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Hello, I am new to the site and hoping to get some advice or help

I have a 2008 Chevy impala LT 3.5 and in wet weather the speedometer needle will bounce around and occasionally the needle will spike all the way up and a “speed limited to 107 mph” warning will display on the dic, this will cause the engine to stall out and require me to restart the vehicle.

This only happens when it’s wet out and seems to only happen at low speeds while coasting or braking, occasionally when I am stopped and take my foot of the brake to accelerate the needle would jump also.

I am wondering if it could be a faulty vehicle speed sensor or if there is anything else that could cause this issue. any feedback would be greatly appreciated! Thanks! :eek:k3:
 

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Hello, I am new to the site and hoping to get some advice or help

I have a 2008 Chevy impala LT 3.5 and in wet weather the speedometer needle will bounce around and occasionally the needle will spike all the way up and a “speed limited to 107 mph” warning will display on the dic, this will cause the engine to stall out and require me to restart the vehicle.

This only happens when it’s wet out and seems to only happen at low speeds while coasting or braking, occasionally when I am stopped and take my foot of the brake to accelerate the needle would jump also.

I am wondering if it could be a faulty vehicle speed sensor or if there is anything else that could cause this issue. any feedback would be greatly appreciated! Thanks! :eek:k3:

I would bet it is the vehicle speed sensor (VSS). Buy a new ACDelco part - they are not very expensive.

If I remember correctly, the VSS attaches to the passenger side of the transmission. There is one bolt holding it and one electrical connector. It is near the right front axle shaft - where it enters the transmission.

When you remove the sensor, ensure the o-ring that is around the VSS body comes out. The new VSS should have a new o-ring attached. You will have to remove the right front wheel and tire, and the inner plastic fender liner to access the sensor.
 

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Just an update. Had the vss replaced and that has not solved the issue. Anybody have any ideas on what else could be the problem?
 

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Hi. I'm having the same exact issue. I too have replaced the VSS (output) and it did not fix the issue. Did you ever fix this problem?
 

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I found a solution!!!

I was having this exact same problem. One thing that I noticed, in addition to the speedometer doing acrobatics when the engine was cold, was that my speedometer would not register anything on acceleration until I got up to 15mph or so, then it would try to shift into 2nd gear a little too late. I tried replacing both the output speed sensor and the input speed sensor (inside the transmission) with no success. The fix was found when I was replacing the output speed sensor's wiring harness. One of the speed sensor wires had rubbed itself bare on the oil pan as the wire bundle went under the engine and must have been shorting out. After replacing the wiring harness (which spliced into the old wires just past where the bare spot was) with Dorman 645-782 (AC Delco #: PT2437), my speedometer issues are completely gone!
 

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The fix was found when I was replacing the output speed sensor's wiring harness. One of the speed sensor wires had rubbed itself bare on the oil pan as the wire bundle went under the engine and must have been shorting out. After replacing the wiring harness
I wanted to point out that although different hardware, the ABS wire had also worn through the casing from the module to the wheel. A piece of Styrofoam tubing solved my issue for a year now and my ABS has not kicked on turning the car anymore. It seems this problem is repetitive and reoccurring and I would suspect the harness all the same.
 

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I have a 2011 I just purchased for my son. My speedo jumps when in Drive, only when stopped and intermittently stalls. Highway driving is fine. I replaced vss and still same. No codes being thrown. Just wanted to see if anyone else has had this similar issue. I will inspect wiring when I have a chance.
 

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I found a solution!!!

I was having this exact same problem. One thing that I noticed, in addition to the speedometer doing acrobatics when the engine was cold, was that my speedometer would not register anything on acceleration until I got up to 15mph or so, then it would try to shift into 2nd gear a little too late. I tried replacing both the output speed sensor and the input speed sensor (inside the transmission) with no success. The fix was found when I was replacing the output speed sensor's wiring harness. One of the speed sensor wires had rubbed itself bare on the oil pan as the wire bundle went under the engine and must have been shorting out. After replacing the wiring harness (which spliced into the old wires just past where the bare spot was) with Dorman 645-782 (AC Delco #: PT2437), my speedometer issues are completely gone!
Thanks for the tip! I too was having problems with my speedometer registering the 107 MPH and stalling when it came to a stop or as you were accelerating from a stop. I had replaced my Vehicle Speed Output Sensor and that solved the problem for about 2 weeks then it started up again. From your suggestion I went back under the car as I remembered I never put that tab back over the bolt that sticks which secures the VSS on. It looked like things were a little twisted and I put that tab back on and secured another area that was hanging down. I feel like this loosened the connector some. Took for a test drive and all seems well! We will see how long it lasts but definitely know it is the connector or wires that were causing the problem.
 
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