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A4LD strange problem


New Member
February 27, 2006
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Year, Model & Trim Level
'91 XLT
Can someone help me? I am pulling my hair out trying to fix this problem.

91 Explorer 4WD. Trans started acting up all of a sudden. When you select OD, it has no forward movement. If you shift to D, the truck will drive fine upshifting and downshifting at the proper points. When I get out on the highway at 55+ I can shift back to OD and everything functions as it should. Trans shifts to 4th, TC locks up and all is well. Going up a hill, the TC unlocks, and trans shifts down to 3rd if needed. Once the speed drops below ~50mph where it would normally shift to 3rd, the trans starts 'slipping' again. If I shift back down to D, everything is fine. Reverse is fine.

Because of this, I rebuilt the transmission and VB, replaced all seals, frictions, steels, bands and any hard part that looked sketchy (also put in a new TC). Put the transmission back in, same symptons as before. I searched around the forum for ideas and dropped the trans a second time, went through everything a second time, replaced both solenoids and servos, replaced vac. modulator, checked and cleaned the governor again, went through the valve body again, did all the air pressure checks, fluid pressure checks, stall tests, made sure the trans was getting the proper signals from the computer for 3-4 shift and TC lockup and it was. Back in the truck again, same symptoms...

Basically, HELP!!! I am out of ideas...

I'll post this incase others have this problem.

It turns out that the OD sprag was shot. Replaced the sprag and presto!