brake apply sensor failing?

**Jesterville** · 09-27-2013

About a month ago I was driving along and I got warning to "Service Brake Apply Sensor" about a minute later I got warnings for traction control, antilock brakes and stability control. Worried about what was going on I pulled over and checked my brake lights, they were not working. I shut the car off and checked the brake light switch above the pedal and couldn't find anything obvious so I started the car back up and all the warnings were gone and the brake lights worked.

Fast forward to this morning on the way home from work and had a replay of all the warnings. I pulled over, shut off the car and restarted it and everything is good.

Can the brake light switch cause all this or is something more sinister going on?

**91parkave** · 09-27-2013

Originally Posted by Jesterville

About a month ago I was driving along and I got warning to "Service Brake Apply Sensor" about a minute later I got warnings for traction control, antilock brakes and stability control. Worried about what was going on I pulled over and checked my brake lights, they were not working. I shut the car off and checked the brake light switch above the pedal and couldn't find anything obvious so I started the car back up and all the warnings were gone and the brake lights worked.

Fast forward to this morning on the way home from work and had a replay of all the warnings. I pulled over, shut off the car and restarted it and everything is good.

Can the brake light switch cause all this or is something more sinister going on?

theres been a couple rare cases ive heard of this, some replaced the stoplight switch located right above the brake pedal and it still didnt fix the problem they ended up bringing the car in to the dealership and and the software on the PCM needed to be updated with the tech 2. ended up fixing the problem. free of charge too. might wana try that option.

**Jesterville** · 09-28-2013

Originally Posted by 91parkave

theres been a couple rare cases ive heard of this, some replaced the stoplight switch located right above the brake pedal and it still didnt fix the problem they ended up bringing the car in to the dealership and and the software on the PCM needed to be updated with the tech 2. ended up fixing the problem. free of charge too. might wana try that option.

I forgot about some symptoms in my first post......Two days before the first episode someone told me my brake lights would flicker when I hit bumps even though I wasn't touching the pedal.

If that new info doesn't change anything, I guess I'll change out the switch since it's cheap and easy.

Any idea what an update will cost @ a dealer? I never get lucky with the free stuff.

Thanks

**Jesterville** · 12-11-2013

Just wanted to give a quick update on my problem in case anyone else has the same issue. I replaced the switch in early November, by then it was happening 2-3 times a week, usually when hitting a bump. It went about a month with no issues then it did it again sitting at the bank drive through, first time when sitting still. I took the plug off the switch and adjusted the contacts to make sure they were making good contact, now I'm playing the waiting game again.

**Jesterville** · 01-29-2014

OK...Final Update....I hope.

The problem not only continued but got much worse, I actually was pulled over Christmas Eve for my brake lights being on constantly(nice guy, let me go with just a "be careful and get it looked at"), so I had Advance Auto check the codes and it came back with C0161 "ABS TCS brake switch circuit malfunction", which still left a ton of things it could be. I then took it to the dealership to be put on their machine. So $192 later I have a new Brake Pedal Position Sensor and a new inspection. Hopefully this will help someone else with similar symptoms.

**Jesterville** · 04-28-2014

The problem continues....

Everything seemed fine for a while, then at some point the flickering brake lights started again but only every once in a while. This time I also have had one instance of a Charging System Failure.

Back in the beginning when it originally started I remembered reading somewhere about the sensor on the negative battery cable being a possible suspect in a similar problem but I failed to ever really look at it. Well I did this time and this is what I found.....

I guess it wore away just from rubbing on top of the battery....

Until I can get the new sensor and put it on I wrapped it up in tape but I was thinking it may have been better to cover the opening with some sort of caulking.

**industrialfish** · 04-28-2014

What year is that? My 05 has the sensor down low near the batter tray in a way that prevents it from touching anything.

**Jesterville** · 04-30-2014

It's an 08, for now I've left in about the position you see it. It's not touching the battery or the brace above it but after hearing where yours is I may look to see if there is a better spot.

**ssn651** · 05-11-2014

I have a '07 GXP and I just received the same error messages on the DIC. I have not had a charging system error, but everything else related to brakes and stability control errors. Following your post, where should I start? Battery area or just head to the dealership? Buying and replacing the any sensors or switches a feasible DIY project or do I need to fork over cash to the dealership? Thoughts, Suggestions?
Thanks in Advance,

**Jesterville** · 05-11-2014

Well, checking that current sensor is free and easy. I filled the hole in mine with some black silicone and have been error free so far, my gas mileage has even improved.

If the sensor looks ok there were some other things that were pretty easy to check....make sure you don't have any light bulbs burned out (esp the 3rd brake light) and the connections to the bcm can get corroded, I pulled mine and cleaned them with contact cleaner then re-applied the dielectric grease. The brake light switch is also a possibility and that's not to hard to replace either, costs about $20 if I remember correctly.

