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Carguyjosh, ASE Certified Technician
Category: Pontiac
Satisfied Customers: 2172
Experience:  ASE certified, 16yrs in automotive field
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I have a 2004 Pontiac Montana and the traction active light

Resolved Question:

I have a 2004 Pontiac Montana and the traction active light comes on. hile it is on, it sounds like something is grinding. Some times when I press the brake pedal to stop, it sounds like the front brakes are metal to metal.
I have had brakes put on all four wheels. Can you tell me what the problem is?
I had the shop to check it out and they run a diagnostic on it and it shows that there is no code.
Submitted: 7 years ago.
Category: Pontiac
Expert:  Carguyjosh replied 7 years ago.

When you are coming to a stop, Do you sometimes hear the grinding sound and feel a vibration in the brake pedal?

Also, is there an ABS light that comes on?


Please let me know and we'll see what we can figure out....


Thanks, Carguyjosh

Customer: replied 7 years ago.

I do feel a vibration . I feels as if the brake pedal goes in further than usual.

The ABS light does not come on.

Expert:  Carguyjosh replied 7 years ago.

What is occurring is that a front wheel speed sensor is failing. I'll give you the just of how the system works and why you are having the problems that you are.


The anti-lock brake system and the traction control system both function off of the 4 wheel speed sensors. 1 is located at each of the 4 wheels.


As your car is moving, the anti-lock computer is monitoring the speed of each of the 4 wheels. When you are first taking off, if one of the front wheel speed sensors is reading 0mph and the other is reading the actual speed,(say 5mph) the computer thinks that you are stuck and therefore activates the traction control system.


The same holds true for the anti-lock brakes.

As you are coming to your final stop, if one of the speed sensors drops to zero, the computer believes that you are skidding and activates the anti-lock brakes.


You must be in the beginning phases of a sensor failure. In time, your computer will realize that there is a sensor malfunction and turn the ABS light on.

The reason that there is no code is due to the fact that the computer has not yet recorded a failure.


For the diagnosis of the problem. You will need a shop that has a lab scope capable of monitoring the front wheel speed sensors together to see which on is causing the failure.

Its not as difficult as it may sound, I work with these types of problems quite often...


Please let me know if you have any further questions...


Thanks, Carguyjosh

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