ALTITUDE ADJUSTMENT PROGRAM CONVERSION PROCEDURES & P/N'S

General Motors did not offer an Altitude Emissions Package as an option for the 1981 model year. Instead, the Environmental Protection Agency has approved certain adjustments on 1981 passenger vehicles built and certified for operation at low altitudes but delivered by dealers located at 4,000-foot altitudes or higher.

The approval of these adjustments is STRICTLY LIMITED TO THOSE DEALERSHIPS LOCATED AT ALTITUDES OF 4,000 FEET OR HIGHER, IN COUNTIES DESIGNATED BY EPA AS HIGH ALTITUDE COUNTIES FOR THE 1977 MODEL YEAR (Refer to the attached map and listing).

ALTITUDE ADJUSTMENT LABEL

When LOW ALTITUDE vehicles (Federal or California) are adjusted for high altitude operation, a SUPPLEMENTAL Emission Control Information Label (See Figure 1) must be placed next to the existing underhood Emission Control Information Label. Wash off the area with soap and water, dry thoroughly, and apply the new label.

DEALER AND CUSTOMER INFORMATION

Dealers located at 4,000-foot elevations or higher, in counties designated by EPA as high altitude counties for the 1977 model year, should perform these adjustments prior to delivery of a new 1981 vehicle to the customer. Owners of 1981 low altitude vehicles, purchased in low altitude areas, taking up permanent residence in one of these high altitude counties should be encouraged to have these adjustments performed when vehicles are brought in for service.

After performing these adjustments, dealers must advise customers that, IF THE VEHICLE IS RETURNED TO CONTINUOUS, LOW ALTITUDE OPERATION, THE ENGINE MUST BE READJUSTED TO LOW ALTITUDE.

PARTS INFORMATION

The injection pump altitude conversion kit is available through GMWDD, part number 22513965.

Kit Contents Quantity ------------ --------- Locknut 1 Seal 1 Metering Valve Screw 1 Label 1 Instruction Sheet 1

SPECIAL TOOLS REQUIRED

All tools or equipment required to perform these adjustments are presented in detail in Cadillac Chassis Service Manuals and include the following:

- intake air crossover screen J-26996-2 - magnetic tachometer J-26925

1981 INJECTION PUMP PROCEDURE FOR CONVERSION TO HIGH ALTITUDE APPLICATION

1. Set idle speeds to specification.

2. With engine off but at normal operating temperature, transmission in park and air conditioner off, remove air cleaner and air crossover.

3. Cap intake manifold with (J-26996) screen covers.

4. Remove pressure tap plug and seal located on the rear of the pump, Figure 2.

5. Assemble locknut and new seal to metering valve stop screw as shown in Figure 2. Recessed surface of locknut should be at midpoint of metering valve stop screw.

6. Install assembly in injection pump until locknut contacts pump housing. Tighten locknut.

7. Insert probe of (J-26925) magnetic pick-up tachometer in timing indicator hole and start engine.

8. Loosen locknut and slowly turn metering valve stop screw clockwise until idle speed drops approximately 10 RPM.

9. Turn metering valve stop screw counterclockwise 1-1/2 turns and tighten lock-nut.

10. Check installation for fuel leaks.

11. Turn engine off.

12. Remove magnetic tachometer probe and screened covers from intake manifold and reinstall parts removed.

ALTITUDE ADJUSTMENT LABEL

Supplemental Vehicle Emission Control Information Label, in kit part number 22513965 with the legend DIESEL PROCEDURE must be installed. Refer to the installation instructions covered previously in this bulletin.

HANDLING OF ALTITUDE ADJUSTMENT EXPENSE

1. Predelivery - The adjustment should be performed at time of predelivery by those dealers in designated high altitude counties delivering a 1981 diesel engine equipped Cadillac to an owner residing in a designated high altitude county. (Refer to list of high altitude counties enclosed.)

2. Owners who live in a high altitude county and have taken delivery of a 1981 diesel engine equipped Cadillac prior to this bulletin - Dealers in designated high altitude counties are to encourage owners to have the high altitude adjustment performed. Such adjustments performed on a 1981 diesel engine equipped Cadillac are to be submitted as a warranty claim.

Credit for high altitude adjustments performed on vehicles described in number 1 or 2 above will be issued upon receipt of a properly prepared warranty claim as follows:

Part Part Failure Labor Labor Description Count Number Code Operation Time ----------- ----- ------ ---- ---------- ---- Diesel High Altitude 1 22513965 95 T0012 .5 Hours Adjustment

3. Owners who move to high altitude counties - Dealers in high altitude areas should encourage owners who have moved to high altitude counties to purchase this adjustment service which is considered an owner maintenance expense.

4. Owners who move from high altitude counties - Dealers must advise owners moving to low altitude areas that the engine must be readjusted to "Low Altitude" configuration by removing the metering valve stop screw and reinstalling the pressure tap plug and removing the high altitude label. This is considered an owner maintenance expense.

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 Esmeralda 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 Summit 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 Summit Bannock Custer Emery Tooele Bear Lake Franklin Grand Uintah Bingham Fremont 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.