On the more expensive/more difficult side I also read that a failing speed sensor or speed sensor wiring harness could cause similar problems.

If it's not one of the easy things you probably won't have much choice but to take it to the dealership and have them check it.. As 91parkave said it could also be a software issue.

Good Luck!

**ssn651** · 05-18-2014

First off, I need to say "Thanks" to Jesterville for getting this thread going. Next I want to share with those who find this thread what I went through to get this problem fixed. I even took photos That may help someone down the line. First off the "official" name of this part is Battery Current Sensor. (BCS) I did some research. GM made two different versions. A 5v version and a 10V version. You can turn the car on and put a meter across the middle and red wire to determine which voltage your car takes. This can be done with the connector unplugged. Rumor has it the voltage difference is based on the options your car has. The part number is: 13505369 for the 10v version. (What my GXP takes.) I looked at mine with Jesterville's photo in my head and guess what? Same damage. Same thing! Here is a photo of my Battery Current Sensor. 2007 GXP 2a.jpg

My next stop is a auto parts store. They have never heard of a BCS. I take them out to my car and show them. Still never heard of it and nothing, no part is listed on their computer. I next go to a brake specialist, (Ryhmes with "Makes-Fuss") and show them. They too have never seen this part or heard of it. Funny since this part caused my brake lights to fail, Traction control to fail, ABS to fail, and my Stabiltrak all to fail. Which left me forced to go to my local GM dealership. I pull into the service center and show them what I think my (and Jesterville's issue) is. They look at me like I am stupid and said THEY would take a look and TELL me what the problem is. Not the Grand Prix forums! An hour later they came back with the brake pedal switch failure theory and a $222 estimate! Of course I said "Gimme my car back." More research to be done. I found that the 10volts comes from the Brake Control Module. Which is why it would cause all these brake issues. I then disconnected the BCS and guess what? All my error messages went away and my brake lights came on. I then called the GM parts dept locally and spoke with the parts MGR. He had never heard of this part I was describing to him. But he did find it on his computer. I told him I needed the 10v version. Luckily he had that one in stock, sitting on his shelf. Only $21, All this hassle over $21? Here is the photo of the bag it came in. Part Bag1a.jpg Here is a photo of the new part. New Part a.jpg Problem Fixed! Thank You Jesterville, Thank You Grand Prix forums.

**HighOctaneRacing** · 05-18-2014

NICE! This is some good Info

**ssn651** · 05-18-2014

I also wanted to point out that this part is not uncommon in Grand Prix's. I also asked a coworker if I could look at his 2005 GP (Base). The negative is facing towards the firewall in his, while mine faces towards the grill. This Base version has the BCS sitting safely towards the bottom of the battery tray. I did not put a meter on it so I am unsure which voltage it takes. Again hope this helps.
Cheers,

**ssn651** · 05-19-2014

Thank You HighOctane Racing, I just wanted to pay it forward in case someone else has the same issue.
Cheers,

**91parkave** · 05-19-2014

Its also important to note that the BCS has a proper orientation as well. Pay attention when replacing the sensor. Great bit of info though, IMO id start another thread with the keywords for easy searching for future victims of this sensor

**Jesterville** · 05-19-2014

Glad to hear everything worked out for you!

FYI, I just looked at the part # on mine and it is the 5v one....10306471. So even among GXP's you have to check which one you need.

**ssn651** · 05-19-2014

Thanks Guys, I appreciate the support and feedback. Great to have the camaraderie.

Cheers,

**Stephinie** · 09-16-2014

hello i have a 2007 pontiac grand prix and i am having some what of a similar problem with brake lights staying on ,,,,well my heating core had went out so my husband and father in law had to install..but totally tore the dashboard and steering wheel took the brake and gas pedal completely out...got the heating core in but in the process of putting everything back together caused so many problems when it was done..at first our brake lights stayed on even when the brake was not being pushed...when we would push down on the gas pedal the car would not accelerate in (P) also the shifter was able to move to reverse, neutral, drive, without holding the brake pedal..so we took our car to a shop..where the mechanic got the car to run but still our parking brake lights wont come on when the headlights turn on..so therefore we cannot drive the car at night..and sometimes while we are driving our brake lights will stay on when we are not even pushing the brake...but we were told by a family friend that the problem is that the "brake positioning sensor" is loose therefore explains why our brake pedal is loose as well...but we just cant seem to find what the problem is..we just took our car to the shop today mechanic said everything came out good on his end...he thinks its an electrical wiring problem..because also we cannot read our stereo where it shows nothing it plays and works fine we just cant see anything on the screen...and a message came up on our car saying service park lamps...has anyone had this problem before...can someone please help me?????