Tail, Marker, and License Lamps Always On

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

Tail, Marker, and License Lamps Always On Diagnostic Test

Step	Action	Yes	No
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System
1	Did you perform the Lighting Systems Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - Lighting Systems
2	Verify that the tail, marker and license lamps are always on. Do the tail, marker and license lamps operate normally?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Remove the park lamp relay. Do the park lamps turn OFF?	Go to Step 4	Go to Step 9
4	Ensure that the headlamp switch is in the OFF position and there is sufficient light to the ambient light sensor. Test for a ground signal at the park lamp relay control circuit terminal in the body relay block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present?	Go to Step 5	Go to Step 10
5	Use the scan tool to check the body control module (BCM) park lamp switch input data. Does the scan tool indicate a park lamps OFF request signal?	Go to Step 8	Go to Step 6
6	Test for a short to ground in the park lamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 7
7	Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 11
8	Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 12
9	Repair the short to voltage in one of the following circuits. Refer to Wiring Repairs in Wiring Systems: The park lamp supply voltage The tail lamp supply voltage The license lamp supply voltage The marker lamp supply voltage Did you complete the repair?	Go to Step 13	-
10	Replace the park lamp relay. Refer to Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair?	Go to Step 13	-
11	Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair?	Go to Step 13	-
12	IMPORTANT: Perform the setup procedure for the BCM. Replace the body control module (BCM). Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?	Go to Step 13	-
13	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3