Component 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.

Perform the Circuit/System Testing first.
Ignition Off, remove the fluid pan from the T12 Automatic Transmission Assembly.
Disconnect the harness connector at the Q77D Transmission Control Solenoid Valve 4. Refer to Transmission Solenoid Information .
Connect a jumper wire between terminal 1 and terminal 2 of the Q77D Transmission Control Solenoid Valve 4 harness connector.
Disconnect the X176 harness connector.
Test for less than 2 Ω on X176 connector terminal 4 and terminal 9.
- If greater than 2 Ω
  Replace the transmission control wiring harness.
- If less than 2 Ω
Disconnect the jumper wire.
Remove the automatic transmission wiring harness, electrical connector passage sleeve.
Connect a jumper wire between X176 harness connector terminal 4 and terminal 9.
Test for less than 2 Ω between X175 connector terminal 13 and terminal 18.
- If greater than 2 Ω
  Replace the automatic transmission wiring harness, electrical connector passage sleeve.
- If less than 2 Ω
Test for 4.5-5.5 Ω at 20°C (68°F) between terminal 1 and terminal 2 on the Q77D Transmission Control Solenoid Valve 4.
- If not between 4.5-5.5 Ω
  Replace the Q77D Transmission Control Solenoid Valve 4.
- If between 4.5-5.5 Ω
Test for infinite resistance on the Q77D Transmission Control Solenoid Valve 4, as listed below:
- Solenoid terminal 1 and ground
- Solenoid terminal 2 and ground
- If not infinite resistance
  Replace the Q77D Transmission Control Solenoid Valve 4.
- If infinite resistance
Replace the K71 Transmission Control Module.