For 1990-2009 cars

# THM 440-T4 HARSH UPSHIFTS HIGH ALTITUDE

#### MODELS AFFECTED: 1985-1986 DE VILLE AND FLEETWOOD 1986 ELDORADO AND SEVILLE

Some 440-T4 transaxles operated in designated high altitude areas may exhibit harsh upshifts. It is also possible to experience the condition in any mountainous elevation above 4,000 feet.

The condition is the result of low engine vacuum to the vacuum modulator causing high line pressure. To correct the condition, an aneroid vacuum modulator kit has been released. The following service packages have been released for specific model identification codes.

Transaxle Service Package Model Identification --------------- ---------------------

8646966 5AM, 5AR, 5AF, 6AMH, 6AAH, 6ABH, 6ACH, 6AFH

8646967 6ADH, 6ARH

#### Each Package Contains

Vacuum Modulator (Aneroid) Revised Modulator Valve "O"Ring Seal Valve Body Spacer Plate Gaskets (5) Instruction Sheets (2) Cup Plug (Orificed - See Attachment)

#### IMPORTANT: At the same time a new vacuum pipe from the throttle body to the vacuum modulator must be installed. The new steel line is formed to accommodate relocation of the vacuum connector on the modulator from the end to the side.

#### NOTE: Do not attempt to reform the original steel line or connect the line and modulator with additional hose.

Part Number Description Application ----------- ----------- ------------

1637147 Pipe 1985-86 "C" Car 1641441 Pipe 1986 "E/K" Car

Refer to the appropriate Service Information Manual, 440-T4 Transaxle Unit Repair section for service procedures.

* Attached is a map and list of designated high altitude areas, by county, in the United States.

Use labor operation K6570 at 2.7 hours for De Villes and 3.2 hours for Eldorados and Sevilles.

DESIGNATED HIGH ALTITUDE COUNTIES* Requiring High Altitude Emission Control

STATE OF ARIZONA STATE OF NEVADA Apache Carson City Humboldt Navajo Douglas Lander Elko Lyon STATE OF COLORADO Emseralda Mineral Adams Jefferson Eureka Storey Alamosa Lake White Pine Arapahoe La Plata Archuleta Larimer STATE OF NEW MEXICO Boulder Las Animas Bernalillo Mora Chaffee Lincoln Catron Rio Arriba Clear Creek Mesa Colfax Sandoval Conejos Mineral Curry San Juan Costilla Moffat De Baca San Miguel Crowley Montezuma Grant Santa Fe Custer Montrose Guadalupe Sierra Dolores Morgan Harding Socorro Delta Ouray Lincoln Taos Denver Park Los Alamos Torrance Douglas Pitkin Luna Union Eagle Pueblo McKinley Valencia Elbert Rio Blanco El Paso Rio Grande Fremont Routt STATE OF OREGON Garfield Saguache Gilpin San Juan Lake Grand San Miguel Gunnison Sumit STATE OF UTAH Hinsdale Teller Beaver Piute Huerfano Washington Box Elder Rich Jackson Weld Cache Salt Lake Carbon San Juan Daggett Sanpete STATE OF IDAHO Davis Sevier Duchesne Sumit Bannock Custer Emery Tooele Bear Lake Franklin Grand Uintah Bingham Preamt Iron Utah Blaine Jefferson Juab Wasatch Bonneville Madison Kane Wayne Butte Minidoka Millard Weber Camas Oneida Morgan Caribou Power Cassia Teton STATE OF WYOMING Clark Valley Albany Natrona Carbon Niobrara STATE OF MONTANA Converse Park Beaverhead Madison Fremont Platte Deer Lodge Meagher Goshen Sublette Gallatin Park Hot Springs Sweetwater Jefferson Silver Bow Johnson Teton Laramie Uinta STATE OF NEBRASKA Lincoln Weston Banner Sioux Kimball

*Counties which have substantially all of their area above 4000 ft. Ref. Federal Register, Vol. 42, No. 76, April 20, 1977. pg. 20464

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.