Cruise Control

[sdsuburb06]

1998 gmc sierra with 254k - engine and transmission have never been apart as I've had no issues. I did have the blinker/cruise switch replaced a few years ago as i had the constant blinker ticking sound and the switch was shot. Recently noticed when putting the truck in cruise control and hitting hills the vehicle refuses down shift - it will drop speed (say cruise is set at 70 and you hit a steep grade it will just drop down to 60 mph and once you reach level ground it will regain speed and settle at 70 mph). If cruise is off, truck will downshift as you'd expect when you hit a hill/steep grade. I do have an ABS light on, however cruise has worked appropriately with that light on for the last year. Hoping this is simply an issue with the cruise control itself, but never had this problem before, anyone else run into this issue and if so was it as easy as replacing the cruise control parts? Thank you, Matt.

 

[Eman85]

Scan the truck for codes, write all of them down then have them cleared and road test. Shouldn't have anything to do with cruise parts, they don't control transmission.