Both brake lights not working?

TRINITY58

MEMBER
2002 CHEVROLET EXPRESS
4.3L
6 CYL
2WD
AUTOMATIC
167,500 MILES

Good morning!

Having an issue with both brake lights not working on my newly acquired cargo van. Have checked both bulbs and they are good. The bulb sockets are clean. Running lights and turn signals are working, as well as the third brake light above the rear doors. If I put the brake light bulbs in "backwards", the brake filaments light up on both sides. No trailer lights are installed. Suspect brake light switch, but don't know which wires to check with voltmeter.

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,912 POSTS

The brake lights are controller by the white wire and if the nigh mount brake light is working this mean this part of the circuit is working, use a test light to see if you have power at the white wire when the brakes are depressed, here is a guide to help:

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

Here are the brake light wiring diagrams or you can see how the system works.

This guide can help as well:

https://www.2carpros.com/articles/brake-lights-not-working

Check out the images (below). Please let us know what happens.

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Friday, January 20th, 2023 AT 5:58 PM

TRINITY58

MEMBER
13 POSTS

Thank you for the diagrams Ken! Turns out there was a couple of issues. One was the contact bars inside both light bulb sockets were slightly bent downwards preventing a good connection with the bulbs. I straightened them up with a pick and had intermittent brake lights. Started to poke around with a dvm at the switch, and when I disconnected the electrical plug the whole brake light switch just fell apart. Looked like it was the original switch. The contacts inside the switch were burnt and one pair of contact points was just about wore out. Replaced the switch and everything works. Sorry for the delay in posting back, and thank you again for your advice. Hope this helps somebody else having a similar problem!

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Tuesday, April 16th, 2024 AT 9:38 PM

TRINITY58