CAMPAIGN: FOUR SPEED MANUAL TRANSMISSION LOCKS IN REVERSE

MODELS: 1988 C/K 15-35 SIERRA TRUCKS EQUIPPED WITH 4-SPEED MANUAL TRANSMISSION (RPO MM4)

General Motors has determined that the transmission and transmission shift lever in some 1988 GMC C/K 15-35 Sierra Trucks equipped with 4-speed manual transmission (RPO MM4) could remain locked in the reverse position, due to the shift lever finger not adequately being retained in the reverse gate. When the shift lever finger slips out of the reverse gate, the shift lever can be moved very little from this location. It is apparent to a driver that the transmission is in reverse, because the lever is close to the normal reverse location. To correct this condition, it will be necessary to replace the transmission cover assembly in all involved vehicles.

VEHICLES INVOLVED

Involved are certain 1988 GMC C/K 15-35 Sierra Trucks equipped with 4-speed manual transmission (RPO MM4) built within the following VIN breakpoints:

Model Year Model Plant From Through ---- ----- ----- ---- ------- 1988 C/K 15-35 Pontiac East SSV JE501630 Fort Wayne SSV JZ500614 Oshawa SSV J1503799

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

Refer to Service Manual X-8731 Section 4, Propeller Shaft & Axles, and Section 7, Transmission and Clutch for further removal and installation instructions.

4-WHEEL DRIVE

o Place transfer case in 4H. o Disconnect negative battery cable. o Unclip and remove shift lever boot from console. o Remove shift lever assembly from transmission. o Remove console. o Lift and support vehicle. o Remove transfer case skid plate if equipped. o Drain lubricant from transfer case and transmission. o Disconnect transfer case shift control linkage. o Disconnect wiring harness and vent hose from transfer case. o Disconnect front propshaft at transfer case flange. - Reference mark the relationship of the propshaft at the flange. o Remove rear propshaft. o Remove transfer case to transmission adapter bolts. o Remove transfer case. o Disconnect wiring harness from transmission. o Remove transmission mount to crossmember nuts. o Support and raise transmission with an appropriate jack. o Remove crossmember. o Remove transmission to clutch housing bolts. o Remove transmission and place on a bench. - Before removing cover assembly from transmission ensure that all forward gears are in neutral and reverse is halfway engaged. o Remove and discard transmission cover. Clean case of all gasket material. o Place new cover assembly halfway in reverse, Figure No. 1, and install new gasket and cover assembly to transmission. Torque bolts 34 Nm (25 lb ft). o Reinstall transmission in vehicle. Transmission should be in reverse gear. Torque transmission to clutch housing bolts to 100 Nm (74 lb ft). o Reinstall crossmember. Torque mounting bolts to 75 Nm (55 lb ft). o Torque transmission mount to crossmember nuts to 47 Nm (35 lb ft). o Reconnect wiring harness to transmission. o Reinstall transfer case to transmission dapter utilizing a new gasket. Torque abolts to 33 Nm (24 lb ft). o Reconnect front propshaft. Torque flange bolts to 100 Nm (74 lb ft). o Reconnect vent hose and wiring harness to transfer case. o Reconnect transfer case linkage. o Reinstall skid plate if previously removed. o Refill transfer case with Dexron(R) II Auto-matic Transmission Fluid part number 1051855 (approx. 1.2 quarts). o Refill transmission with SAE-80W GL5 or SAE-80W-90 GL5 gear lubricant part number 1052271 (approx. 4.2 quarts). o Lower vehicle. o Replace console, shift lever assembly, shift lever boot, etc. o Reconnect the battery.

2-WHEEL DRIVE

o Disconnect negative battery cable. o Unclip and remove shift lever boot from console. o Remove shift lever assembly from transmission. o Remove console. o Raise and support vehicle. o Drain lubricant from transmission. o Disconnect wiring harness from transmission. o Disconnect propshaft from transmission. Loosen hanger bearing and tie shaft away from work area. o Remove transmission mount to crossmember nut. o Support transmission. o Remove transmission bolts at clutch housing. o Remove crossmember. o Remove transmission and place on a bench. - Before removing cover assembly from transmission ensure that all forward gears are in neutral and reverse is halfway engaged. o Remove and discard transmission cover. Clean case of all gasket material. o Place new cover assembly halfway in reverse, Figure No. 1, and install new gasket and cover assembly to transmission. Torque bolts 34 Nm (25 lb ft). o Reinstall transmission in vehicle. Transmission should be in reverse gear. Torque transmission to clutch housing bolts to 100 Nm (74 lb ft). o Reinstall crossmember. Torque mounting bolts to 75 Nm (55 lb ft). o Torque transmission mount to crossmember nut 54 Nm (40 lb ft.). o Reconnect wiring harness. o Reconnect propshaft to yoke. Torque bolts to 20 Nm (15 lb ft). Torque center bearing bracket bolts to 34 Nm (25 lb ft). o Fill transmission with SAE-80W GL5 or SAE-80W-90 GL5 gear lubricant part number 1052271 (approx. 4.2 quarts). o Lower vehicle. o Replace console, shift lever assembly, shift lever boot, etc. o Reconnect the battery.

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 under an advise code (2).

Part Number Description Quantity ----------- ----------- -------- 8672020 Transmission Cover 1 Assembly 14020854 Gasket - Transfer 1 Case to Adapter 15594369 Gasket - 1 Transmission Cover 1051855 Dexron (R) II Fluid 1.2 qts 1052271 SAE-80W GL5 or 4.2 qts SAE-80W-90 Gear Lube

WARRANTY INFORMATION

Dealers should submit a warranty claim on each vehicle completed under this campaign.

Labor Operation *Time Trouble Number Description Allowance Code ------------------------------------------------ Replace transmission cover assembly V4130 C Model 1.4hr 96 V4131 K Model 2.lhr 96

* Add 0.1 hours for administrative time allowance.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Builetin will require a "Campaign Identification Label". Each label provides a space to include the five (5) digit dealer code of the deater performing the campaign service. This information 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" #P8719.

Dear GMC Truck Owner:

General Motors has determined that certain 1988 GMC C/K 15-35 Sierra Trucks equipped with 4-speed manual transmission may have been built with a transmission and transmission shift lever which could remain in reverse after being put in that gear.

To correct this condition on your vehicle, please contact your GMC Truck dealer to arrange for a service date to have the transmission cover assembly in your truck replaced. This service will be completed at no charge to you.

Instructions for performing this service have been sent to your GMC Truck dealer. It is estimated that parts will be available to your dealer an September 1, 1987. The labor ume necessary to replace the transmission cover assembly in your vehicle will vary from 1-1/2 hours to 2 hours. Please ask your dealer if you wish to know how much additional time will be needed to process your vehicle.

The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer wih 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.

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