1998 GMC Jimmy Transmission shifting at constant speed

LEE BRESMON

MEMBER
1998 GMC JIMMY
6 CYL
4WD
AUTOMATIC
118,000 MILES

My 1998 GMC Jimmy 118000 miles shifts gears while driving at a constant speed. 45-55 mph is the range this occurs - the frequency is every few seconds. I had the transmission flushed 10000 miles ago and the problem went away - now it is back. Any idea what the problem is? Have it flushed again?

3 Replies

FACTORYJACK

MECHANIC
4,159 POSTS

Is it a continuous upshift/downshift pattern while driving at a constant speed? Is there any check engine light associated when it acts up. At first glance, I would lean toward an issue with the transmission valve body, especially since the service changed it for a while. Has there ever been any water in the fluid, is the fill tube, or indicator stick rusty?

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Thursday, February 11th, 2010 AT 12:03 AM

LEE BRESMON

MEMBER
2 POSTS

Yes, it is a continuous upshift/downshift pattern while driving at a constant speed. The check engine light does not come on when this eratic shifting occurs. Would you suggest trying to have it flushed again? Is this something I should be dealing with a transmission shop? Thank you

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Thursday, February 11th, 2010 AT 2:29 AM

FACTORYJACK

MECHANIC
4,159 POSTS

Flushing again might just be flushing away money, if it don't work. When it was serviced 10k miles ago was the pan removed and filter changed? It might be in your best interest to get an opinion on it, someone that can experience it.

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Friday, February 12th, 2010 AT 12:03 AM