The cruise and the brake lights in my '04 H2 are not working. The strange part is, the middle brake light is working though. The cruise started acting up a few weeks ago turning off by itself and being difficult to engage. Now it wont engage at all. Then yesterday someone yelled to me at a traffic light that I didn't have any brake lights except the middle one. Too coincidental not to be related.

I checked the fuses on both the engine panel and the dash panel, both good. I tried new bulbs, no go there. I checked voltage at the fuse panel, it's getting voltage when the brake pedal is pressed.

I dont know what else to check at this point. Anyone have any ideas?

Thanks in advance for any help.

 

A lot of GM's use a 2 wire lead off of the brake light switch. It could still be the switch, especially since it is turning off the cruise. Some even use a switch in the hydraulic system of the brakes for abs & third brake light, kinda like Ford does. Does this only happen when the tail lights / running lights are on? Do the turn signals work properly? You could have a wire shorted in back or a bulb socket shorted. Also check any trailer wiring harness, where it connects to the tail light wiring and where the trailer would plug in. It turn signals aren't right, the problem could go into a hazard switch. hth.

 

so i've replaced the blubs &the brake stop switch( brake pedal switch) i have taillights when the they are on. blinker works. reverse.. no brake or 3rd brake light... fuse is good.... any ideas?

thanks

 

 

No brake lights = No Cruise Control

The low resistance of the bulbs is monitored by BCU/ECU which is why replacement LED brake light bulbs can be problematic (I believe)

 

Who cares if it's an old thread? If it's relevant I am ok with it. I would look at the connector under the left rear of your H2. Maybe it corroded and making a bad connection. All the rear wiring harness passes through that connector.

 

From what you've said, if there's 12V on the bulbs it must be a ground distrubution issue, as you can see from the diagram the Center Stop Lamp is grounded differently which is probably why it works.

To prove a point manually ground the lamps to the chassis, they must come on if there's is 12v on them.

 

Turns out.. the put a diode on the brake pedal switch. Fried my inside fuse box.. removed diode, replaced fuse block. All good now