Torque Converter - Shudder/Noise on Lock-up

91isuzu05

BULLETIN NUMBER
SB91-05-005


ISSUE DATE
August 15,1991


GROUP
TRANSMISSION


TROOPER II (KT) AND RODEO (UC) TORQUE CONVERTER SHUDDER


AFFECTED VEHICLES

1990-91 Trooper II (KT) and Rodeo (UC) models with V6 engine equipped with 4L30-E automatic transmission.

SERVICE INFORMATION

Affected vehicles may experience a shudder or engagement noise from the transmission area at torque converter lock-up when driving 45-50 mph at cruise or light throttle after 4th gear upshift. This noise is caused by insufficient torque converter damper vibration absorption. Installing a new, improved torque converter (listed in the "Parts Information" section of this Service Bulletin) will eliminate the shudder or engagement noise.

SERVICE PROCEDURE

1. Obtain a complete description of the complaint from the customer.

2. Check to see if any trouble codes are present in the TCM. If any codes are present, refer to the "Electronic Diagnosis" section of the appropriate Workshop Manual.

NOTE
Transmission Control Module (TCM) circuit failures may cause vibrations and noises similar to those caused by the torque converter clutch damper, however, replacing the torque converter will not correct TCM circuit failures.

CAUTION
The following test drive requires driving the vehicle with incorrect brake light operation. Do not conduct this test drive on a public thoroughfare.


3. Test drive the vehicle as follows:

While maintaining steady speed in 4th gear with the torque converter in "lock-up", lightly touch and release the brake pedal, watching the tachometer rpm fall and rise, indicating torque converter release and lock-up.

a. If the shudder or noise is felt or heard at any time other than during torque converter "lock-up" after 4th gear upshift, refer to the Workshop Manual section titled "Troubleshooting for Mechanical/Hydraulic Faults".

b. If the shudder or noise is felt or heard only on torque converter "lock-up" after 4th gear upshift, continue with this Service Procedure.

4. Remove the transmission assembly as described in the appropriate Workshop Manual.

5. Remove the torque converter from the transmission.

6. Install a new, improved torque converter (see "Parts Information" section of this Service Bulletin).

7. Reinstall the transmission assembly as described in the appropriate Workshop Manual.

8. Add automatic transmission fluid (ATF) to the properlevel.


PART NUMBER INFORMATION


Part No. Description

8-08680-188-0 Torque Converter (Trooper)

8-08680-189-0 Torque Converter (Rodeo)


FLAT RATE MANUAL INFORMATION


OPERATION SPECIAL ADDITIONAL
OPERATION NUMBER TASK INSTR. TIME INSTRUCTIONS

Torque Converter 050601 Replace PT 6.0 Includes: 050658 R&R
AUTH Automatic Transmission
Assy.