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BOBBYSS, Master Technician
Category: Chevy
Satisfied Customers: 17368
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I have a 2008 Uplander. The speedometer cuts in and out.

Customer Question

Hi Dave, I have a 2008 Uplander. The speedometer cuts in and out. When the speedometer is working the van operates better but still jumps when changing gears. When the speedometer is not working it jumps into 2nd and 3rd gears and needs extra gas when getting on the highway. It also sometimes kicks out altogether and the engine will overspeed as it's in neutral. The engine has also just suddenly stopped in some occassions. When it stops it is usually going down an incline and with no gas applied. When no gas is applied it seems to be under speed at about 750 RPM. Any suggestions on what can be causing this?
Submitted: 1 year ago.
Category: Chevy
Expert:  BOBBYSS replied 1 year ago.

Hello, my name is***** for the question. Most of the time this is caused by a failing transmission speed sensor. If the computer sees no or an incorrect speed signal then the vehicle will act like this. It can also be a failure in the transmission control module but that is not as common. Please let me know if you need more help.

Customer: replied 1 year ago.
Hi Bobby, thanks for the reply. I had the speed sensor replaced and the transmission oil and filter changed but the problem didn't go away and became worse. The more frequently i use the van the more prone it is to slipping out of gear altogether and even having the engine shut off. Do you still think this could be the problem?Thanks,John
Expert:  BOBBYSS replied 1 year ago.

Does the speedometer still act up when this occurs? If it does then it may be a module problem. Did they happen to tell you how the fluid looked when it came out? If it was really dark or smelled burnt then the transmission may be failing.

Customer: replied 1 year ago.
They said the fluid was ok, a bit of metal shavings in the sensor when it was replaced. The speedometer most of the time just stays at zero or it jumps around. Once in a while the speedometer will read actual speed but it never stays that way for very long.
Expert:  BOBBYSS replied 1 year ago.

Does the transmission only act fine when the speedometer is acting fine?

Customer: replied 1 year ago.
The transmission acts ok with the speedometer working, It acts the worst when the speedometer is fluctuating. When the speedometer reads zero it is hit or miss - sometimes ok, sometimes jolting when changing
Expert:  BOBBYSS replied 1 year ago.

Thanks. Since the sensor was replaced and he signal is still acting up either there is a wiring issue from the sensor or the transmission control module is failing. Most of the time it is the module.

Customer: replied 1 year ago.
Ok thanks. I had read that there was an issue with the magnet in the transmission for these models not picking up enough metal and It was suggested to replace the magnet with a stronger magnet or two magnets? Do you think it's possible the speed sensor was the issue and became contaminated with metal again? I should have mentioned that the sensor was changed before the transmission fluid and filter were changed. I was thinking the sensor probably got blocked up with shavings again.
Expert:  BOBBYSS replied 1 year ago.

They should have checked the tone ring in the transmission for signs of metal when they changed the sensor. You may want to verify this with them.