Headlamps Always On - Low or High Beam
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.
Headlamps Always On - Low or High Beam Diagnostic Test
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System or Wiper/Washer System Connector End Views in Wiper/Washer Systems |
|||
| 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 high or low beam headlamps are always on. Do the high and low beam headlamps operate normally? |
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Does the wiper activated headlamp (WAH) function of the wiper system operate normally? | Go to Step 6 | Go to Step 4 |
| 4 | With the key in RUN and the wiper switch in the OFF position, use the scan tool to monitor the Front Wipers Active input parameter. Does the scan tool parameter display NO? |
Go to Step 14 | Go to Step 5 |
| 5 | Test the windshield wiper switch signal 2 circuit for a short to ground. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 22 | Go to Step 17 |
| 6 | Are only the high beam headlamps always on? | Go to Step 7 | Go to Step 11 |
| 7 | Disconnect the headlamp dimmer switch. Do the high beam headlamps remain always on? |
Go to Step 8 | Go to Step 13 |
| 8 | Test the following circuits for a short to ground as applicable. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems.
Did you find and correct a condition? |
Go to Step 22 | Go to Step 9 |
| 9 | Remove the high beam relay. Do the high beam headlamps remain always on? |
Go to Step 15 | Go to Step 10 |
| 10 | Test for a ground signal at the high beam relay control circuit connector terminal. Refer to Circuit Testing
in Wiring Systems. Is a ground control signal present? |
Go to Step 14 | Go to Step 19 |
| 11 | Remove the headlamp driver module (HDM). Do the low beam headlamps remain always on? |
Go to Step 16 | Go to Step 12 |
| 12 | Test for a voltage signal at the headlamp low beam relay control circuit connector terminal. Refer to Circuit Testing
in Wiring Systems. Is a voltage control signal present? |
Go to Step 14 | Go to Step 20 |
| 13 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 22 | Go to Step 21 |
| 14 | Inspect for poor connections at the harness connector of the Body Control Module (BCM). Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 22 | Go to Step 18 |
| 15 | Repair the short to voltage in the right or left high beam headlamp supply voltage circuit. Refer to Wiring Repairs
in Wiring Systems. Did you find and correct a condition? |
Go to Step 22 | - |
| 16 | Repair the short to voltage in the right or left low beam headlamp supply voltage circuit. Refer to Wiring Repairs
in Wiring Systems. Did you find and correct a condition? |
Go to Step 22 | - |
| 17 | Replace the wiper motor cover. Refer to Wiper Motor Cover Replacement
in Wipers/Washers Systems. Did you complete the repair? |
Go to Step 22 | - |
| 18 |
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 22 | - |
| 19 | Replace the high beam headlamp 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 22 | - |
| 20 | Replace the headlamp driver module (HDM). Refer to Relay Replacement (Within an Electrical Center)
or Relay Replacement (Attached to Wire Harness)
in Wiring Systems. Did you complete the repair? |
Go to Step 22 | - |
| 21 | Replace the headlamp dimmer switch. Refer toMultifunction, Turn Signal Switch Replacement
in Steering Wheel and Column. Did you complete the repair? |
Go to Step 22 | - |
| 22 | Operate the system in order to verify the repair. Did you correct the condition? |
System OK | Go to Step 3 |