Maybe a stuck relay or bad headlamp switch ! You may have a DTC - diagnostic trouble code stored in the BCM - body control module ! These codes do not turn on the check engine light ! There could be a yellow wrench symbol on the instrument cluster or a service vehicle soon light or a message in the message center if yours has one ! You would need a professional grade scan tool to check for codes in the BCM !
DTC B2578 Headlamp Relay Control Circuit High.
DTC B2577 Headlamp Control Circuit Low.
DTC B2575 Headlamp Control Circuit !
If no codes were found you would need to do some tests ,such as these .
If no codes
Headlamp Low or High Beams Always On test
2
- Ensure that the ambient light sensor is receiving enough light to simulate daylight conditions.
- Place the headlamp switch in the OFF position.
- Turn ON the ignition, with the engine OFF.
- Turn OFF the ignition.
Do the headlamps operate normally?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3
3
Are the headlamps ON with the ignition key ON, and then turn OFF when the ignition key is placed in the OFF position?
Go to Step 4 yes
Go to Step 5 no
4
Test the headlamp relay control circuit of the body control module (BCM) 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 15 yes
Go to Step 10 no
5
Disconnect the headlamp relay. Refer to Relay Replacement in Wiring Systems.
Do the headlamps turn OFF?
Go to Step 8 yes
Go to Step 6 no
6
Disconnect the headlamp switch connector.
Do the headlamps turn OFF?
Go to Step 7 yes
Go to Step 11 no
7
Test the headlamp relay output circuit of the headlamp relay 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 15
Go to Step 9
8
Inspect for poor connections at the harness connector of the headlamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems?
Did you find and correct the condition?
Go to Step 15
Go to Step 12
9
Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 15
Go to Step 13
10
Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 15
Go to Step 14
This mite be a problem you would want to leave to a ASE certified Technician who has the tools an knowledge ! Probably could be fix in less then an hour !
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