Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

Ignition/Vehicle & All vehicle systems - Off
Disconnect the electrical connector: X175 @ T12 Automatic Transmission Assembly
Ignition - On / Vehicle - In Service Mode
Test for 8.3 to 9.6 V between the test points: 9 V Reference circuit terminal 27 @ Component harness & Ground
NOTE:
Testing for steps 4.1 to 8.7 is performed on the control module K71 side of the harness connector.
- If less than 8.3 V
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K71 Transmission Control Module
3. Test for infinite resistance between the test points: 9 V Reference circuit terminal 27 @ Component harness & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
4. Test for less than 2 ohms between the test points: 9 V Reference circuit terminal 27 @ Component harness & The other end of the circuit @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component: K71 Transmission Control Module
- If greater than 9.6 V
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K71 Transmission Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points: 9 V Reference circuit terminal 8 @ Control module harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - If less than 1 V - Replace the component: K71 Transmission Control Module
- Go to next step: If between 8.3 and 9.6 V
Ignition/Vehicle - Off
Install - EL-38522 Variable Signal Generator
- Voltage - 5 V
- Frequency - 300 Hz
- Duty Cycle - 50%
- Black lead @ Ground
- Red lead @ Signal circuit terminal 26
Ignition - On / Vehicle - In Service Mode
Verify the scan tool parameter: Input Shaft Speed Sensor = 250 to 270 RPM
- If not between 250 and 270 RPM
1. Ignition/Vehicle - Off
2. Disconnect the electrical connector: K71 Transmission Control Module
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points: Signal circuit terminal 26 @ Component harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
5. Ignition/Vehicle - Off
6. Test for infinite resistance between the test points: Signal circuit terminal 26 @ Component harness & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
7. Test for less than 2 ohms between the test points: Signal circuit terminal 26 @ Component harness & The other end of the circuit @ Control module harness
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Replace the component: K71 Transmission Control Module
- Go to next step: If between 250 and 270 RPM
Ignition/Vehicle - Off
Connect the electrical connector.X175 @ T12 Automatic Transmission Assembly
Remove the component: Automatic Transmission Fluid Pan
Disconnect the electrical connector: X177
Ignition - On / Vehicle - In Service Mode
Test for 8.3 to 9.6 V between the test points: 9 V Reference circuit terminal 4 & Signal circuit terminal 5 @ Component harness
- If not between 8.3 and 9.6 V
  Replace the component: Automatic Transmission Wiring Harness
- Go to next step: If between 8.3 and 9.6 V
Replace the component: B14C Transmission Input Shaft Speed Sensor