Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Unfortunately, this system does not work much like the old ones, with just power and grounds through the door switches. The lamps are also controlled by the driver door module and the passenger door module and the body control module. Most of the testing for the system requires the use of a class 2 scanner to run function tests on the system. The system still relies on grounds to turn on, but the grounding is now done through the control modules. I'm sending the diagnostic procedure, just in case you have access to a class 2 scanner. Wondering if the truck might still be covered by warranty?
Schematic Reference: Interior Lights Schematics or Body Control System Schematics in Body Control System
Connector End View Reference: Lighting Systems Connector End Views , Body Control System Connector End Views in Body Control System or Master Electrical Component List in Wiring Systems
Did you perform the Lighting Systems Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Lighting Systems
Verify that the courtesy/dome lamps are inoperative.
Do the courtesy/dome lamps operate normally?
Go to Testing for Intermittent and Poor Connections in Wiring Systems
Go to Step 3
Are all courtesy lamps inoperative?
Go to Step 5
Go to Step 4
Test the voltage supply and ground circuits of the inoperative lamp for an open or high resistance. Refer to Circuit Testing and Wiring Repairs In Wiring Systems.
Did you find and correct the condition?
Go to Step 16
Go to Step 14
Are the courtesy lamps inoperative from a specific switch only?
Go to Step 6
Go to Step 11
Inspect the following related body control module (BCM), driver door module (DDM), passenger door module (PDM) data parameters, and check for a ground signal on the liftgate ajar signal circuit of the BCM with the liftgate open. Refer to Scan Tool Data List and Scan Tool Data Definitions for typical values and definitions:
Was a problem found?
Go to Step 7
Go to Step 10
Disconnect and test the switch of the affected input circuit for proper continuity in the open and closed positions. Refer to Testing for Continuity in Wiring Systems.
Is continuity correct in both positions?
Go to Step 8
Go to Step 9
Test the signal and ground circuits of the affected input circuit for the following conditions:
Inspect for poor connections at the harness connector of the affected switch. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Go to Step 12
Inspect for poor connections at the harness connector of the module in the affected circuit. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Go to Step 13
Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Go to Step 15
Replace the switch in the affected circuit.
Did you complete the replacement?
Perform the setup procedure for the replacement module as applicable.
Replace the module in the affected circuit. Refer to the appropriate replacement procedure:
Replace the inoperative bulb.
Did you complete the repair?
Perform the setup procedure for the BCM.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.
Operate the system in order to verify the repair.
Did you correct the condition?