Headlamps Always On - Low or High Beam
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
Headlamps Always On - Low or High Beam
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views |
|||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Place the headlamp switch in the OFF position. Do the high and low beam headlamps operate normally? |
Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 | Are only the high beam headlamps always ON? | Go to Step 4 | Go to Step 8 |
| 4 | Disconnect the headlamp dimmer switch. Do the high beam headlamps remain ON? |
Go to Step 5 | Go to Step 10 |
| 5 | Test the following circuits for a short to ground as applicable. Refer to Circuit Testing
and Wiring Repairs
.
Did you find and correct a condition? |
Go to Step 18 | Go to Step 6 |
| 6 | Remove the HI HEADLAMP-LT and HI HEADLAMP-RT fuses from the underhood fuse block. Do the high beam headlamps remain ON? |
Go to Step 12 | Go to Step 7 |
| 7 | With a scan tool, monitor the High Beam Relay Command data parameter in the body control module (BCM) data list. Does the scan tool display On? |
Go to Step 11 | Go to Step 15 |
| 8 | Remove the HID-LT and HID-RT fuses from the underhood fuse block. Do the low beam headlamps remain always ON? |
Go to Step 13 | Go to Step 9 |
| 9 | With a scan tool, monitor the Low Beam Relay Command data parameter in the body control module (BCM) data list. Does the scan tool display On? |
Go to Step 11 | Go to Step 16 |
| 10 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
Go to Step 18 | Go to Step 17 |
| 11 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
Go to Step 18 | Go to Step 14 |
| 12 | Repair the short to voltage in the right or left high beam headlamp supply voltage circuit. Refer to Wiring Repairs
. Did you find and correct a condition? |
Go to Step 18 | - |
| 13 | Repair the short to voltage in the right or left low beam headlamp supply voltage circuit. Refer to Wiring Repairs
. Did you find and correct a condition? |
Go to Step 18 | - |
| 14 | Replace the BCM. Refer to Control Module References
for replacement, setup, and programming. Did you complete the replacement? |
Go to Step 18 | - |
| 15 | Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement
. Did you complete the repair? |
Go to Step 18 | - |
| 16 | Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement
. Did you complete the repair? |
Go to Step 18 | - |
| 17 | Replace the headlamp dimmer switch. Refer to Turn Signal Multifunction Switch Replacement
. Did you complete the repair? |
Go to Step 18 | - |
| 18 | Operate the system in order to verify the repair. Did you correct the condition? |
System OK | Go to Step 3 |