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Discussion Starter #1 (Edited by Moderator)
I posted this in the general discussion but thought I would post here also. I have an 05 Chevy Malibu LS with a 3.5l engine. I was driving home from the long weekend, which is a 2.5 hour drive. When slowing down or coming to a stop after about an hour of highway driving, the car goes into limp mode, I'm guessing. I press on the accelerator and nothing happens, don't go anywhere and the engine does not accelerate. Most of the engine will shut off while the lights stay on. Sometimes the traction light will come on, not always. The engine light does not come on at all. Plus I just put this transmission in 1 month ago. (It was used, not new or rebuilt) The reason for this was the old one was doing almost the exact same thing less the traction light coming on. I was told the transmission needed replacing. Please help. I bought this used 3 or 4 months ago and have had nothing but problems.
 

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Hello and welcome @sawstihl.

I cleaned up your duplicate discussion to help focus any assistance you receive in one place. Plus this post has a bit more important info (I also edited your post to clean up some typos that could lead to confusion). With everything you have provided I am hopeful you receive some useful advice.

Good luck!
 

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Discussion Starter #3 (Edited by Moderator)
Adding a few things since my original post....a few times the engine revved up by itself, I did not touch the accelerator. It revved to about 2000 to 2500 rpm's. Drove to work this morning, about 20 min drive, with no issues. Thanks
 

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The most likely cause is a front wheel bearing assembly. GM has been having a huge problem with them for many years. Due to the design, the wheel speed sensors don't generate much of a signal to start with, and in as little as 15,000 miles the wheel bearing can develop normal play that would go unnoticed on any other car brand but on yours that causes the signal to drop so low that the computer can't read it. That makes it look like that wheel is going slower than the others so the traction control kicks in to slow the other one down that it thinks is spinning.

On any other brand you replace only the wheel speed sensor when it fails. GM likes to build their cars with large assemblies to cut down on labor cost and time on the assembly line. That means you get to buy the wheel speed sensor AND the wheel bearing whenever you need either one of them.

To verify the bearing / sensor is the cause of the problem, your mechanic will perform a test drive with a scanner that lets him view live data. He will be able to see the speeds being reported by all the wheel speed sensors when the false activation occurs.
 

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Adding a few things since my original post....a few times the engine revved up by itself, I did not touch the accelerator. It revved to about 2000 to 2500 rpm's. Drove to work this morning, about 20 min drive, with no issues. Thanks
If it was the wheel speed sensor, would it not act up no matter how long you drive?
 

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The most likely cause is a front wheel bearing assembly. GM has been having a huge problem with them for many years. Due to the design, the wheel speed sensors don't generate much of a signal to start with, and in as little as 15,000 miles the wheel bearing can develop normal play that would go unnoticed on any other car brand but on yours that causes the signal to drop so low that the computer can't read it. That makes it look like that wheel is going slower than the others so the traction control kicks in to slow the other one down that it thinks is spinning.

On any other brand you replace only the wheel speed sensor when it fails. GM likes to build their cars with large assemblies to cut down on labor cost and time on the assembly line. That means you get to buy the wheel speed sensor AND the wheel bearing whenever you need either one of them.

To verify the bearing / sensor is the cause of the problem, your mechanic will perform a test drive with a scanner that lets him view live data. He will be able to see the speeds being reported by all the wheel speed sensors when the false activation occurs.
I'm scratching my head on that diagnosis!

Limp mode is when the computer determines that the engine needs immediate service and will barely propel the car at more than pedestrian speeds.

When the TC or ESC is incapacitated as a result of any part failure, it does not put the car into limp mode.

I think you would do us all a considerable service if you could explain how limp mode and VSS failure are related. As of now, I don't see it.
 

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I think that the throttle actuator needs to be serviced. DrivenDaily is correct the TC or ESC will be diabled as a result of part failure.

"As the engine operates large volumes of air are processed which leaves behind deposits that can hinder the actuators operation and deflect air flow in an undesirable manner causing the engine to stumble (hesitate), hard steering and limp mode conditions. When these deposits called coking become sever enough the car's computer will detect a correlation mismatch and reduce the power of the engine as a safety precaution."

This would also explain the rough idle and the random jumps in rpm. Does it ever die at idle?

Here's the website I got the quote from. It will also walk you through the process of service.
https://www.2carpros.com/articles/throttle-actuator-service
 
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