So, I spent a couple hours testing the brake lights just to find out that they only work with the key on

So trying to understand if this is how they are designed to work, only with key on or is there something wrong with my H2? I own 6 GM trucks (and 1 GM car) and this is the only one that requires the key on for the brake lights.

Does your H2 require the key on for the brake lights to come on?

Thanks Neal

 

My 06 works with key out. Only time i have seen a weird problem close to this. it was caused by the trailer plug. the trailers wiring caused a fuse to blow. or wiring within the 7-pin plug causing shorts.

 

thanks for the info
I wonder if its a 08/09 thing either way I'll keep looking
Going over the wiring diagrams there is a 12 volt power wire that gets power from the ignition, which is switched on the key but there is also a 12 volt reference wire that is hot all the time at the brake pedal switch. everything is controlled by the BCM, so without a good description on how the programing works I'm not sure what its supposed to do.
I'll take a look at the 06 diagrams and see if its different than the 08

Neal

 

08 BCMs are different than previous years. That is normal.

 

appreciate the info, thanks

I had looked over the earlier years and noticed the brake light signal does not go through the BCM like mine so figured the 08/09's worked as mine does

Neal