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Home >> Cadillac >> 2017 >> CTS V >> Repair and Diagnosis >> External Pages >> Different car >> Section 237 (Automatic Transmission - 8L45 (M5N) Or 8L90 (M5U) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P171A-P171C: Transmission Fluid Pressure Accumulator Solenoid Valve Control Circuit >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2016 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON.
  2. Verify a test lamp illuminates on both test points of the circuit fuse.
    • If the test lamp does not illuminate on either test point of the fuse 

      Refer to .

    • If the test lamp illuminates on 1 test point and the fuse is open 
    1. Ignition OFF, remove the test lamp.
    2. Test for infinite resistance between the ignition circuit and ground.
      NOTE: There are multiple ignition circuits protected by this fuse.
      • If less than infinite resistance, repair the short to ground on the circuit.
    • If the test lamp illuminates on both test points of the circuit fuse 
  3. Ignition OFF, disconnect the X175 harness connector at the T12 Automatic Transmission Assembly, ignition ON.
  4. Verify a test lamp illuminates between the ignition circuit terminal 2 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF, remove the test lamp.
    2. Test for less than 2 Ω in the ignition circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the X50A Fused Block-Underhood.
    • If the test lamp illuminates 
  5. Verify that a test lamp does not illuminate between the ignition circuit terminal 2 and the control circuit terminal 8.
    • If the test lamp illuminates 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K20 Engine Control Module.
    • If the test lamp does not illuminate 
  6. Remove the test lamp.
  7. Verify the scan tool Transmission Fluid Pressure Accumulator Solenoid Valve Control Circuit High Voltage Test Status parameter is OK when commanding the Transmission Fluid Pressure Accumulator Solenoid Valve ON with a scan tool.
    • If OK is not displayed 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K20 Engine Control Module.
    • If OK is displayed 
  8. Install a 3 A fused jumper wire between the control circuit terminal 8 and the ignition circuit terminal 2.
  9. Verify the scan tool Transmission Fluid Pressure Accumulator Solenoid Valve Control Circuit High Voltage Test Status parameter is Malfunction when commanding the Transmission Fluid Pressure Accumulator Solenoid Valve On with a scan tool.
    • If Malfunction is not displayed 
    1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module.
    2. Test for less than 2 Ω in the control 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 Malfunction is displayed 
  10. Perform the Component Testing.
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