- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Kevin , this is a very complex way of stoplamp control , I will post GM service Description and Operation of how they work an let you deside if you want to tackle this ! Do the center high mount brake lights work ?
The brake pedal position sensor is a resistive device used to sense the action of the driver's application of the brake pedal. The brake pedal position sensor provides an analog signal that will increase as the brake pedal is pressed.
The brake pedal position sensor receives both a 5-volt reference voltage and a low reference signal from the electronic brake control module (EBCM). When the brake pedal is pressed, a variable signal is applied from the brake pedal position sensor to the EBCM through the brake sensor signal circuit. The fuse block left rear supplies battery positive voltage to the bass relay switch through the BASS fuse. One side of the bass relay coil is permanently grounded at G402. The EBCM supplies voltage to the bass relay coil upon receiving the signal from the brake pedal position sensor. The switch contacts of the bas relay close and battery positive voltage is applied through the bas relay switch to the center high mounted stop lamp (CHMSL), and to the turn signal/hazard flasher module through the stop lamp switch signal circuit. The ground for the CHMSL is applied from G402. The turn signal/hazard flasher module then supplies voltage to the left and right stop lamps in the tail lamp assemblies that have ground at G401 and G402. For export vehicles the stop lamps receive battery positive voltage directly from the bass relay.
There could be a code stored in the EBCM - electronic brake control module - DTC B3903 Stop Lamp Relay Circuit
DTC C0278 Brake Pedal Position Sensor Not Calibrated
there are several other codes that pertane to the brake lights . you could try Replaceing the bas relay !
Fuse Block - Left Rear
In the passenger compartment, under the left side of the rear seat at carpet.
Check the brake light switch (location pedal) unplug the switch & bridge the wires & if the brake lights come on the switch is faulty. all you are doing by bridgeing the wires is bypassing the switch. What is SLS?
The brake switch will stop all current to the brake lights. As soon as the brake pedal moves just off of its fully up position, the switch makes contact and passes current on to the brake lights. You can operate it by hand to check if everything is right. izzit adjustable? The switch is the last thing in the path to the brake bulbs, so it has to work right, right off the brake pedal!
brake light dont have relay only fuse brakes are hot at all times on gms. in goes from fuse to brake pedal switch to hazard turn signal switch then to brake lights. ck fuse if good go to pedal switch if good go to turn /hazard switch the turn signal hazard brake all use same wire to lamps.
Did you check the fuse for the stop lamps ? This is cab fuse panel F2 ( where the turn signal is fuse F13 ).
When you tested the old or new BPP ( Brake PEdal Position ) Switch, did you have power on the side from the fuse ( this is the light green w/ red stripe wire ) ? When you pressed the brake pedal down, did you have power on the side towards the brake lamps ( this is the Light green wire ) ?
There is a short somewhere between the switch and the brake lights. I would inspect the light holders very carefully. This would be the first place that corrosion could start because of water and weather. After that you would have to follow and inspect the wiring. Has it been pinched, crushed, kinked or damaged?
Have you tried to reconnect one light and push pedal? Is problem common to both?
Being an electrical tech I would measure the resistance on the wiring to ground, should read infinity (no contact). Good luck!
WHICH GLOBES (BULBS)? I presume Brake Lights? The circuit is a DIRECT CONNECTION at the brake SWITCH (brake pedal arm). If all your fuses are good, then I'd begin to suspect the brake lamp switch is defective.
brake switch on the pedal bad.bad relay. do you have a second fuse box if so check it. look at the wiring see if it is frayed or chafed check the connections.check all the fuses not just the ones labeled brakes.switch the relay with one that you know is good like turn signal and see if the turn signal works then check brakes.use a 12 volt test light check the brake switch and probe the wires. hope this helped if not write back and i'll give you more ideas.
Does the 3rd brake lamp illuminate? If so then your problem is multifunction switch.If it doesn't do the following checks.
Check for power to and thru the brake lamp switch itself.If you do not have power to the switch check fuse no. 10(20 amp) in the interior fuse panel.If you have power to the switch then depress brake pedal and make sure you have power thru the switch.If this is ok the check Fuse 22(20amp) with brake applied..