2500 4x2 Pickup V8-5.9L VIN Z (1994)
Overdrive Assembly: All Technical Service Bulletins
A/T - Driveline Clunk on 4-3 Downshift
NO: 21-18-94
GROUP: Transmission
DATE: Sep. 30, 1994
SUBJECT:
4 Speed Automatic Transmission 4-3 Downshift Clunk
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 21-39-93 DATED DEC. 31, 1993 WHICH SHOULD BE NOTED IN YOUR
FILES. THE COMPLETE REPAIR PROCESS HAS BEEN CHANGED. A NEW OVERDRIVE CLUTCH PISTON AND SPACER SELECTION
PROCESS ARE INCLUDED.
MODELS:
1988 - 1994
(B)
(AB)
Ram Van/Wagon
1988 - 1993
(D)
(AD)
Ram Pick Up/Ram Cab & Chassis
1988 - 1994
(N)
(AN)
Dakota/Dakota Sport/Dakota Cab & Chassis
1993 - 1994
(ZJ)
Grand Cherokee
1994
(BR)
Ram Pick Up/Ram Cab & Chassis
SYMPTOM/CONDITION:
Driveline clunk or harshness during 4-3 closed throttle coast down downshift (approximately 18-20 MPH).
DIAGNOSIS:
With the overdrive on (light off), operate the vehicle to verify that the clunk occurs at approximately 18-20 MPH while coasting with the throttle closed.
Make sure the transmission is in overdrive (4th gear) before starting the coast down. Repeat with the overdrive off (use O/D switch on the instrument
panel - light on). Do this procedure several times with overdrive on and then off. If the clunk occurs only when the overdrive is on, proceed to the repair
procedure.
If the clunk occurs during both test phases, overdrive on and overdrive off, look for other possible causes such as driveline backlash, shift cable/linkage
adjustment or low transmission oil level. Repair as required.
PARTS REQUIRED:
REPAIR PROCEDURE:
This bulletin involves the removal of the overdrive unit and replacement of the overdrive piston and if needed, an overdrive piston thrust plate spacer.
1.
Shift transmission into Park. Raise the vehicle.
2.
Remove the transmission oil pan, remove gasket, drain oil and reinstall pan.
3.
If the overdrive unit has malfunctioned or if fluid is contaminated, remove entire transmission. If diagnosis indicated overdrive clutch or governor
