Circuit/System Testing
WARNING: This page is about a different car, the 2018 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition/Vehicle - Off
- Disconnect the electrical connector: X175@T12 Automatic Transmission Assembly
- Connect a test lamp between the test points: High Side Driver 1 - Control circuit terminal 18 & Ground
- Ignition - On / Vehicle - In Service Mode
- Perform the scan tool control function: High Side Driver 1 - On and Off
Verify the test lamp turns On and Off.
- If the test lamp is always Off
Refer to: DTC P0658, P0659, P2670, or P2671
- If the test lamp is always On
Refer to: DTC P0658, P0659, P2670, or P2671
- Go to next step: If the test lamp turns On and Off
- If the test lamp is always Off
- Remove - Test Lamp
- Ignition/Vehicle - Off
- Disconnect the electrical connector: K71 Transmission Control Module
- Ignition - On / Vehicle - In Service Mode
- Test for less than 1 V between the test points:
- { P2718, P2720, P2721 } Control circuit terminal 13 & Ground
- { P2727, P2729, P2730 } Control circuit terminal 14 & Ground
- { P281B, P281D, P281E } Control circuit terminal 1 & Ground
- If 1 V or greater
Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for infinite resistance between the test points:
- { P2718, P2720, P2721 } Control circuit terminal 13 & Ground
- { P2727, P2729, P2730 } Control circuit terminal 14 & Ground
- { P281B, P281D, P281E } Control circuit terminal 1 & Ground
- If less than infinite resistance
Repair the short to ground on the circuit.
- Go to next step: If infinite resistance
- Test for less than 2 ohms between the test points:
- { P2718, P2720, P2721 } Control circuit terminal 13 & The other end of the circuit
- { P2727, P2729, P2730 } Control circuit terminal 14 & The other end of the circuit
- { P281B, P281D, P281E } Control circuit terminal 1 & The other end of the circuit
- If greater than 2 ohms
Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 ohms
- Remove the component: Automatic Transmission Fluid Pan
- Connect the electrical connector: X175@T12 Automatic Transmission Assembly
- Disconnect the appropriate electrical connector:
- { P2718, P2720, P2721 } Q77D Transmission Control Solenoid Valve 4
- { P2727, P2729, P2730 } Q77E Transmission Control Solenoid Valve 5
- { P281B, P281D, P281E } Q77H Transmission Control Solenoid Valve 8
- Ignition - On / Vehicle - In Service Mode
- Test for less than 1 V between the test points:
- { P2718, P2720, P2721 } Control circuit terminal 17@Control module harness & Ground
- { P2727, P2729, P2730 } Control circuit terminal 1@Control module harness & Ground
- { P281B, P281D, P281E } Control circuit terminal 21@Control module harness & Ground
- If 1 V or greater
Replace the component: Automatic Transmission Wiring Harness
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for infinite resistance between the test points:
- { P2718, P2720, P2721 } Control circuit terminal 17@Control module harness & Ground
- { P2727, P2729, P2730 } Control circuit terminal 1@Control module harness & Ground
- { P281B, P281D, P281E } Control circuit terminal 21@Control module harness & Ground
- If less than infinite resistance
Replace the component: Automatic Transmission Wiring Harness
- Go to next step: If infinite resistance
- Test for less than 2 ohms between the test points:
- { P2718, P2720, P2721 } Control circuit terminal 17@Control module harness & The other end of the circuit
- { P2727, P2729, P2730 } Control circuit terminal 1@Control module harness & The other end of the circuit
- { P281B, P281D, P281E } Control circuit terminal 21@Control module harness & The other end of the circuit
- If greater than 2 ohms
Replace the component: Automatic Transmission Wiring Harness
- Go to next step: If less than 2 ohms
- Test or replace the component: Q77 Transmission Control Solenoid Valve