CAMPAIGN: AUTOMATIC TRANS FLUID LEAK

Models: 1988-93 C/K Models Equipped with 5.OL, 5.7L, 7.4L Engines and 4L60, 4L60-E and 3L80 Automatic Transmissions

TO: ALL GENERAL MOTORS DEALERS

General Motors of Canada Limited has determined that a defect which relates to motor vehicle safety exists in certain 1988-93 C/K Models equipped with certain combinations of 5.OL, 5.7L, 7.4L, engines and 4L60, 4L60-E and 3L80 automatic transmissions. The transmission fluid in these vehicles, as a result of unanticipated heat generation in the transmission, may be forced out of the vent tube. The heat generation is usually the result of trailering heavy loads at high speeds or high-load/off road use. If the vented transmission fluid comes in contact with the catalytic converter, ignition of the transmission fluid may result.

To prevent the possibility of this condition occurring, dealers are to install a longer transmission vent hose routed to the left side of the vehicle.

Owners are also being provided updated information on towing or off-road use with an overdrive equipped automatic transmission.

VEHICLES INVOLVED:

Involved are the models listed below built within the VIN breakpoints listed below:

Models Involved:

- 1988-93 C/K 1,2 model trucks equipped with 5.7L (LO5) engines and 4L60/4L60-E (MD8/M30) automatic transmission

- 1988-93 C/K 2 model trucks equipped with 5.OL (LO3) engines and 4L60/4L60-E (MD8/M30) automatic transmission

- 1988-90 C/K 2,3 equipped with 5.7L (LO5) or 7.4L engines and 3L80 (M40) automatic Transmission

VIN Breakpoints:

Year Model Plant From Through 1988-93 GMC Ft. Wayne (Z) SOP PZ500481 1988-93 Chevrolet Ft. Wayne (Z) SOP PZ101130 1988-93 GMC Oshawa (1) SOP P1502478 1988-93 Chevrolet Oshawa (1) SOP P1106823 1988-93 GMC Pontiac (E) SOP PE500573 1988-93 Chevrolet Pontiac (E) SOP PE102050 1992 GMC Janesville (J) SOP EOP 1992 Chevrolet Janesville (J) SOP EOP

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:

All unsold new vehicles in dealer's possession and subject to this campaign must be held and inspected/repaired per the Service Procedure of this Campaign Bulletin before owners take possession of these vehicles.

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

Owners of vehicles recently sold from your new vehicle inventory with no owner information indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make the required correction according to instructions contained in this bulletin. This could be done by mailing to such owners a copy of the owner letter accompanying this bulletin. Campaign follow-up cards should not be used for this purpose, since the owner may not as yet have received the notification letter.

In summary, whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or is in your dealership for service in the future, please take the steps necessary to be sure the campaign correction has been made before selling or releasing the vehicle.

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 (see copy of owner letter included with this bulletin). 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 15960319 Hose, Transmission Vent 1 11501906 Strap 1

PARTS AND LABOR 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 2A Install Transmission Vent Hose 0.3

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. Inspect vehicle for presence of lock-seal dipstick (Figure 1) as installed in Campaign 2D20 and 2D21, dated October 1992. If this lock-seal dipstick is not present it should be obtained through GMSPO and Campaign 2D20 or 2D21 completed. 2. Raise vehicle on hoist. 3. Inspect existing transmission vent tube (Figure 2) to be certain it is not plugged with dirt or debris and clean if necessary. IMPORTANT: It is important that this vent tube is open. If this tube is plugged, premature transmission seal failure may result. 4. Lube the inner diameter of the vent hose with a small amount of clean transmission fluid and install it over the existing vent tube until secure. IMPORTANT: This vent hose is constructed of fuel line rated material. The use of any other type hose is discouraged as it may deteriorate in this application.

5. Locate the vent hose as shown in Figure 2 and secure it to the transmission wiring harness with the tie strap.

6. 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.

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.