Hazards lights flash when braking. [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Hazards lights flash when braking.

04-13-2011, 06:11 PM
I have an 02 trailblazer and when I push down on the brake the blinker and marker lights flash on and off. I believe this is an indicator of a light out however I have been over every light multiple times and all lights are working. Anyone know what the problem could be?

the roadie
04-13-2011, 06:52 PM
Much more likely to be a short in the wiring or the tail light PC board. Except for fast flashing, the trailvoy platform doesn't have any indicators of dead lights except for ..... the dead lights.

Could be a failure of the flasher module, but I'd be removing the tail lights first for a good inspection.

Do you have a meter to help you in your quest?

04-13-2011, 08:00 PM
To add to what the roadie is saying (your now dealing with the Bill and Ray team :yes: ), the flasher lights and the brake lights are separate lamps within the taillight housings (as you know); however, most trailers share bulbs with the brake and turn signals (ie: one bulb filament is used for both brake and turn, per trailer side).

The flasher unit combines the turn and brake signals into a shared lead going to the trailer through the connector on the rear of the trailer.

If the rear circuit boards are ok, check the trailer connector for dirt/shorts before you run out to buy a new flasher (btw, I'm betting on the flasher Bill :raspberry ).

04-13-2011, 08:07 PM
Check the resource tabs and see if your year and model qualify for the recall.

You can go to chevy.com as well and make an owners account and input you VIN. After you make an account it'll show you if you have any outstanding recalls.

I had an issue with mine they would start flashing for no reason or they would just freeze. I recently had the recall taken care of and they replaced the flasher module and the tail light circuit board.

Good Luck :thumbsup: I hope you fall under that recall, tracking a short is never fun.

04-14-2011, 09:55 AM
I had a trailer plug adapter go bad. It converts car side to 4 flat plug. It caused all sorts of problems with blinkers and brakes. Don't know if you have one or not just throwing out what my issue. Also you can try unhooking both tailights and see if the problem goes away. If not sounds like the flasher module may be taking a dump. Good Luck!

04-14-2011, 10:15 AM
A fellow Tb of mine did have this problem, and he installed a new Relay and fixed his issue, so you should just check everything, bulbs, receptacle, wires, box, and relay.

the roadie
04-14-2011, 11:31 AM
...he installed a new Relay ...Specifically WHICH relay? There are many, and I don't see a single one causing this set of symptoms. Unless you mean the flasher module, which is a simpler relay on many other vehicles.