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 Wiring Schematics to verify the items listed below:
- The control module's Fuses, Relays, B+ supply voltages, ignition voltages, and ground circuits.
- The control module terminal numbers.

Ignition OFF, and all vehicle systems OFF, disconnect the appropriate harness connector at the control module setting the DTC.
Test for less than 1 V between the ignition circuit terminal and ground.
- If 1 V or greater
1. Verify the KR73 Ignition Main Relay Coil Control circuit 5199 is not shorted to voltage.
  - If a short to voltage is found repair the short to voltage
  - Go to next step: If a short to voltage is not found
Repair the Short to voltage on the ignition circuit.
- Go to next step: If less than 1 V
Ignition ON vehicle in Run or Propulsion mode.
Verify a test lamp illuminates between the appropriate module ignition circuit terminal and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF remove the test lamp.
2. Test for less than 2 Ω in the ignition circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, refer to Power Mode Mismatch .
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF remove the test lamp
2. Test for infinite resistance between the ignition circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - Go to next step: If Infinite Resistance
3. Replace the appropriate control module.
- Go to next step: If the test lamp illuminates
Replace the appropriate control module setting the DTC.