A/T - 4R44E/4R55E Shift Problems/OD Lamp ON
Article No.97-17-24
08/18/97
^ TRANSMISSION - 4R44E/4R55E - EXTENDED SHIFT
AND ENGINE RPM ABOVE EXPECTED LEVELS OR
"NO UPSHIFT" - TRANSMISSIONS BUILT BEFORE
6/20/95
^ TRANSMISSION - 4R44E/4R55E - O/D OFF LAMP
FLASHING AND/OR DIAGNOSTIC TROUBLE CODES
(DTCs) 645, 646, 647, 648, P0731, P0732, P0733,
P0734
LIGHT TRUCK:
1995-96 EXPLORER, RANGER
This TSB article is being republished in its entirety to revise affected vehicles and provide additional information
ISSUE:
On transmissions built before 6/20/95 (Figure 1) an extended shift and a higher engine rpm than expected and/or no shift condition, possibly along with a flashing "O/D OFF" lamp and/or the following Diagnostic Trouble Codes (DTCs) may occur:
^ 645, 646, 647, 648
^ P0731, P0732, P0733, P0734
This may be caused by a damaged intermediate and/or overdrive servo piston
seal.
ACTION:
Follow the diagnostic procedures listed in the appropriate Ranger/Explorer Service Manual and the following text for details.
If the transmission tester indicates that the Electronic Pressure Control (EPC) solenoid and the shift solenoids are functioning properly, verify the intermediate and overdrive bands for proper adjustment.
It either band is out of adjustment, remove the transmission, disassemble and inspect the bands, drums and servo seals for damage. If replacing the servo piston/rod assembly make sure to use the latest service part. Use only service part number -7D021-, manufactured after the 26th week of 1995 and labeled "BRUSS." Refer to the following Chart and Figure 2 for location of the word "BRUSS" and manufacturing date on the servo piston/rod assembly.
Service as required. After servicing the transmission, be sure to clear all DTCs from memory
If the condition returns, perform diagnosis on the Generic Electronic Module (GEM) and Powertrain Control Module (PCM). Refer to the appropriate year Powertrain Control/Emissions Diagnosis (PC/ED) Manual and Service Manual for diagnosis procedures. Service as required.
OTHER APPLICABLE ARTICLES: NONE
SUPERSEDES: 95-19-12
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 206000, 501000