CAMPAIGN: LOW (TPS) OUTPUT (INSPECT/REPLACE TPS SWITCH). GMC Truck GMC R Truck

Subject: THROTTLE POSITION SENSOR

Models: 1991 C/K, R/V and P Trucks, and G Vans -----------------------------------------------------------------------------

TO: ALL AFFECTED DEALERS:

General Motors of Canada has determined that certain 1991 C/K, R/V and P trucks and G vans with 4.3L, 5.7L or 7.4L fuel-injected gasoline engines, coupled with Hydra-Matic 4L80 electronic transmissions (MT1), may have a Throttle Position Sensor (TPS) which exhibits intermittent low output voltage. This condition may cause the transmissions in these vehicles to have no overdrive and/or harsh transmission shifts. To correct this condition, dealers are to inspect and, if necessary replace, the TPS switch.

VEHICLES INVOLVED:

Involved are certain 1991 C/K, R/V and P trucks and G vans with 4.3L, 5.7L or 7.4L fuel-injected gasoline engines, coupled with Hydra-Matic 4L80 electronic transmissions (MT1) built within the following VIN breakpoints:

PLANT YEAR MODEL PLANT CODE FROM THROUGH ---- ----- ----- ----- ---- ------- CHEVROLET 1991 C/K Oshawa 1 M1102376 M1215247 1991 C/K Fort Wayne Z MZ111026 MZ162490 1991 C/K Janesville J MJ1OOOO9 MJ1O9467 1991 C/K Pontiac East E ME100001 ME189057 1991 R/V Flint F MF100003 ME137073 1991 P30 Detroit 3 M3300001 M3310669 1991 G Lordstown 7 M7118501 M7127389 1991 G Scarborough 4 M4100019 M4133305

GMC 1991 C/K Pontiac East E SOP ME534777 1991 C/K Oshawa 1 SOP M1541745 1991 C/K Janesville J SOP MJ519682 1991 R/V Flint F SOP MF520807 1991 P Detroit 3 SOP M3501970 1991 G Lordstown 7 SOP M7512706 1991 G Scarborough 4 SOP M4512352

All affected vehicles have been identified by the VIN listing provided to involved dealers with this bulletin. Any dealer not receiving a listing was not shipped any of the affected vehicles.

DEALER CAMPAIGN RESPONSIBILITY:

Dealers are to perform this campaign on all involved vehicles at no charge to owners, regardless of kilometres traveled, age of vehicle, or ownership, from this time forward.

Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service, you are to ensure the campaign correction has been made before selling or releasing the vehicle.

Owners of vehicles recently sold from your new vehicle inventory are to be contacted by the dealer, and arrangements made to make the required modification according to instructions contained in this bulletin.

CAMPAIGN PROCEDURE:

Refer to Section 4 of the Service Policies and Procedures Manual for the detailed procedure on handling Product Campaigns. Dealers are requested to complete the campaign on all transfers as soon as possible.

OWNER NOTIFICATION

All owners of record at the time of campaign release are shown on the attached computer listing and have been notified by first class mail from General Motors. The listings provided are for campaign activity only and should not be used for any other purpose.

PARTS INFORMATION

Parts required to complete this campaign should be ordered through regular channels, as follows:

Part Number Description Quantity/Vehicle ----------- ----------- --------------- 17112679 Throttle Position Sensor (TPS) Kit 1

PARTS AND LABOUR CLAIM INFORMATION:

Credit for the campaign work performed will be paid upon receipt of a properly completed campaign claim card or DCS transmission in accordance with the following:

Repair Code Description Time Allowance ----------- ------------ -------------- 1A Inspect - TPS Does Not Need Replacement .3 - C/K & R/V

Inspect - TPS Does Not Need Replacement .5 -G&P

2A Inspect and Install TPS Kit .6 - C/K & R/V

3A Inspect and Install TPS Kit .7 -G&P

Time allowance includes 0.1 hour for dealer administrative detail associated with this campaign. Parts credit will be based on dealer net plus 30% to cover parts handling.

SERVICE PROCEDURE:

1. Remove air cleaner (if necessary).

2. Inspect vehicle's TPS for yellow dot. If the TPS has a yellow dot at the connector area, skip to step 4 below.

3. If the TPS does not have a yellow dot, replace the TPS with the new TPS kit per the Fuel And Emissions Section of the appropriate service manual.

4. Install Campaign Identification Label.

INSTALLATION OF CAMPAIGN IDENTIFICATION LABEL

Clean surface of radiator upper mounting panel and apply a Campaign Identification Label. Make sure the correct campaign number is inserted on the label. This will indicate that the campaign has been completed.

Notification

September 1991

Dear General Motors Customer:

General Motors of Canada has determined that the throttle position sensor (TPS) on your 1991 truck/van may exhibit an intermittent low-output voltage. This condition may cause your transmission to have no overdrive and/or harsh transmission shifts.

To correct this condition, the existing TPS in your vehicle will be replaced with a new updated part. This service will be performed for you at no charge.

Please contact your GM dealer as soon as possible to arrange a service date.

This letter identifies your vehicle. Presentation of this letter to your dealer will assist their Service personnel in completing the necessary correction to your vehicle in the shortest possible time.

Subsequent to contacting your dealer, further assistance, if required, may be obtained from our Customer Assistance Centre, toll free, by calling 1-800-263-3777 (English), or 1-800-263-7854 (French).

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.