Electrical Components

1999 Mercury Sable LS, 4D Sedan, 3.0 SSECTION Electrical Components
  • Fuse No. 6 (10-amp) or fuse No. 11 (15-amp).
  • Loose or damaged connections.
  • Brake Pedal Position (BPP) switch connections.
  • Wiring harness.
NOTE: See appropriate wiring diagram to diagnose electrical circuits and identify fuses and circuit numbers. See WIRING DIAGRAMSΒ  .

  1. Check Brakelight Operation

    Depress brake pedal. If brakelights illuminate, go to step Β 7 . If brakelights do not illuminate, go to next step.
  2. Check Fuse No. 11 (15-Amp)

    Check fuse No. 11 (15-amp), in fuse panel. See WIRING DIAGRAMSΒ  . If fuse is okay, go to step Β 4 . If fuse is blown, go to next step.
  3. Check Circuit No. 10 For Short To Ground

    Turn ignition off. Disconnect BPP switch connector. Using DVOM, measure resistance between BPP switch harness connector terminal No. 1 (Light Green/Red wire) and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in Light Green/Red wire between fuse No.11 and BPP switch. Reconnect all connectors and retest system.
  4. Check Circuit No. 10 For Open

    Using DVOM, measure resistance between fuse No. 11 output side terminal and BPP switch harness connector terminal No. 1 (Light Green/Red wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Light Green/Red wire between fuse No. 11 and BPP switch. Reconnect all connectors and retest system.
  5. Check BPP Switch

    Using DVOM, measure and record resistance between both BPP switch connector terminals. Apply brakes and recheck resistance. Resistance should be more than 10 k/ohms without brake pedal applied and 5 ohms or less with brake pedal applied. If resistance is as specified, go to next step. If resistance is not as specified, replace BPP switch and retest system.
  6. Check CircuitNo. 511 For Short To Ground

    Disconnect shift lock actuator 3-pin connector. Using DVOM, measure resistance between shift lock actuator harness connector terminal No. 1 (Light Green wire) and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in Light Green wire between BPP switch connector and shift lock actuator connector. Reconnect all connectors and retest system.
  7. Check Circuit No. 511 For Open

    Using DVOM, measure resistance of Light/Green wire between BPP switch harness connector terminal No. 2 and shift lock actuator harness connector terminal No. 1. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Light Green wire between BPP switch connector and shift lock actuator connector. Reconnect all connectors and retest system.
  8. Check Voltage To Shift Interlock Actuator

    Turn ignition on. Using DVOM, measure voltage between shift lock actuator harness connector terminal No. 3 (Purple/Orange wire) and ground. If battery voltage is not present, go to next step. If battery voltage is present, go to step Β 12 .
  9. Check Fuse No. 6 (10-Amp)

    Turn ignition off. Remove and check fuse No. 6 (10-amp). See WIRING DIAGRAMSΒ  . If fuse is blown, go to next step. If fuse is okay, go to step Β 11 .
  10. Check Circuit No. 298 For Short To Ground

    Using DVOM, measure resistance between shift lock actuator harness connector terminal No. 3 (Purple/Orange wire) and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair open in Purple/Orange wire between fuse No. 6 and shift lock actuator connector. Reconnect all connectors and retest system.
  11. Check Circuit No. 298 For Open

    Using DVOM, measure resistance between fuse No. 6 output terminal and shift lock actuator harness connector terminal No. 3 (Purple/Orange wire). If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Purple/Orange wire between fuse No. 6 and shift lock actuator connector. Reconnect all connectors and retest system.
  12. Check Circuit No. 57 For Open

    Using DVOM, measure resistance between shift lock actuator harness connector terminal No. 2 (Black wire) and ground. If resistance is 5 ohms or less, replace shift lock actuator. Reconnect all connectors and retest system. If resistance is more than 5 ohms, repair open in Black wire between shift lock actuator connector and ground.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.