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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 198 (Manual Transmission - TREMEC 6-Speed (M3L Mg9)) >> Diagnostic Information and Procedures >> DTC P086A-P086D: Neutral Position Sensor >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B209 Neutral Position Sensor. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
    • If 5 Ω or greater 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Test for less than 2 Ω in the low reference circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If less than 5 Ω 
  3. Ignition ON.
  4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the 5 V reference circuit and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance.
    3. Test for less than 2 Ω in the 5 V reference circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module. Ignition ON.
    2. Test for less than 1 V between the 5 V reference circuit and ground.
      • If 1 V or greater, repair the short to voltage in the circuit.
      • If less than 1 V, replace the K20 Engine Control Module.
    • If between 4.8-5.2 V 
  5. Ignition ON.
  6. Verify the scan tool Neutral Position Sensor parameter displays In-Gear.
    • If the parameter does not display In-Gear 
    1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module. Ignition ON.
    2. Test for less than 1 V between the signal circuit terminal 3 and ground.
      • If 1 V or greater, repair the short to voltage in the circuit.
      • If less than 1 V, replace the K20 Engine Control Module.
    • If the parameter displays In-Gear 
  7. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the signal circuit terminal 3.
  8. Verify the scan tool Neutral Position Sensor parameter displays Neutral.
    • If the parameter does not display Neutral 
    1. Ignition OFF, disconnect X1 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the signal circuit terminal 3 and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance.
    3. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
    4. Test for less than 2 Ω on the signal circuit, end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 Engine Control Module.
      • If the parameter does display Neutral 
  9. Replace the B209 Neutral Position Sensor.
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