High beams do not work and when you try to turn them on the low beams go out completely

JTETTING

MEMBER
2004 CHEVROLET TRAILBLAZER
V8
4WD
AUTOMATIC
190,000 MILES

Turned on high beams, looked dim, (like one was out) turned them off and then on again immediately, my regular headlights (low beams) went out as well as my running lights, so completely dark in front end of vehicle. Still had rear lights. Turned high beams off and low beams and running lights come back on.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

The first things I need you to check are fuses and the high beam relay. All of these are located in the under-hood fuse box.

If you look at the pic below, I highlighted the fuses and the relay. Note, there are two fuses. One for each headlamp is used.

When checking the fuses, not only check the fuse but also check for power to and from the fuse. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

As far as checking the relay, do this. If there is another one in the box having the same part number, switch them. If there isn't, here is a link that explains how to test a relay.

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

Please keep in mind (and don't laugh) it is possible that both high beam lamps may have burned out. You may not have noticed one was bad until both were bad.

Let me know what you find.

Joe

See pic below.

Image (Click to make bigger)