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Home >> Ford >> 2002 >> Crown Victoria Base, 4.6 9 >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Inflatable Restraint System >> Diagnostic Tests >> Test T: Seat Track Position Sensor Circuit Open (DTC C1946) >> Possible Causes

Possible Causes

A seat track position sensor open circuit fault could be caused by damaged wiring, terminals or connectors, faulty seat track position sensor or faulty RCM.

  1. 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. 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 C1946 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC C1946 was not retrieved, fault is intermittent. Go to step  8 .

  2. Check circuit for open between left front seat & RCM

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access RCM and disconnect connector C310A. See RESTRAINTS CONTROL MODULE  under REMOVAL & INSTALLATION. Disconnect left front seat floor connector C311. Measure resistance between harness side RCM connector C310A, terminal No. 8 and vehicle harness side of left front seat floor connector C311, terminal No. 5 (Light Green wire, circuit No. 1520). See Figure & Figure . If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Light Green wire. See WIRING DIAGRAMS  . Go to step  9 .

  3. Check circuit for open between left front seat & RCM

    Measure resistance between harness side of RCM connector C310A, terminal No. 9 and vehicle harness side of left front seat floor connector C311, terminal No. 4 (Tan/Black wire, circuit No. 1558). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Tan/Black wire. Go to step  9 .

  4. Check circuit for open between left front seat & RCM

    Turn ignition switch to OFF position. Disconnect seat track position sensor connector. Measure resistance in Light Green wire between seat harness side of left front seat floor connector C311, terminal No. 5 and harness side of seat track position 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 Light Green wire. Go to step  9 .

  5. Check circuit for open between left front seat & RCM

    Measure resistance in Tan/Black wire between seat harness side of left front seat floor connector C311, terminal No. 4 and harness side of seat track position 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 Tan/Black wire. Go to step  9 .

  6. Check seat track position sensor

    Reconnect RCM connector C310A. Install known-good seat track position sensor. See SEAT TRACK POSITION SENSOR  under REMOVAL & INSTALLATION. Position left front seat in vehicle. Reconnect seat floor harness connector C311. Turn ignition switch to RUN position. Perform on-demand self-test. If DTC C1946 was retrieved during on-demand self-test, go to next step. If DTC C1946 was not retrieved, fault is corrected. Go to step  9 .
    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.

  7. Confirm RCM Fault

    Turn ignition switch to OFF position. Reinstall original seat track position sensor. Turn ignition switch to RUN position. Perform on-demand self-test. If DTC C1946 was retrieved during on-demand self-test, replace RCM. Go to step  9 . If DTC C1946 was not retrieved during on-demand self-test, fault is corrected. Go to step  9 .

  8. Check for intermittent fault

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC C1946 was retrieved during on-demand self-test, go to step  2 . If DTC C1946 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.

  9. 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. 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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