Ford Explorer Transmission

I bought a 1995 Ford Explorer with 110000. Had it checked out by a mechanic before buying. 2 weeks after buying it, the o/d light began flashing on the dash indicating a problem with the transmission. Took it to a transmission shop for repair. They replaced some pistons and gaskets in the transmission and the flashing light was off when I picked the vehicle up. By the time I got home (about 50 miles), the light was flashing again. Took it back to the shop, they replaced the computer. Same thing–by the time I got it home, the light was flashing again. Took it back to the shop-- the transmission was practically rebuilt (according to them). This time the light remained off for about 1000 miles and the transmission performed smoothly. Got great gas mileage. Then the o/d light came back on and the transmission shifts roughly and the gas mileage has tanked (pardon the pun). The transmission shop says there is nothing wrong with the transmission. Their work is still under their warranty that is why I have stuck with them rather than going to another shop.

Anyone have a similar experience with a Explorer Trans and what did you do to fix it?

OD light flashing simply indicates that the engine management system has identified a transmission malunction. This could be the result of a multitude of problems. We’re going to need some additional info from you. Having the actual faults codes listed here would give us a starting point.

You stated that the transmission shifts roughly, curious does it shift roughly in all gears (1st thru 4th). How about park to drive range, park to reverse, reverse to drive?

Are all gears present (1st thru 4th)? Are all upshift ans downshifts harsh?

You concern may not be a mechanical issue within the transmissions but rather an electrical circuit fault.

What codes are they pulling from the computer?? Do they keep getting the same codes??


Thanks for your response Jagree142 and Transman618. The rough shifting is usually downshift, second to first. Upshifting is about the same. For the brief time that the o/d light was not flashing, the shifting was smoother.

I just got in from getting the vehicle from the shop and once again the o/d light started flashing before I got it to the house about 50 miles from the shop.

Here are the notes that were made by the people at the transmission shop. “hooked up hand held scan tool, monitored signals from TPS, VSS, and A & B solenoids. Checked for and cleared codes. Test drove, vehicle had several engines codes and 1 transmission code. Codes Found 172 EGO, 176 EGO and 647-incorrect 3rd gear ratio.” Here is what they tried on the vedicle–hooked up a line pressure guage and checked pressure–135-140 psi in drive, which was good. Removed pan and checked for condition in pan,it was very clean. Adjusted the EPC solenoid up by about 10PSI and installed new pan gasket and filled with fluid. Rechecked PSI line. Installed an extra grounding strip from the transmission to the frame. Test drove with scanner and vehicle did not reset code. I was told that they had also put a new wiring harness on the trans as well.

There is no slipping in the transmission so I would assume there it is a false code. The vehicle does not run as smoothly with the o/d light flashing. Again, I assume that the computer and the transmission are out of sync because of the false code.

There is a TSB for intermittent OD light flashing with codes 645 or 646 or 647 or 648.
647 as you mention idicates that the PCM has detected loss of third gear.
You will need to follow TSB 98-5-16.
As read below:
5-58B-R10, 5-58R-R10


Some vehicles may experience a flashing “O/D OFF” lamp and/or the following Diagnostic Trouble Codes (DTCs) may occur: 645, 646, 647, 648. This may be caused by a damaged intermediate and/or overdrive servo piston seal, faulty Throttle Position (TP) sensor wiring or a concern with the transmission control strategy.

Follow the diagnostic procedures listed in the 1995 Explorer Service Manual and the following text for details.

Service all non-transmission DTCs and concerns first.

Service all transmission DTCs and concerns except for DTCs 645, 646, 647, 648.

For the above DTCs, follow TSB 97-17-24 making sure that the Electronic Pressure Control (EPC) solenoid is functional, transmission bands are adjusted properly, and the servos are not damaged.

Check the TP sensor wiring, wiring crimps, and peform a wiggle test.

If after checking the transmission and TP wiring no problems were identified, verify the vehicle has the latest level calibration. If it does not, replace the Powertrain Control Module (PCM). Refer to the following PCM Application Chart for correct PCM usage.

Old Calibration Old Part Number (-12A650-) New Calibration New Part Number (-12A650-)
5-58B-R10 F5TF-ARC 5-58B-R10 F5PF-BRA
5-58R-R10 F5TF-ATC 5-58R-R10 F5PF-BSA

NOTE: Another item to inspect before for you go crazy with PCMs and calibrations… YOu have both bank lean codes… Air fuel ratio calculation is based on MAF reading… If MAF or TP are erratic, engine load calculation will be biased… This load calculation is used for transmission control. Either Line pressure will be high or low depending on system bias. Vehicle is a bit old to suddenly have calibration issues, however PCM failure may be possible.You should rule out the basic PCM inputs and basic driveability issues first. Fuel Pressure? MAF reading at idle and on accel, IAT and TP variability/inconsistency.

You must get the engine performance side back first, then deal with transmission second. Once driveability is cleaned up, then bands and servos should be checked. I would only assume the transmission shop did verify the servo and band integrity. But then again in this business you can’t assume anything.

Thanks Jagree142, I’ll show your suggestions to the shop. Hopefully, that will take care of the problem.