Why does my brake light interupt the right signal light when the head lights are on

1) Open trunk
2) Remove small round plastic access panel with a flat tip screw driver by prying open
3) Remove flat tip screw holding tail light assembly
4) Remove tail light assembly by pulling outward, careful not to break plastic guide/nub
5) Disconnect wiring connectors
6) Remove plastic housing access plate on back of tail light assembly by twisting/turning tabs until they click and then lift access plate from tail light assembly
7) When viewing the the bulbs, the turn signal bulb is the bottom left bulb
8) Install in reverse order, ensuring tail light seal seats properly during installation

check the light bulbs (filiments can break and touch the other filament in the bulb and backfeed other circuits) if they appear ok remove the non working bulbs and swap positions with the working bulbs and see if anything changes

Fast flashing dash signals mean there is a bulb issue-DEFINATELY!

Hello, Well there is not much more it could be unless you have a shorted wire or a burned fuse. I would normally think that the turn signal canceler was bad but the 3rd brake light will still work if that is bad so I would check all fuses and for bare or shorted wires.

You want to change the tail light bulb?

The process for replacing tail light bulbs is the same in all models. If you have a burnt-out tail light bulb, you may need to replace the brake light, the reverse light or the turn signal. The procedure to replace each of the bulbs is the same.

Instructions

1. Open the Hummer's rear swing gate. This will expose the edge of the vehicle's tail light assembly. You'll see two small Phillips head screws that hold the tail light assembly in place. Put on your gloves.


2. Remove the two screws from the tail light assembly. Pull the tail light out and inspect the back for two bulbs. The top bulb is the brake light and turn signal. The bottom bulb is the reverse bulb. Determine which bulb you need to replace.

3Rotate the bulb's socket counterclockwise to disconnect it. Unplug the bulb from its socket.

4Push the replacement bulb into its socket firmly. Insert the socket back into the tail light. Turn it clockwise to secure it in place.

5Place the tail light into its cradle. Hold it with one hand and replace the Phillips head screws with the other.

check the bulbs. The turn & Brake light works off the yellow wire for the left and a green wire for the right. The drive lights (tail lights) operate off of the brown wire. They use a double element bulb. Hope this helps. Also check your grounds.

Your earth is bonding properly. Make sure you have a good bond that is fixed either to your chassis, with all rust, sealent and other cotings are removed frois should dolve your problem.m the fixing. Th

Check the bulb. The problem has to be right there at the socket for the left rear. You do understand how the two filament bulbs work? The brake and turns use one filament, while the park lights use the smaller , less bright filament. And the bulb has two buttons on the bottom that touch two buttons in the socket. That is how the current is carried separate for the two lights.
It sounds like your bulb is wrong, or the socket itself is compromised.

If only your brake light in middle of rear window works then your other bulbs are bad. If brake lights all work in the back than bulbs are good. If you put turn signal on right or left and the bulbs light in front and back then you need to change multifunction light control box under dash. My understanding is it cost $600 new. So I would try used.

the tail light and brake lights are working from double contact bulbs. check the grounding, you dont have enough ground from one of the bulbs