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, connect the X175 harness connector.
Remove the fluid pan from the T12 Automatic Transmission.
Disconnect the harness connector at the following solenoids listed below. Refer to Transmission Solenoid Information .
- Q77A Transmission Control Solenoid Valve 1
- Q77B Transmission Control Solenoid Valve 2
- Q77C Transmission Control Solenoid Valve 3
- Q77F Transmission Control Solenoid Valve 6
- Q77G Transmission Control Solenoid Valve 7
- Q77J Transmission Control Solenoid Valve 9
Ignition On.
Command the high side driver 2 Off.
Connect a test lamp between terminal 2 and ground on each solenoid harness connector for the following solenoids listed below:
- Q77A Transmission Control Solenoid Valve 1
- Q77B Transmission Control Solenoid Valve 2
- Q77C Transmission Control Solenoid Valve 3
- Q77F Transmission Control Solenoid Valve 6
- Q77G Transmission Control Solenoid Valve 7
- Q77J Transmission Control Solenoid Valve 9
Verify the test lamp does not illuminate.
- If the test lamp illuminates
1. Disconnect the X176 harness connector.
2. Verify a test lamp does not illuminate between the ignition circuit terminal 18 and ground.
  - If the test lamp illuminates
    Replace the automatic transmission wiring harness, electrical connector passage sleeve.
  - If the test lamp does not illuminate
    Replace the transmission control wiring harness.
- If the test lamp does not illuminate
Connect a test lamp between terminal 2 and ground on each solenoid harness connector for the following solenoids listed below:
- Q77A Transmission Control Solenoid Valve 1
- Q77B Transmission Control Solenoid Valve 2
- Q77C Transmission Control Solenoid Valve 3
- Q77F Transmission Control Solenoid Valve 6
- Q77G Transmission Control Solenoid Valve 7
- Q77J Transmission Control Solenoid Valve 9
Verify the test lamp turns On and Off when commanding the high side driver 2 On and Off with a scan tool for each of the following solenoids listed below:
- Q77A Transmission Control Solenoid Valve 1
- Q77B Transmission Control Solenoid Valve 2
- Q77C Transmission Control Solenoid Valve 3
- Q77F Transmission Control Solenoid Valve 6
- Q77G Transmission Control Solenoid Valve 7
- Q77J Transmission Control Solenoid Valve 9
- If the test lamp is always Off
1. Ignition Off, disconnect the X176 harness connector.
2. Connect a test lamp between terminal 18 and ground on the automatic transmission wiring harness, electrical connector passage sleeve.
3. Verify the test lamp turns On and Off when commanding the high side driver 2 On and Off.
  - If the test lamp is always Off
    Replace the automatic transmission wiring harness, electrical connector passage sleeve.
  - If the test lamp turns On and Off
    Replace the transmission control wiring harness.
- If the test lamp turns On and Off
Disconnect the test lamp.
Test for 4.5-5.5 Ω between the ignition terminal 2 and the control terminal 1 on the following solenoids:
- Q77A Transmission Control Solenoid Valve 1
- Q77B Transmission Control Solenoid Valve 2
- Q77C Transmission Control Solenoid Valve 3
- Q77F Transmission Control Solenoid Valve 6
- Q77G Transmission Control Solenoid Valve 7
- If not between 4.5-5.5 Ω
  Replace the solenoid that is not between 4.5-5.5 Ω.
- If between 4.5-5.5 Ω
Test for 11.0-13.0 Ω between the ignition terminal 2 and the control terminal 1 on the Q77J Transmission Control Solenoid Valve 9.
- If not between 11.0-13.0 Ω
  Replace the Q77J Transmission Control Solenoid Valve 9.
- If between 11.0-13.0 Ω
Test for infinite resistance between each ignition terminal 1 and ground and then each control terminal 2 and ground on the following solenoids:
- Q77A Transmission Control Solenoid Valve 1
- Q77B Transmission Control Solenoid Valve 2
- Q77C Transmission Control Solenoid Valve 3
- Q77F Transmission Control Solenoid Valve 6
- Q77G Transmission Control Solenoid Valve 7
- Q77J Transmission Control Solenoid Valve 9
- If not infinite resistance
  Replace the solenoid that has continuity to ground.
- If infinite resistance
All OK.