Headlamp Low or High Beams Always On
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
Headlamp Low or High Beams Always On
| 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 high beam relay. Do the high beam headlamps remain ON? |
Go to Step 12 | Go to Step 7 |
| 7 | Test for a ground signal at the high beam relay control circuit connector terminal. Refer to Circuit Testing
. Is a ground control signal present? |
Go to Step 11 | Go to Step 15 |
| 8 | Remove the low beam relay. Do the low beam headlamps remain always ON? |
Go to Step 13 | Go to Step 9 |
| 9 | Test for a ground signal at the headlamp low beam relay control circuit connector terminal of the relay. Refer to Circuit Testing
. Is a ground signal present? |
Go to Step 11 | Go to Step 16 |
| 10 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing
and Wiring 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 Circuit Testing
and Wiring 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 high beam headlamp relay. Refer to Relay Replacement (Attached to Wire Harness)
or Relay Replacement (Within an Electrical Center)
. Did you complete the repair? |
Go to Step 18 | - |
| 16 | Replace the low beam relay. Refer to Relay Replacement (Attached to Wire Harness)
or Relay Replacement (Within an Electrical Center)
. 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 |