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Home >> GMC >> 2021 >> Terrain SLE, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 91 (Automatic Transmission - 9T45 (M3U) Or 9T50 (M3D M3H) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P189C >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2020 GMC Terrain and 2020 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector at one of the following control modules:
    • B110 Battery Sensor Module
    • G10 Cooling Fan Motor
    • K173 Transmission Range Control Module
    • K20 Engine Control Module
    • M96A Active Grille Air Shutter 1 Actuator
  3. Ignition - On / Vehicle - In Service Mode
  4. Verify DTC P189C is not set.
    • If the DTC is not set after disconnecting a module from the circuit 

      Replace the component disconnected last.

    • If the DTC is set and there are modules connected to the circuit 

      Disconnect a component and repeat step 4.

    • Go to next step: If the DTC is set and all modules are disconnected from the circuit 
  5. Disconnect the electrical connector: K71 Transmission Control Module
  6. Test for less than 1 V between the test points: Serial Data circuit terminal 31 @ K71 Transmission Control Module & The other end of the circuit @ S3 Transmission Shift Lever
    • If greater than 1 V 

      Repair the short to voltage on the circuit.

    • Go to next step: If less than 1 V 
  7. Test for infinite resistance between the test points: Serial Data circuit terminal 31 @ K71 Transmission Control Module & Ground
    • If less than infinite resistance 

      Repair the short to ground on the circuit.

    • Go to next step: If infinite resistance 
  8. Test for less than 10 ohms between the test points: Serial Data circuit terminal 31 @ K71 Transmission Control Module & The other end of the circuit @ S3 Transmission Shift Lever
    • If greater than 10 ohms 

      Repair the open/high resistance in the circuit.

    • Go to next step: If less than 10 ohms 
  9. Replace the component: K71 Transmission Control Module