSOR  under REMOVAL & INSTALLATION. Inspect front crash sensor for loose mounting bolts or harness connector. Remove front crash sensor. Inspect front crash sensor alignment tabs, harness connector and mounting surface for damage, corrosion or dirt. If problems are found, repair as necessary. Go to step  13 . If no problem are found, go to next step.

  3. Inspect front crash sensor ground circuit for high resistance

    Reinstall front crash sensor. Leave crash sensor harness connector disconnected. Measure resistance in Violet/Light Green wire (circuit No. 618) between front crash sensor case ground and harness side of front crash sensor connector. If resistance is less than 100 ohms, go to step  5 . If resistance is more than 100 ohms, go to next step.

  4. Check front crash sensor mounting

    Remove front crash sensor. Clean and repair front crash sensor mounting surface and bolts as necessary. Reinstall front crash sensor and connect harness connector. Turn ignition switch to ON position. Perform on-demand self-test. If DTC B2227 was retrieved during on-demand self-test, go to next step. If DTC B2227 was not retrieved, fault is corrected. Go to step  13 .

  5. Check circuits for short to voltage between front crash sensor & RCM

    Access RCM and disconnect harness connector C310B. Disconnect front crash sensor harness connector. Turn ignition switch to ON position. Measure voltage in Violet/Light Green wire between ground and harness side of front crash sensor connector. Measure voltage in Violet/Orange wire (circuit No. 617) between ground and harness side of front crash sensor connector. If voltage is less than 0.2 volt in either circuit, go to next step. If voltage is more than 0.2 volt in both circuits, repair short to voltage in appropriate wire. Go to step  13 .

  6. Check circuits for short to ground between front crash sensor & RCM

    Turn ignition switch to OFF position. Measure resistance in Violet/Light Green wire between ground and harness side of front crash sensor connector. Measure resistance in Violet/Orange wire (circuit No. 617) between ground and harness side of front crash sensor connector. If resistance is more than 10 k/ohms in both circuits, go to next step. If resistance is less than 10 k/ohms in either circuit, repair short to ground in appropriate wire. Go to step  13 .

  7. Check circuit for open between front crash sensor & RCM

    Turn ignition switch to OFF position. Measure resistance in Violet/Orange wire between harness side of RCM connector C310B, terminal No. 19 and harness side of front crash sensor connector. See Figure . If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Violet/Orange wire. Go to step  13 .

  8. Check circuit for open between front crash sensor & RCM

    Measure resistance in Violet/Light Green wire between harness side of RCM connector C310B, terminal No. 20 and harness side of front crash sensor connector. See Figure . If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Violet/Light Green wire. Go to step  13 .

  9. Check circuit for short between front crash sensor & RCM

    Measure resistance between Violet/Light Green wire and Violet/Orange wire on harness side of front crash sensor connector. If resistance is more than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short between Violet/Light Green wire and Violet/Orange wire. Go to step  13 .

  10. Check front crash sensor

    Install known good front crash sensor and connect harness connector. Reconnect RCM harness connector C310B. Perform on-demand self-test. If DTC B2227 was retrieved during on-demand self-test, go to step  11 . If DTC B2227 was not retrieved, fault is corrected. Go to step  13 .
    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.

  11. Confirm RCM fault

    Turn ignition switch to ON position. Perform on-demand self-test. If DTC B2227 was retrieved during on-demand self-test, replace RCM. Go to step  13 . If DTC B2227 was not retrieved during on-demand self-test, fault is intermittent. Attempt to recreate fault by flexing wire harness and cycling ignition frequently. See WIRING DIAGRAMS  . Activate other systems in same wire harness. Repair any intermittent problems found. Go to step  13 .

  12. Check for intermittent fault condition

    Perform on-demand self-test. If DTC B2227 was retrieved during on-demand self-test, go to step  2 . If DTC B2227 was not retrieved during on-demand self-test, attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. See WIRING DIAGRAMS  . Activate other systems in same wire harness. Repair any intermittent problems found. Go to step  13 .

  13. 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.
scientia non olet · About LEMON Manuals