1999 Denali Transmission Problem

[Mr.890]

When driving my 1999 Denali for an extended period of time, it begins shifting very hard, then eventually the SES light comes on.

When I shut the truck off, the SES light stays on, but it shifts fine until I make another extended trip, say 30 miles or longer.

I've had the transmission rebuilt, what is the deal?

Anyone help?

[MRiad]

Originally Posted by Mr.890

When driving my 1999 Denali for an extended period of time, it begins shifting very hard, then eventually the SES light comes on.

When I shut the truck off, the SES light stays on, but it shifts fine until I make another extended trip, say 30 miles or longer.

I've had the transmission rebuilt, what is the deal?

Anyone help?

I have the same problem with my 1996 Yukon and I used a OBDII code reader and gave me P1886 which is "Transaxle Shift, Timing Solenoid Performance". Now I think a Transmission shop would know how to fix it.
Usually transmission solenoids' are not expensive.
Good luck.

[Eggert]

Hi,
I'll translate the codes, if you post them.
Is the shop willing to fix this under warrantee?

Take care, Eggert