93 XLT Shifting Eratically @ 65mph

[Whitecotton]

Hello all, I am a dealer in Fairfield, CA. I recently sold a 93 XLT Explorer to a customer. He brought the truck back today with a shifting problem. He has only put 200 miles on the car, and I want to take care of him. We took a drive today, and at 60-65 mph the truck can't decide what gear it wants to be in. It shifts up and down constantly. It only does it at that mph. 0-60 mph truck drives/shifts great. 65-75 truck drives/shifts great. I serviced the trans when I bought the truck (pan gasket/filter/fluid). Any ideas to help me out? The trans is used that I bought from a third party, and it doesn't sound like he is going to help me out any. Just to answer your curiosity, the truck had only reverse when I got it, thus the "new" trans that I installed. The truck is a push button 4x4 and that works fine. I did a search on here and came up with modulator/kick down cable/band adjustment screws as common answers. I've been working on vehicles for about 10 years, but transmissions are still foreign to me. Thanks for the help.

 

[MrShorty]

We took a drive today, and at 60-65 mph the truck can't decide what gear it wants to be in. It shifts up and down constantly.

Can you tell if it is shifting in and out of 4th gear or is it locking/unlocking the torque converter clutch (TCC)? Do you experience the same behavior in D (which blocks it from shifting into 4th gear, but the TCC can still operate)? If so, that points to something with the TCC.

Both TCC and 3-4 shift are electronically controlled by the PCM. The circuits are fairly straightforward DC circuits. The problem sounds like something in one or both of these "shifts." Usually the first thing I suggest is to determine which shift is having the problem, then determine if it looks like a problem in the electronics controlling the offending shift.