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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Automatic Transmission - 8L90 (M5U) - Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P182E Or P1915: Internal Mode Switch >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. 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 X175 harness connector at the T12 Automatic Transmission Assembly.
  2. Test for less than 5 Ω between the ground circuit terminal 30 and ground.
    • If 5 Ω or greater 
    1. Ignition Off, disconnect the harness connector at the K71 Transmission Control Module.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K71 Transmission Control Module.
    • Go to next step: If less than 5 Ω 
  3. Ignition On.
  4. Test for 8.3 - 9.3 V between the 9 V Reference 1 circuit terminal 31 and the 9 V Reference circuit 2 terminal 29 and ground.
    • If either circuit is greater than 9.3 V 
    1. Ignition Off, disconnect the harness connector at the K71 Transmission Control Module. Ignition On.
    2. Test for less than 1 V between the affected 9 V Reference circuit and ground.
      • If greater than 1 V, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K71 Transmission Control Module.
    • If either circuit is less than 8.3 V 
    1. Ignition Off, disconnect the harness connector at the K71 Transmission Control Module. Ignition On.
    2. Test for infinite resistance between the affected 9 V Reference circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the affected 9 V Reference circuit end to end.
      • If greater than 2 Ω, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K71 Transmission Control Module.
    • Go to next step: If both circuits are between 8.3 - 9.3 V 
  5. Verify the scan tool Internal Mode Switch A/B/C/P/S parameters display High.
    • If not High 
    1. Ignition Off, disconnected the harness connector at the K71 Transmission Control Module.
    2. Test for infinite resistance between the affected signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance replace the K71 Transmission Control Module.
    • Go to next step: If High 
  6. Install a 3 A fused jumper wire between the affected circuit and ground.
  7. Verify the scan tool affected circuit parameter displays Low.
    • If not Low 
    1. Ignition Off, remove the jumper wire, disconnect the harness connector at the K71 Transmission Control Module.
    2. Test for less than 1 V between the affected signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Test for less than 2 Ω in 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 K71 Transmission Control Module.
    • Go to next step: If Low 
  8. Test for 11 - 13 V at the signal circuit terminal 35 and ground.
    • If not between 11 - 13 V 
    1. Ignition Off, disconnect the X1 harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the harness connector X175 terminal 35 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 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.
    • Go to next step: If between 11 - 13 V 
  9. Connect a 3 A fused jumper wire between the signal circuit terminal 35 and the ground circuit terminal 30.
  10. Verify the scan tool Park/Neutral Position Switch parameter displays Park/Neutral.
    • If Park/Neutral is not displayed 

      Replace the K20 Engine Control Module.

    • Go to next step: If Park/Neutral is displayed 
  11. Perform the Component Testing.
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