Thread: urgent help.. break lights work but only when I make a complete stop

Hello I have a 2006 grand Prix I recently bought from a guy.. Ive noticed on the dash it says service break apply sensor... My break lights come on only when i make a complete stop. They do not give off warning that im slowing down until im a 0 mph.. In the last month I have spent well over 700$ trying to fix the problem.. I've replaced the
Brake switch-
Brake pedal position sensor-
Body control module-
Checking all wires for short
Another body control module
Plus labor..
I'm so tired of getting the run around I just need some real advice that will help my problem.
Thank you

http://www.grandprixforums.net/threa...sensor-failing

I like to start out learning about the system.

Stop Lamps

The turn signal lamps are also used as stop lamps. The STOP/TURN/HAZARD fuse in the instrument panel (I/P) fuse block supplies battery positive voltage to the body control module (BCM) for the stop lamps.
A 10-volt reference signal and a low reference signal is applied from the BCM to the brake pedal position (BPP) sensor. When the brake pedal is applied, the BPP sensor applies a signal to the BPP sensor signal circuit to the BCM. The BCM then applies battery positive voltage to the LR and RR stop/tail/turn lamps through the LR and RR stop/turn lamps supply voltage circuit. The BCM also supplies a battery positive voltage to the CHMSL through the stop lamp supply voltage circuit. The ground for the LR stop/tail/turn lamp is supplied from G301 The ground for the RR stop/tail/turn lamp and for the CHMSL is supplied from G302.

There's clearly more info in what TurboSBC linked you to that isn't really explained in the above. Some good stuff there, it seems that likely either the reference is bad or you need to have the switch reprogrammed/relearned.