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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 269 (Air Bag Restraint Systems) >> Diagnostic Tests >> Test V: Seat Position Sensor Circuit Fault (DTC C1981) >> Possible Causes

Possible Causes

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

A seat position sensor resistance out of range fault could be caused by damaged wiring, terminals or connectors, faulty seat 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 ON position. Retrieve and record any continuous Diagnostic Trouble Codes (DTCs). See RETRIEVING FAULT CODES  under DIAGNOSTICS. Perform on-demand self-test. See ON-DEMAND SELF-TEST  under DIAGNOSTICS. If DTC C1981 was retrieved during on-demand self-test, fault is hard. Go to next step. If DTC C1981 was not retrieved, fault is intermittent. Go to step  10 .

  2. Check circuits for short to voltage

    Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access RCM and disconnect connector C310B. See RESTRAINTS CONTROL MODULE (RCM)  under REMOVAL & INSTALLATION. Measure voltage between ground and harness side of RCM connector C310B, terminal No. 23 (Yellow/Red wire, circuit No. 7-JA53). See Figure . Measure voltage between ground and harness side of RCM connector C310B, terminal No. 23 (Brown/Red wire, circuit No. 7-JA53). If voltage is less than 0.2 volt in both circuits, go to next step. If voltage is more than 0.2 volt in either circuit, repair short to battery in appropriate wire. See WIRING DIAGRAMS  . Go to step  11 .

  3. Check circuit for open

    Turn ignition switch to OFF position. Measure resistance between harness side of RCM connector C310B, terminal No. 23 and main harness side of left front seat connector C315, terminal No. 2 (Yellow/Red wire). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Yellow/Red wire. Go to step  11 .

  4. Check circuit for open

    Measure resistance between harness side of RCM connector C310B, terminal No. 24 and main harness side of left front seat connector C315, terminal No. 3 (Brown/Red wire, circuit No. 7-JA53). If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Brown/Red wire. Go to step  11 .

  5. Check circuits for short to voltage

    Disconnect seat position sensor harness connector from sensor. Position left front seat in vehicle and connect under-seat harness connectors. DO NOT activate air bag system at this time. Turn ignition switch to ON position. Measure voltage between ground and harness side of RCM connector C310B, terminal No. 23 (Yellow/Red wire). Measure voltage between ground and harness side of RCM connector C310B, terminal No. 23 (Brown/Red wire). If voltage is less than 0.2 volt in both circuits, go to next step. If voltage is more than 0.2 volt in either circuit, repair short to battery in appropriate wire. Go to step  11 .

  6. Check circuit for open

    Turn ignition switch to OFF position. Measure resistance in Yellow/Red wire between harness side of RCM connector C310B, terminal No. 23 and seat harness side of seat position sensor connector. If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Yellow/Red wire. Go to step  11 .

  7. Check circuit for open

    Measure resistance in Brown/Red wire between harness side of RCM connector C310B, terminal No. 23 and seat harness side of seat position sensor connector. If resistance is less than 0.5 ohm, go to next step. If resistance is more than 0.5 ohm, repair open in Brown/Red wire. Go to step  11 .

  8. Check seat position sensor

    Connect connector C310B. Install a known-good seat position sensor. Perform on-demand-self-test. If DTC C1981 was retrieved during on-demand self-test, go to next step. If DTC C1981 was not retrieved, fault is corrected. Go to step  11 .
    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.

  9. Confirm RCM fault

    Turn ignition switch to OFF position. Install original seat position sensor. Perform on-demand-self-test. If DTC C1981 was retrieved during on-demand self-test, replace RCM. Go to step  11 . If DTC C1981 was not retrieved during on-demand self-test, fault is corrected. Go to step  11 .

  10. Check for intermittent DTC

    Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform on-demand self-test. If DTC C1981 was retrieved during on-demand self-test, go to step  2 . If DTC C1981 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.

  11. 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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