ABS/Stabilitrak issue

[mark_gober]

Hey everyone,

I'm new to this particular forum, but I post often in the Ford Windstar forum. I'm trying to help my sister out and I've ran into a problem I haven't seen before and hopefully someone can help me out.

She has a 2007 GMC Yukon with the 5.3l non flex fuel engine. (I know that this is a Chevrolet forum, but the Yukon forum seems to be particularly silent) Several months ago, she started saying that her "Service Stabilitrak" message would appear while she was driving. Further investigation showed me that her ABS sensor also came on at the same time.

I believe that she has an issue with her ABS system which is what's disengaging the stabilitrak system. Initially, I thought it was probably a bad wheel speed sensor, but as I was troubleshooting it today, I noticed something. If the car has been sitting for a few minutes and you start the car, the ABS light is out and the stabilitrak message is gone. If you slowly/lightly press the brake pedal, it will allow you to shift into gear and drive away. If, however, you firmly press the brake pedal when preparing to shift it into gear, the ABS light immediately comes on and the stabilitrak disengages. Mind you, at this point, the vehicle hasn't moved at all. To me, this rules out the wheel speed sensors and perhaps calls into question the pressure sensors or the ABS module itself.

I've never had any issues with brake pressure switches before, so I'm a little ignorant of how many there are and where they are located.

I look forward to any advice you folks might have as to how to proceed.

Sincerely,

Mark Gober

[777stickman]

Mark: The only way I know of to address this issue is to have the ABS system scanned for codes. Anything else is just speculation.

[j cAT]

Originally Posted by mark_gober

Hey everyone,

I'm new to this particular forum, but I post often in the Ford Windstar forum. I'm trying to help my sister out and I've ran into a problem I haven't seen before and hopefully someone can help me out.

She has a 2007 GMC Yukon with the 5.3l non flex fuel engine. (I know that this is a Chevrolet forum, but the Yukon forum seems to be particularly silent) Several months ago, she started saying that her "Service Stabilitrak" message would appear while she was driving. Further investigation showed me that her ABS sensor also came on at the same time.

I believe that she has an issue with her ABS system which is what's disengaging the stabilitrak system. Initially, I thought it was probably a bad wheel speed sensor, but as I was troubleshooting it today, I noticed something. If the car has been sitting for a few minutes and you start the car, the ABS light is out and the stabilitrak message is gone. If you slowly/lightly press the brake pedal, it will allow you to shift into gear and drive away. If, however, you firmly press the brake pedal when preparing to shift it into gear, the ABS light immediately comes on and the stabilitrak disengages. Mind you, at this point, the vehicle hasn't moved at all. To me, this rules out the wheel speed sensors and perhaps calls into question the pressure sensors or the ABS module itself.

I've never had any issues with brake pressure switches before, so I'm a little ignorant of how many there are and where they are located.

I look forward to any advice you folks might have as to how to proceed.

Sincerely,

Mark Gober

I never worked this system . what I believe is going on is the master cylinder pressure sensor and the brake signal input do not agree.

Master cylinder pressure sensor--The master cylinder pressure sensor is located within the BPMV. The master cylinder pressure sensor uses a 5-volt reference and generates an output signal proportionate to the hydraulic fluid pressure which is present in the front brake circuit at the master cylinder.

this could be the sensor or programing or wiring switch failures.

having the codes pulled would quickly point to the cause.

post back what fixed it.