REVISED: HARSH UPSHIFTS / 3-2 SERVICE INFORMATION (440-T4). Chevrolet Celebrity 1984

For 1990-2009 cars

# REVISED: HARSH UPSHIFTS / 3-2 SERVICE INFORMATION (440-T4)

#### MODEL AND YEAR: 1985-86 CELEBRITY WITH 440-T4 TRANSAXLE

A 1985 through 1986 Chevrolet Celebrity equipped with a 2.8L engine and a THM 440-T4 transaxle may exhibit harsh upshifts when operated at high altitudes. This condition may be caused by excessive line pressure resulting from insufficient engine vacuum. Refer to Figure 1 for transaxle identification information.

A new vacuum modulator assembly and modulator valve* have been released for service in a package (P/N 8646956) for the harsh upshifts condition. The package consists of:

-- Transaxle Vacuum Modulator Assembly -- Modulator Valve -- O-Ring Seal -- Instruction Sheet

*Note: A new engine vacuum line (P/N 14062624) must be installed with the service package.

Refer to the appropriate Service Manual for removal and installation procedures as well as to Figure 2 for correct modulator valve orientation.

The service package ONLY applies to the following THM 440-T4 models:

1985 Models 1985 1/2 Models 1986 Models

CW CM CFH CP CN CMH HT HJ CNH HA HJH HBH

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.