K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Technical Service Bulletin # 90C26A
Date: 931001
Preliminary Information
GMC NUMBER: 90-C-26(A)
GROUP: 7A Auto. Transmission
DATE: October 1993
SUBJECT:
AUTOMATIC TRANSMISSION FLUID CONTAINMENT
MODELS:
1988-90 C/K TRUCKS AND R/V SUBURBAN
THIS CAMPAIGN UPDATES AND REPLACES GMC CAMPAIGN NUMBER 90-C-26, ISSUED JANUARY 1992, TO INCLUDE 1986-90 R/V
SUBURBANS. DESTROY ALL COPIES OF 90-C-6.
THIS CAMPAIGN HAS BEEN REVISED TO INCLUDE THE ADDITION OF R/V SUBURBANS TO THE POPULATION OF AFFECTED
VEHICLES.
Product improvements were made on all 1991 C/K Trucks and R/V Suburbans equipped with automatic transmissions to help in maintaining the proper
transmission fluid level. Transmission fluid level is very important to transmission life and performance; therefore, GMC Truck will make these
improvements on 1988-1990 C/K Trucks and R/V Suburbans.
Also, it has come to our attention that some owners are pulling trailers heavier than the vehicle is equipped to pull or loading vehicles with loads greater
than that specified for the vehicle as it is equipped. These conditions can result in abnormal pressure build-up in the transmission and the possibility of
transmission fluid coming out the filler tube onto hot engine parts.
The possibility of a transmission fluid fire is remote. However, we wanted our owners to have the benefits of the improvements which address this
concern, and the maintenance of a proper transmission fluid level.
These improvements consist of (1) revising the transmission fluid level indicator (dipstick) markings so they can be more easily understood, (2) adding a
seal at the fill tube inlet end to help prevent fluid from coming out of the fill tube, and (3) revising the fluid level checking procedure in the owner's
manual to provide for a "cold" fluid level check. (Note: a "hot" check must follow when fluid is added during a cold check).
To help prevent conditions that could cause transmission pressure build-up and the possibility of transmission fluid coming out of the fill tube, General
Motors is providing, to owners, a new dipstick with a lock-seal top and new owner manual instructions and graphics for checking the automatic
transmission fluid level.
VEHICLES INVOLVED
Involved are 1988-1990 C/K Trucks and R/V Suburbans with a 4L60 (RPO MD8) or 3L80 (RPO M40) automatic transmissions.
The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer Listings. These listings are furnished to
all involved dealers with the campaign bulletin. Dealers should confirm vehicle eligibility through VISS (Vehicle Information Service System) prior to
beginning campaign repairs.
DEALER CAMPAIGN RESPONSIBILITY
Since a new dipstick can be installed easily, a new dipstick along with installation instructions will be sent directly to owners of record. Owners may
install the dipstick or they may ask a dealer to complete this service. Also, an owners manual supplement will be sent to owners along with the dipstick
and installation instructions.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of mileage. age of vehicle, or ownership, from this time
forward. Dealers are to correct all affected vehicles in new and used vehicle stock prior to their sale.
Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service in the future, you
should take the steps necessary to ensure the campaign correction has been made before reselling or releasing the vehicle.
