CAMPAIGN: REPLACEMENT PROM INCORRECT COMPRESSION RATIO
MODELS: 1987 G35 VAN OVER 8,500# WITH 5.7L ENGINE (RPO L05, VIN CODE K) AND 3- SPEED AUTOMATIC TRANSMISSION (RPO M40)
General Motors has determined that certain 1987 GMC Truck G35 model vans may have been produced with an engine compression ratio of 9.3:1 rather than 8.6:1 as intended. While there is an improvement in performance, this condition may result in spark knock. To minimize the possibility of spark knock, new PROMS have been released with revised spark advance calibrations which will allow proper engine operation at the increased compression ratio.
VEHICLES INVOLVED
Involved are certain 1987 G35 model vans over 8,500# and equipped with 5.7L engines (RPO L05, VIN Code K) and 3-speed automatic transmission (RPO M40) built within the following parameters:
Plant From Through ----- ----- ------- Lordstown SSV 1987 H7504664 Scarborough SSV 1987 H4502455
The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin.
DEALER CAMPAIGN RESPONSIBILITY
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of mileage, 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 in the future, you should take the steps necessary to ensure the campaign correction has been made before reselling 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 correction according to instructions contained in this bulletin. If no owner's name and address were available to GMC Truck Division at the time of campaign initiation, the dealer will determine the owner's name and address from the dealership sales records. Please provide this information directly on the second copy of the listing next to the applicable VIN so that our records may be updated and the appropriate notification mailed to the owner. This second copy should then be submitted to the address listed below in the previously supplied yellow campaign envelopes.
GMC Truck Division General Motors Corporation 101 Union Street Plymouth, Michigan 48170
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by GMC Truck Division (see copy of owner letter included with this bulletin). A listing of owner names and addresses has been furnished to the involved dealers to enable dealers to follow up with owners involved in this campaign. This listing 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 to this campaign.
SERVICE PROCEDURE
Replace original PROM with new P/N 1228417 PROM. Refer to the 1987 Light Duty Truck Fuel Driveability and Emissions Service Manual (X- 8736), Section 3-103 (Figure 3-39) for instructions on PROM servicing.
PARTS INFORMATION
Parts are to be obtained from General Motors Service Parts Operation (GMSPO). To ensure that these parts will be obtained as soon as possible, they should be ordered from GMSPO on a C.I.O. order with no special instruction code, but order on an advise code (2).
Part Number Description Quantity/Vehicle ------ ---------- ---------------- 1228417 PROM 1
Based on the number of vehicies involved it is recommended that some quantity of parts be ordered upon receipt of this bulletin to allow for part availability upon owner request for vehicle correction.
WARRANTY INFORMATION
Dealers should submit an accurately filled out Warranty Repair Order on each vehicle completed under this campaign.
Labor Operation *Time Trouble Number Description Allowance Code ------ ----------- --------- ---- V4070 Replace .5Hr. 96 PROM
* For dealer to receive Administration Time Allowance associated with this campaign, add 0.1 hour to the Labor Operation Time Allowance.
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected 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 (5) digit dealer code of the dealer performing the campaign service. This informaton may be inserted with a typewriter or ball point 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
Procedures covering this campaign are outlined in Section V of your dealership's "GMC Truck Claims Processing Manual" #P 8719.
Dear GMC Truck Owner:
General Motors has determined that certain 1987 G35 model vans may have been produced with an engine compression ratio of 9.3:1 rather than 8.6:1 as intended. While there is an improvement in performance, this condition may result in spark knock.
To minimize the possibility of spark knock, the calibrator in your vehicle's Electronic Control Module (ECM) will be replaced. The new calibrator contains revised engine calibraton information which will allow your engine to operate properly at the increased compression ratio. The service will be performed at no charge to you.
Instructions for making this correction have been sent to your GMC Truck dealer. Please contact your GMC Truck dealer to arrange a mutually satisfactory service date. The labor time necessary to perform this service is approimately 30 minutes. Please ask your dealer if you wish to know how much additional time is needed to process your vehicle.
Should your dealer not schedule a service date within a reasonable time, you should contact your GMC Truck Zone Office by telephone for assistance. The telephone numbers of the Zone Offices are listed in your Owner's Manual.
The enclosed owner reply card identifies your vehicle. Presentaton of this card to your dealer will assist 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 so that we may update our records.
We are sorry to cause you this inconvenience; however, we have taken this acton in the interest of your confinued satisfaction with our products.
GMC TRUCK DIVISION GENERAL MOTORS CORPORATION
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.
