Circuit/System Verification

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.

Ignition ON.

NOTE:

A low or high voltage DTC may set in multiple control modules due to a concern with the battery or charging system.

Verify there are no system voltage DTCs set as current or history in any control module.
- If any system voltage DTCs are set
  Diagnose these DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Go to next step: If not system voltage DTCs are set
Ignition Off and all vehicle systems OFF.

NOTE:

The battery voltage should stabilize after a few minutes of turning the ignition/vehicle Off.

Verify the battery voltage is between 12.4 V to 12.8 V at the C1 Battery.
- If not between the specified range
  Refer to Battery Inspection/Test
- Go to next step: If between the specified range
Start the engine with all accessories off, allow the system voltage to stabilize.
Test for 13 V to 15 V at the C1 Battery.
- If not the specified value
  Refer to Charging System Test
- Go to next step: If between the specified range
Verify DTC P129B or P129C is set as current.
- If DTC P129B or P129C is set as current
  Refer to Circuit/System Testing.
- Go to next step: If DTC P129B or P129C is not set as current
A fault is not currently present and may be an intermittent condition. Refer to Diagnostic Instructions.