Intermittent headlights issue

Hi.

When you pull the signal switch, you are getting high beam only. I suspect it is the switch itself, but there is a relay that can be checked first. It is under the hood in the fuse / relay box. I attached a pic below to help locate it (pic 1).

You have two choices to check it. First, see if there is another relay with the same part number and switch them to see if that makes a difference. Or, here is a link that shows how to test a relay. You will need a multi meter and a test light.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Here are a few links to help if you decide option two:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

If the relay is good, then my first suspect is the switch itself. Here are the directions for replacement. The attached pics correlate with the directions.

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2007 Chevy Truck TrailBlazer 4WD L6-4.2L
Removal and Replacement
Vehicle Sensors and Switches Sensors and Switches - Lighting and Horns Headlamp Switch Service and Repair Removal and Replacement
REMOVAL AND REPLACEMENT
HEADLAMP SWITCH REPLACEMENT

REMOVAL PROCEDURE
1. Open the left instrument panel (IP) access cover.

pic 2

2. Reach into the access hole and release the 4 retaining tabs located on the headlamp switch behind the IP.

pic 3

3. Remove the headlamp switch from the IP, through the IP access hole.
4. Disconnect the electrical connectors from the headlamp switch.
5. Remove the headlamp from the IP.

INSTALLATION PROCEDURE

pic 4

1. Position the headlamp switch near the access hole.
2. Connect the electrical connectors to the headlamp switch.

pic 5

3. Install the headlamp switch to the IP. Ensure that the retaining tabs are fully seated.
4. Install the left IP access cover.

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Let me know if this helps or if you have other questions.

Take care,
Joe

Hi,

Most likely, the switch is internally overheating and failing. Let me know if that takes care of the problem.

Take care,
Joe

Hi,

Glad to hear they are working again. Take care and have a good holiday season, Let us know if you have questions in the future.

Take care,
Joe