Pontiac Grand Prix Traction Light On

Question: Yes my car traction light is on and sometimes it brakes on its own while im driving and when it does that it says stability control on or active also it says service traction system.
 Mechanic: Model and year vehicle?

2007 grand prix gxp 5.3 v8.
 Ok. Most traction control problems are caused by an antilock brake problem. You would need to get the antilock brake computer scanned for codes. A common problem is a bad wheel speed sensor.

Would that cause the car to brake while I am driving?
 It can, but not usually. The computer gets confused and thinks one of the wheels is braking, so it tries to compensate.

So the wheel sensor could be confusing the computer basically?
 Yes.

How do I diagnose which wheel sensor it is?
 You would need to get the computer scanned for codes. It will tell you which one is having a problem. Or, you could use an ohm meter to test each one.

I have it at a shop now and the only code he got was a steering position sensor.
 A steering position sensor could cause the traction system light, but would not cause the car to brake itself. Unless the feeling you are getting seems like it ios braking, but really is not.

So most likely its speed sensors because it definatly brakes on its own while im driving and it brakes hard and it says stability control active everytime it brakes on its own.
 I would get that steering sensor replaced first, clear codes and re-check.

 

I also have a couple trans codes.
 What are they?

p0826 and p0842.
 Those are for a pressure control circuit, but should not be giving you the problem you have. It may be a result of the problem you are having.

That's a different problem it shifts funny sometimes and sometimes the car drives excellent.
 Yes.

So that's inside the transmission? Cuz when i start the can and try to pull right off it jerks and drags but when it warms up it drives perfect.
 Yes, sounds like the pressure control solenoid.

I love but hate this damn car. Last but not least i have a po420 code i been changed the cat i thinkin maybe the o2 sensors.
 How much did the new catalyitc converter cost?

$300 with install.
 I have seen many inexpensive converter still cause the P0442. Beleive it or not, $300 installed is pretty cheap.

No p0420 not p0442 but after i replaced the cat the code still came back so im guessing its the o2 sensors.
 Sorry typo- meant P0420. Have only seen one time a post converter O2 sensor cause the p0420. Always the converter. FYI- for a p0420 code to be run and pass in the computer memory, it must be driven on the x=press way for 15 minutes, then sit at idle for another 5 minutes, or the code can return. Also, a cheap converter that is not cleaning up the exhaust will give the P0420 right away, making you think that the converter was not the problem to begin with.Cheap converters are just that, cheap, and do not have the emissions cleaning capability as a quality converter- consider the factory cat. is over $600 for part itself.

I also changed to a magnaflow high flow cat is that good?
 Again, very incexpensive. Have not used that brand myself. Get the steering sensor fixed first, that is most important. Have all computer codes cleared, and go from there.

Will a steering position sensor off of a grand prix that is not a gxp work on my car im taking it off of a regular 2005 Pontiac grand prix?
 Hard to say. There will be a part number on it, make sure they match. Part # is either 10336934, or 19149528.