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:

Use the schematics and connector end views to identify the device's ground, B+, ignition, powertrain sensor bus enable, and serial data circuit terminals.

Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connectors at the K212 Gear Shift Control Module. It may take up to 10 min for all vehicle systems to power down.
Verify a test lamp illuminates between each of the ground circuit terminals and B+.
- If the test lamp does not illuminate
  Repair the open/high resistance in the ground circuit or ground connection.
- Go to next step: If the test lamp illuminates
Ignition ON/Vehicle In Service Mode.
If equipped, verify a test lamp illuminates between each of the B+ circuit terminals and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Test for an open/high resistance in the B+ circuit.
  - If an open/high resistance is found, repair the fault on the circuit.
  - Go to next step: If an open/high resistance is not found
2. Verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Test for a short to ground in the B+ circuit.
  - If a short to ground is found, repair the fault in the circuit.
  - Go to next step: If a short to ground is not found
2. Replace the K212 Gear Shift Control Module.
- Go to next step: If the test lamp illuminates
If equipped, verify a test lamp illuminates between each of the ignition circuit terminals, which has a fuse in the circuit, and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Test for an open/high resistance in the ignition circuit.
  - If an open/high resistance is found, repair the fault in the circuit.
  - Go to next step: If an open/high resistance is not found
2. Verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Test for a short to ground in the ignition circuit.
  - If a short to ground is found, repair the fault in the circuit.
  - Go to next step: If a short to ground is not found
2. Replace the K212 Gear Shift Control Module.
- Go to next step: If the test lamp illuminates
If equipped, verify a test lamp illuminates between the powertrain sensor bus enable circuit terminal and ground.
- If the test lamp does not illuminate
1. Ignition/Vehicle OFF, remove the test lamp, disconnect the harness connectors at the K20 Engine Control Module.
2. Test for less than 2 Ω in the powertrain sensor bus enable circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K20 Engine Control Module.
- Go to next step: If the test lamp illuminates
Test for less than 4.5 V between each of the CAN Bus 3 serial data circuit terminals and ground.
- If 4.5 V or greater
  Refer to Scan Tool Does Not Communicate with Device on CAN 3 to test for a short to voltage.
- Go to next step: If less than 4.5 V
Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 10 min for all vehicle systems to power down.
Test for greater than 100 Ω between each of the CAN Bus 3 serial data circuit terminals and ground.
- If 100 Ω or less
  Refer to Scan Tool Does Not Communicate with Device on CAN 3 to test for a short to ground.
- Go to next step: If greater than 100 Ω
Disconnect the harness connectors at the device setting the DTC.
Test for less than 2 Ω in each of the CAN Bus 3 serial data circuits end to end between the K212 Gear Shift Control Module and the device setting the DTC.
- If 2 Ω or greater
  Repair the open/high resistance in the serial data circuit.
- Go to next step: If less than 2 Ω
Replace the K212 Gear Shift Control Module.