Headlamps Always On - Low or High Beam
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. 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 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 | 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 in Wiring Systems | 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
in Wiring Systems.
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
in Wiring Systems. 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
in Wiring Systems. 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
in Wiring Systems. 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
in Wiring Systems. 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
in Wiring Systems. 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
in Wiring Systems. Did you find and correct a condition? |
Go to Step 18 | - |
| 14 |
IMPORTANT:
Perform the setup procedure for the BCM. Replace the BCM. Refer to Body Control Module Replacement
in Body Control System.Did you complete the replacement? |
Go to Step 18 | - |
| 15 | Replace the high beam headlamp relay. 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 18 | - |
| 16 | Replace the low beam relay. 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 18 | - |
| 17 | Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal Switch Replacement
in Steering Wheel and Column. 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 |