Transmission not shifting properly, speedometer fluctuating

Tiny
DAVID MIKEL
  • MEMBER
  • 2003 BUICK CENTURY
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 79,000 MILES
Transmission acts like it does not know which gear to stay in, shifting erratically and the speedometer fluctuates or shuts off altogether. I have replaced the speed sensor twice, car will run okay for ten to twenty miles then start the same problems. Are there any other sensors on the transmission that would cause this if faulty? Thanks
Tuesday, February 20th, 2018 AT 12:27 PM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,710 POSTS
Hello,

It sounds like you have a vehicle speed sensor that needs to be replaced. Here are diagrams to help you see what you are in for when doing the job.

Check out the diagrams (below).

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Wednesday, February 21st, 2018 AT 6:47 PM
Tiny
DAVID MIKEL
  • MEMBER
  • 1 POST
I have replaced it twice. The car will run well for about twenty miles then the problems start again.
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Thursday, February 22nd, 2018 AT 7:33 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,710 POSTS
Okay, lets run the codes to see what come up and go from there.

Here is a guide to help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please let us know what you find. We are interested to see what it is.

Cheers, Ken
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Thursday, February 22nd, 2018 AT 7:35 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,710 POSTS
Did you ever get the problem fixed?

Cheers, Ken
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Monday, March 12th, 2018 AT 7:03 PM
Tiny
FELICIA CAMPOS
  • MEMBER
  • 1 POST
I know this was a few years ago and I don't even know if you will get my message, but did you ever find out what was going on with that Buick? I have the same exact car in the same problems just started happening to mine. So, I figured maybe you would have the answers. Please let me know I really appreciate it.
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Friday, October 29th, 2021 AT 4:46 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Unfortunately, it is unlikely that they will respond however, I am sure we can help you with your issue and if we can reach a resolution then you will help the next person that has this issue.

Would you mind getting a new post started with your vehicle specifics and what your issue is. Plus, any parts that you have replaced and one of us will jump on it.

https://www.2carpros.com/questions/new

Thanks
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Tuesday, November 2nd, 2021 AT 1:42 PM

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