CK5
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My wife's "American made" GMC Acadia...
- Thread starter Keitha
- Start date
No problem. I'm a gm fan to the end but I'm not shy to call things out when I see problems with the products.
Yup I got lucky with mine. Well guess its not lucky. Replacing the pump meant dropping the cradle a bit. There is no room to take the pump out without dropping the cradle.
So I got lucky with my choice for the wife's car, I was looking at 15 Acadia and then I found a great deal on a 15 Nissan rogue with 8k miles and got it.
It's simple enough and still has some nice stuff.
Did you figure out the problem with your's? I have not: I can disconnect the battery to reset the message on the dash. Then it runs fine for 10 - 15 miles before the service stabilytrack / service traction control message comes back on. The only service code that come on a scanner is P057c which is a brake pedal position sensor. I swapped in a new one ($13) and no improvement.
My wife can't drive it because once the service message comes on, it will miss and start bucking when under moderate load at anything over 35 MPH.
check your brake pads for wear.
The brake pedal position sensor is not just an on/off switch for the lights. Here's the definition from the Service Manual:
Circuit/System Description
The brake pedal position (BPP) sensor is part of the engine brake pedal override feature. The engine control module (ECM) continuously monitors the vehicle speed and the position of the brake pedal. These two main inputs, along with other ECM inputs are used to determine if the vehicle is decelerating at the proper speed and rate with the brake pedal applied. When the engine brake pedal override system is active, the ECM reduces engine torque to assist in reducing vehicle speed.
The BPP sensor is a six wire sensor, and is part of a dual brake position sensor. One BPP Sensor is used for the stop lamps and the other BPP Sensor is used for the engine brake pedal override feature. The BPP Sensor for engine brake pedal override communicates with the ECM. The ECM supplies a 5 V reference circuit, low reference circuit, and signal circuit to the BPP sensor. The BPP sensor sends a voltage signal to the ECM on the signal circuit. The voltage on the signal circuit will vary from a voltage greater than 0.25 V when the brake pedal is released to a voltage less than 4.75 V when the brake pedal is fully applied.
When they are replaced they are required to be relearned so it knows top and bottom. Unfortunately, it can only be done at the dealer since it has to be performed using the GDS2 application with a PC. Maybe a higher end scan tool like a Snapon or similar might have enough capability to perform the procedure too, but I can't vouch for that ability since we have the right stuff to start with.
Still, I can't say you will have fixed the problem with the sensor replacement. The code is specific f, or Brake Pedal Position Sensor Circuit Low Voltage. Meaning if the voltage value off the sensor drops below 0.25v the code is going to set. An open circuit between the sensor to the ECM will set the same code. So connections are critical. The reason why the car goes nuts when it sets is because the engine gets limited to 50% available torque and it starts brake torque management at 3.7psi of apply pressure.
You probably don't want to hear you need to take it to the dealer, lord knows I hear that stuff daily when I start quoting what repairs run these days. But it's the only way to go to truly diagnose the problem with the correct diagnostic equipment, which should prove out if the sensor is the problem or it's a circuit issue. It sucks, GM has basically made it so it has to come to the dealer for a good majority of the repairs as the aftermarket is locked out of some of the diagnostic capabilities. I don't agree with it, but it does force even other independent shops to bring cars they are working on to us to relearn something like this or upload current calibrations, ect. But, GM is not alone in this little game as all the manufacturers do this. I've invested a huge amount of money for the latest and greatest Snap-on diagnostic tool and pay out the ass quarterly to keep it up to date. However, even the mighty Snap-on organization can't get current model year information. That by some odd rule is limited to the manufacturer as they aren't required to make that available to outside companies. So while my guys can go pretty deep into a Ford, Chrysler, Toyota, Honda, Nissan, etc for diagnostics we can hit a wall where the part we need to install requires programming or being "learned" to the vehicle and we have to ship the ride out the dealer that is responsible for that brand.
As a DIY type guy I hate that the average guy that would hang out here (meaning more than capable in most repairs) is stuck with taking something to the dealer. It's also why I don't mind handing out info if asked. I get it all the time at work where some come in just looking for info on what is going on with their vehicle. I give them information if they can use it and if I see they are going to hit a wall that requires our help I'll let them know what the possible cost may be. Not all dealers are that easy with giving out info, but the way I see it that particular customer probably was going to fix it themselves so they might not be able to have us work on it. I'd rather gain trust by letting them have the info (some of which could be found on the web with some google-fu) and if they feel they got in too deep they might bring it back to me to fix. That's paid off many times over. Plus our we aren't alienating customers by withholding information by telling them they just have to bring it to us to fix or else.
ZooMad75 - Thanks for the great response. As much as I hate to hear it, I guess I have to bite the bullet and take the car in to the dealership. At least I can come in somewhat armed with the knowledge of what they should be doing.
