I know this is not a 4x4 but it is a GM product.
I have a 2000 Pontiac Montana with 138K on it. I changed the trans filter and fluid at 70K.
I noticed last night the transmission was making a whining sound. The best way to describe it is when you turn your radio to an AM station and it picks up the hum from the motor. High pitched. If I gave it gas real quick and let off it would quit.
It runs at 2500rpms now where as it used to run at 2000rpms. When you let up going down a hill it used to slow down by the transmission. The tack drops to 800rpms like it is in neutral. Then when you go up the hill the tack shoots back up to 2500 and you feel the lurch.
If you switch between "D" and "3" there is no change in the rpms at all. However when using "3" it does slow down like it should down hills.
For the last 6 months or so it would shift rough between gears. if you shut it off, let it set for a minute or two then restart it, it would shift smooth again. Sticking solenoid??
Have I lost overdrive or is it something sticking? I am going to change the filter and fluid tomorrow evening and see what happens. Very easy to change. Any additives I should add? My mechanic suggested a bottle that was red colored but for the life of me I cannot recall what it was called. I just never got around to changing it. He said that sometimes can help the sticking solenoid.
Any ideas?
Thanks!!
Lannie