Circuit/System Testing
WARNING: This page is about a different car, the 2020 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition/Vehicle & All vehicle systems - Off
- Disconnect the electrical connector:M40 Rear Compartment Lid Latch
- Verify a test lamp illuminates between ground circuit terminal 2 and B+.
- If the test lamp does not illuminate
- Repair the open/high resistance on circuit 1650 or the ground connection.
- Go to next step: If the test lamp illuminates
- Connect a test lamp between the test points:Control circuit terminal 1 & ground
- Ignition - On / Vehicle - In Service Mode
- Operate the component:E7 Rear License Plate Lamp - Pressed
Verify the test lamp state:
Not used=Test lamp Off
Pressed=Test lamp flashes ON and OFF
- If the test lamp is always OFF
- Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
- Test for infinite resistance between the control 6128 and 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 Ω in the control 6128 end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module
- If the test lamp is always ON
- Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
- Test for less than 1 V between the control 6128 and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K9 Body Control Module
- Go to next step: If the test lamp turns ON and OFF
- Test or replace the component:M40 Rear Compartment Lid Latch
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.