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Home >> Ford >> 2000 >> Taurus LX, 3.0 2, AX4N >> Repair and Diagnosis >> External Pages >> Different car >> Section 34 (Air Bag Restraint Systems) >> Diagnostic Tests >> Test Q: Right Side Crash Sensor Communication Fault (DTC U2018) >> Possible Causes

Possible Causes

WARNING: This page is about a different car, the 2002 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

A right side crash sensor communication fault could be caused by damaged Yellow/Violet wire (circuit No. 7-JA40), damaged Brown/White wire (circuit No. 9-JA40) or damaged right side crash sensor.

  1. Check for hard or intermittent 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 DIAGNOSTIC TROUBLE CODES (DTCS)  under DIAGNOSTICS. Clear continuous DTCs. See CLEARING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC U2018 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC U2018 was not retrieved, fault is intermittent. Go to step  9 .

  2. Check harness connector

    Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access right side crash sensor. See SIDE CRASH SENSOR  under REMOVAL & INSTALLATION. Visually check side crash sensor harness connection. If side crash sensor harness connector is connected to sensor correctly, go to next step. If side crash sensor harness connector is not properly connected to sensor, attach sensor harness connector correctly. Go to step  10 .

  3. Check for open circuit

    Access and disconnect RCM harness connector C310B. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. See Figure . Disconnect right side crash sensor harness connector. Measure resistance of Yellow/Violet wire between RCM harness connector C310B, terminal No. 10 and right side crash sensor harness connector. If resistance is more than 10 k/ohms, repair open in Yellow/Violet wire. See WIRING DIAGRAMS  . Go to step  10 . If resistance is less than 10 k/ohms, go to next step.

  4. Check for open circuit

    Measure resistance of Brown/White wire between RCM harness connector C310B, terminal No. 11 and right side crash sensor harness connector. If resistance is more than 10 k/ohms, repair open in Brown/White wire. Go to step  10 . If resistance is less than 10 k/ohms, go to next step.

  5. Check for short to ground

    Disconnect RCM connector C310A. Measure resistance between RCM harness connectors C310B, terminal No. 10 (Yellow/Violet wire) and C310A, terminal No. 21 (Black/Red wire, circuit No. 31-JA10A). If resistance is less than 10 k/ohms, repair short to ground in Yellow/Violet wire. Go to step  10 . If resistance is more than 10 k/ohms, go to next step.

  6. Check for short to ground

    Measure resistance between RCM harness connectors C310B, terminal No. 11 (Brown/White wire) and C310A, terminal No. 21 (Black/Red wire). If resistance is less than 10 k/ohms, repair short to ground in Brown/White wire. Go to step  10 . If resistance is more than 10 k/ohms, go to next step.

  7. Check for short to voltage

    Turn ignition switch to RUN position. Measure voltage between ground and RCM harness connector C310B, terminal No. 10 (Yellow/Violet wire). If voltage is less than 0.2 volt, go to next step. If voltage is more than 0.2 volt, repair short to voltage in Yellow/Violet wire. Go to step  10 .

  8. Check for short to voltage

    Measure voltage between ground and RCM harness connector C310B, terminal No. 11 (Brown/White wire). If voltage is less than 0.2 volt, go to next step. If voltage is more than 0.2 volt, repair short to voltage in Brown/White wire. Go to step  10 .

  9. Check for intermittent fault

    Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC U2018 was retrieved during on-demand self-test, go to step  2 . If DTC U2018 was not retrieved during on-demand self-test, check for cause of intermittent communication fault. Attempt to recreate fault by flexing wire harness and cycling ignition switch frequently. Repair any intermittent problems found. Go to next step.

  10. 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 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.
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