CAMPAIGN: SOFT 1-2 UPSHIFT SLOW ENGAGEMENT

General Motors has determined that some early production 1982 CK20-30 Series Trucks with RPO LL4 (Heavy Duty 6.2L Diesel Engine) and RPO M40 (THM 400 Transmission) may experience a transmission clutch which is slow to engage, a condition which may not be detectable to the vehicle operator.

To prevent the possibility of this condition occurring, it will be necessary to adjust the engine vacuum regulator setting and install a new vacuum modulator on the transmission assembly according to the instructions contained in this bulletin. If this condition is not corrected, premature transmission clutch wear may occur.

VEHICLES INVOLVED

Involved are some early production 1982 CK20-30 Series Trucks with RPO LL4 (Heavy Duty 6.2L Diesel Engine) and RPO M40 (THM 400 Transmission) within the following parameters:

Plant From Through ----- ---- ------- St. Louis CS101665 CS101869

Pontiac CV101392 CV102451

Involved vehicles have been identified by Vehicle Identification Number Computer Listings. Computer listings contain the complete Vehicle Identification Number, Owner Name and Address Data, and are furnished to the involved Dealers with the campaign bulletin. Owner name and address data furnished will enable dealers to follow up with owners involved in this campaign.

These listings may contain owner names and addresses obtained from State Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing for the follow-up necessary to complete this campaign.

Any dealer not receiving a computer listing with the campaign bulletin was not shipped any involved vehicles.

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of Owner Letter included with this bulletin).

DEALER CAMPAIGN RESPONSIBILITY

This recall campaign is to be performed at no charge to owners on all affected vehicles regardless of time, mileage, or ownership. Dealers are to inspect and 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 be sure the campaign correction has been made.

SERVICE PROCEDURE

Transmission-Vacuum Modulator Inspection and/or Replacement.

1) Raise vehicle.

2) Inspect vacuum modulator.

o If the vacuum modulator is (white), no further action is required.

o If vacuum modulator is (black), replace with P/N 359917.

Replacement procedure for vacuum modulator may be found in the 1982 Light Duty Truck Shop Manual, Section (400) 7A, Page 57.

3) Lower vehicle.

Engine-Vacuum Regulator Reset Procedure.

1) Open hood and remove air cleaner.

2) Locate the vacuum regulator (on the forward end of the fuel injection pump).

3) Loosen both vacuum regulator holding screws to finger loose. Do Not Remove the screws. Refer to illustration.

4) Rotate the valve full clockwise.

5) Tighten both vacuum regulator holding screws to 7-11 N.m. (5.2-8.1 lb. ft.).

6) Do not adjust any other screws.

7) Install air cleaner.

8) Install campaign label according to instructions contained in this bulletin.

9) Close hood.

PARTS INFORMATION

Parts required to complete this campaign are to be ordered by the dealer from the Warehousing and Distribution Division of General Motors (WDDGM).

Part Number Quantity Description ----------- -------- ------------ 359917 1 Modulator (White)

CLAIM INFORMATION

Submit a Product Campaign Claim with the information indicated below:

Parts Failed **Parts Failure Labor Labor *Other Count Part No. Allowance Code Operation Hours Hours ----- ------- --------- ---- ---------- ----- ----- 00 V1190 .3 .1

Description: Reset engine vacuum regulator and inspect transmission vacuum modulator-no further action required.

1 359917 00 V1191 .5 .1

Description: Reset engine vacuum regulator and install new transmission vacuum modulator.

*Campaign Administrative Allowance

**The Parts Allowance should be the sum total of the current WDDGM Dealer Net plus 30% of all parts required for the repair.

Dealers will automatically receive the correct parts and labor allowance based on the Labor Operation performed.

Refer to the Chevrolet Claims Processing Manual for details on Product Campaign claim submission.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle modified in accordance with the instructions outlined in this Product Campaign Bulletin will require a "Campaign Identification Label". Each label provides a space to include the five digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or ballpoint pen.

Each "Campaign Identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in for periodic servicing by the owner.

Apply "Campaign Identification Label" only on a clean dry surface.

ADMINISTRATIVE PROCEDURE

REFER TO THE CURRENT CHEVROLET SERVICE POLICIES AND PROCEDURES MANUAL AND CLAIMS PROCESSING MANUAL FOR CAMPAIGN HANDLING AND ADMINISTRATIVE PROCEDURES.

Dear Chevrolet Owner:

General Motors has determined that some early production 1982 CK20-30 Series Trucks with RPO LL4 (Heavy Duty 6.2L Diesel Engine) and RPO M40 (THM 400 Transmission) may experience a transmission clutch which is slow to engage, a condition which may not be detectable to the vehicle operator.

To prevent the possibility of this condition occurring on your vehicle, it will be necessary to adjust the engine vacuum regulator setting and install a new vacuum modulator on the transmission assembly. If this condition is not corrected, premature transmission clutch wear may occur. Instructions have been sent to your Chevrolet Dealer.

Please contact your dealer to arrange a service date to have the engine vacuum regulator setting adjusted and the transmission vacuum modulator inspected, and if required, replaced. The labor time to perform the modification is approximately thirty(30) minutes. The modification will be performed at no charge to you.

The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will assist him in making the necessary correction to your vehicle in the shortest possible time. If you have sold or traded your vehicle, please let us know by completing the postage paid owner reply card and returning it to us.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products.

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.