The shift points are somewhat controlled by the throttle position
sensor. The plug and socket on it get corroded. I clean them with a
spray contact cleaner, then use some dielectric grease on the plug seal
skirt which seems to last at least a couple years.
WD40 will also work as a cleaner in a pinch, but the job doesn't last
If cleaning doesn't help, then you can test it with a multimeter. On
ohms, it will vary the resistance going up on the center wire and one
side wire, and vary going opposite on the center wire and the other side
wire. The resistance must be smooth.
There are voltage tests for it too. You have the engine key on run and
backprobe the plug. The voltage should go from .02V to 4.8V. Same deal
as above, one side goes up from .02 and the other side goes down to
0.02V and it must be a smooth transition.
Hope this helps,
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
> My Jeep cherokee 4x4 has an automatic transmission with overdrive.The
> problem I am having is with the transmission not wanting to shift. In
> order for me to get it to shift i litterally have to wind the engine out.
> It shifts from low to second gear at 35 mph and then will not shift into
> the next gear until you reach 65 mph. It seems to be intermittant as
> yesterday when I first drove it it worked perfectly but later the same day
> it started acting up again and still is not right. Can anyone give me some
> advise. I am thinking that it could be the electronic shifting control
> module, but I know nothing about this, Thanks >> Stay informed about: My 1990 Jeep Cherokee won't shift