GM Service Manual Online
For 1990-2009 cars only

1-2 SHUDDER/CHUGGLE OR DOUBLE BUMP

TRANSMISSION APPLICATIONS: 4180E/4L80-EHD,6.2L DIESEL

SUBJECT: 1-2 SHUDDER,CHUGGLE OR DOUBLE BUMP (NEW T.C.M. PACKAGE)

TRANSMISSION MODELS:

VEHICLE APPLICATIONS: 91 C/K,R/V,P TRUCK; G VAN W/4L80-E /4L80-EHD AND 6.2L DIESEL

SERVICE INFORMATION:

Some 6.2L Diesel HYDRA-MATIC 4L80-E/4L80-EHD Transmissions with either 100 AMP or 105 AMP alternators (RPO's K60 and K68, respectively) may experience a 1-2 shudder, chuggle or double bump. This condition is created by excessive transmission line pressure oscillations caused by the force motor circuitry short protection transistor Q6 which is located within the T.C.M. (Transmission Control Module).

A new T.C.M. package has been released that eliminates this condition.

DATE OF PRODUCTION CHANGE: Refer to Figure 1 ---------------------------------------------- Starting October 23, 1990 (Julian Date 296) all CAP, CBP, CKP and CRP HYDRA-MATIC 4L80-E/4L80-EHD transmission models were built with this new Transmission Control Module.

SERVICE PROCEDURE:

Diagnostics of this situation involves disconnecting the 4-wire (P.L.1,5) connector on the alternator and duplicating the complaint. Should the complaint be alleviated by the above procedure, a new T.C.M. will have to be installed. Refer to your 4L80-E Diagnostic Section of the Service Manual if the condition still exists.

SERVICE PARTS INFORMATION:

Part # Description Transmission Models -------- ------------------------ -------------------- 16147609 Pkg. - Transmission Control Module/ CPAP,CBP,CKP,CRP with Instruction Sheet

SERVICE MANUAL REFERENCE:

Refer to appropriate Service Manual replacement procedures.


Object Number: 83345  Size: FS

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.