Brake lights always on - incl CHMSL
18 Silverado bought to my shop from collision center. Repaired light hit RF corner. No DTC's . Brake lamps..all including center mounted lamp on all the time . I relearned the pedal through the BCM. My scanner shows no brake pedal applied at rest, with pressure on pedal I read “pedal applied”. Learn is successful. I have brake pedal sensor learned release at 1..06 and 1.06v and 42%. At rest the brake pedal sensor shows 1.17 volts . I see the BCM is commanding the lamps on, I just don't see what input it is using to command them on. I can command them off and each lamp will turn off. Shop installed new sensor due to this issue. There are aftermarket fog lamps installed on the oem circuit as an FYI. I doubt is needs a new BCM but that is where I am now. Any ideas? . Help or ideas appreciated.
Use the “KISS” method. Follow SI. Don't get fancy. A system that was working before an accident should be inspected for the obvious wiring and connection concerns, that often occur during collision repairs. Wiring concerns? Incorrect bulbs? Fuses not blown and in correct locations in fuse blocks? Grounds? - Many times, fuses in the wrong locations can cause weird and wornderful concerns! If…
I agree . Have checked all the fuses prior to my post. Trying to figure out what could cause this in the area it was repaired. I can manually move the brake sensor and can get the brake lights to blink on/off but can't hold it there to keep them off. That is why I was asking about the brake sensor calibration procedure. There still would no be a reason for it to work prior then after accident…
What is the procedure to calibrate the brake sensor. FSM says to follow direction on the scan tool. My Autel is not giving me step by step. I do have access to SPS. When I toggle “learn” (from BCM ) it says completed but no steps were pointed out. I thought it was brake pedal travel top to bottom 8 times with a 2 second interval?
Don't touch the brake pedal during the postion sensor learn or it will fail. Both the BCM and ECM use the info, also HPCM on hybrids Basic steps using GDS 2 below. Your tool may differ - Park, KOEO - Clear any DTCs - BCM > Config/Reset functions menu > Brake Pedal Position Sensor Learn & follow instructions - ECM/HPCM > Learn > BPPS Sensor Learn & follow instructions
I know not to touch brake pedal, also verified it passed and had “no” for moving brake pedal during calibration. Cleared the codes KOEO but the was NO instructions that followed. I hit “learn” and it goes a few seconds and it says succeeded . The instruction for sequence of applying brake pedal on/off etc does not come up.?
Sorry, I cannot confirm. I have no idea what control functions Autel may have available. I would have to drive to work and dig out a snow covered truck and select the learn procedure using GDS 2 to see the steps. I'm on vacation until January 10th and staying warm! Don't forget to check those G102 grounds at the R/F frame by the body mount for headlamps and fog lamps.
Hi Chris, Even a wrong bulb can cause issues like this. Check them. Also verify no hidden body man wiring repairs. I've seen some interesting things happen, especially with body shops. They are only concerned that it looks good, not that everything works…. They push all kinds of problems off on techs.
I will call it a day and pull the panels off the front tomorrow and go from there. Thanks. If any one DOES know the sequence to relearn the brake sensor please post that.
Calibration is a scan tool configuration/reset function. See SI Doc # 2172958 or equivalent, in an alternate information system for the steps. Look for sensor replacement. Calibration is the last step.
Sensor replacement in SI says perform steps as tool indicates. It indicated no steps, but other models have been a pedal press and release slowly for 8 times with a 2 second interval. I am adding more information below…
“They are only concerned that it looks good, not that everything works” and their evil cousins, the style and design engineers!
Just a thought, predictive braking systems have the authority to turn on the brake lights when automatically braking (distance cruise, semi-autonomous avoidance). Maybe the EBCM is commanding it on.
So, as I posted earlier I was calling it a night. Went to move the truck inside I did a light check against the building (it is dark here) . I do a flash to pass and the high beam won't stay on (with light switch off) . With lamps on I can get low and high beams to work as they should but I get a “flicker” that is not normal when switching from high and low. So I turn the fog light (driving…
Sounds like you're getting closer. Ground for the right headlamp is G102 on the frame, near the front mount and just happens to be the same location for the right front fog lamp. Those HID lamps are pretty simple with the BCM controlling the shutter to allow all light to pass for high beam. Pushing the multi-function lever towards the dash switches to high beam. Pulling the lever back from…
Thanks Martin! I have a plan for tomorrow. They must have installed those aftermarket lamps on the wrong circuit : reversed polarity etc.
Hi Tony. Good thought, but the truck doesn't appear to have the Integrated Brake Assist option UHY.
as everyone said, start with unplugging everything that was replaced at the collision center. See if problem is still there. I doubt it will be.
Yadda, Yadda, Yadda…. disconnected all aftermarket items and wiring… brake lamps still on all the time…. Replaced BCM, problem fixed. (Although I had a heck of a time setting the new BCM up. First time I programmed on Techline since the rollover of SPS in October).