628 Dtc

Pulled the code because of a flashing O/D light with "excessive converter clutch slippage". No other problems with the tranny other than no O/D. If I clear the code by disconnecting the battery, it will come back after a couple of days. The tranny has had a fluid flush and is topped up but has not solved the problem. Will a valve body rebuild help? When I searched the site, I couldn'd find anyone with this particular problem.

Not as familiar with the 4R44E, but I'll try to help.
From what I can gather, the 4R44E has sensors for th crankshaft, input shaft, and output shaft. When the EEC-IV computer tells the torque converter clutch (TCC) to lockup, it monitors the crankshaft sensor and the input shaft sensor to see if they are nearly the same. If they aren't, then that trouble code is set. Problems in the valve body are certainly a possible cause, and rebuilding the valve body would fix it, if the problem is in the valve body. In addition to the valve body, an electrical fault between the computer and the TCC solenoid could conceivably prevent the signal to lock from getting to the transmission and trigger that code. A problem in the torque converter itself could also cause it. Personally, I would start with the electronics to make sure they work right before going to the hydraulic/mechanical.

I hate to ask this, but I feel I must if we are to understand your problem. You say that it works fine except for no OD and this trouble code. Some people mistakenly call TCC lockup "overdrive" when overdrive, in fact, refers to 4th gear. When you say overdrive, to which are you referring: 4th gear or TCC lockup? Not a big deal -- just want to be clear on whether you have one or two problems.

I can feel the TC lock up but it will not shift into 4'th. Please don't hesitate to ask any question, I appreciate the input.

I wish I could help better with the 4R44E. Best I've got is to check the wiring from the computer to the 3-4 shift solenoid. Using the computer's output state test and a voltmeter, you can check to see that the computer can switch the solenoid. If the computer control of the 3-4 shift is working, it's likely to be a hydraulic/mechanical fault inside the transmission.

Check out this TSB 98-15-06
LIGHT TRUCK: 1995 EXPLORER


This TSB article is being republished in its entirety to update the Service Procedure.

CALIBRATION:
5-58B-R10, 5-58R-R10

WARNING: THIS MODIFICATION IS AUTHORIZED ONLY FOR THE LISTED ENGINE. PERFORMING THIS MODIFICATION ON OTHER ENGINE CALIBRATIONS IS UNAUTHORIZED AND COULD CREATE LIABILITY UNDER APPLICABLE FEDERAL OR LOCAL LAWS.



ISSUE:
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.

ACTION:
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.



PCM APPLICATION
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


Obtain an Authorized Modifications Decal (FPS 8262 - orderable through DOES II, 25/pkg) and list the date, dealer number, and summary of alterations performed. Select a prominent place adjacent to the Vehicle Emission Control Information Decal suitable for installing the Authorized Modifications Decal. Clean the area, install the decal, and cover it with a clear plastic decal shield.




PART NUMBER PART NAME
F5PZ-12A650-BRA Powertrain Control Module (PCM)
F5PZ-12A650-BSA Powertrain Control Module (PCM)



OTHER APPLICABLE ARTICLES:
95-19-12 , 97-17-24

SUPERSEDES:
98-3-21