CAMPAIGN:CRANKSHAFT POSITION SENSOR FAILURES

SUBJECT: CRANKSHAFT POSITION SENSOR FAILURES

MODELS: 1995 S/T TRUCKS WITH 4.3L ENGINES

General Motors has determined that CERTAIN 1995 GMC Truck 2 wheel and 4 wheel drive Sonoma pickup trucks equipped with 4.3L engines (RPO L35 - VIN Code "W") and 1995 GMC Truck 4 wheel drive Jimmys equipped with 4.3L engines (RPO L35 - VIN Code "W") and automatic transmission with Electronic Transfer Case (RPO NP1) were shipped with a crankshaft position sensor that may fail due to liquid intrusion. Failure of the sensor may result in engine stalling with a no start or hard start condition.

To correct this condition, dealers are to install a new crankshaft position sensor.

VEHICLES INVOLVED

Involved are CERTAIN 1995 S/T pickup trucks equipped with 4.3L engines (VIN Code "W") and 4 wheel drive Jimmys with 4.3L engine (VIN Code "W") and automatic transmission with Electronic Transfer Case (RPO NP1) built within the following VIN breakpoints:

Year Model Plant Code From Through

1995 S/T K SOP K528565 1995 S/T 2 SOP 2536426 1995 S/T 8 SOP 8526247

The specific vehicles involved in this campaign have been identified by Vehicle Identification Number (VIN) Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin. Dealers should confirm vehicle eligibility through VISS (Vehicle Information Service System)or SERVICENET prior to beginning campaign repairs.

DEALER CAMPAIGN RESPONSIBILITY

All unsold new vehicles in dealers' 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 service all vehicles subject to this campaign at no charge to owners, regardless of mileage, age of vehicle, or ownership, from this time forward. Dealers are to 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 ensure the campaign correction has been made before reselling or releasing the vehicle.

Owners of vehicles recently sold from your 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 the name and address of the owner of an involved vehicle was unavailable to GMC Truck Division at the time of campaign initiation, the dealer must 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.

PARTS INFORMATION

50% of parts required for this campaign will be preshipped to involved dealers of record. This preshipment will occur the week of May 1, 1995. Parts received for recently transferred vehicles should be forwarded by the original dealer (with an accompanying phone call) to the dealer that received the transferred vehicle.

Additional parts required to complete this campaign are to be obtained from General Motors Service Parts operation (GMSPO). To ensure parts are obtained as soon as possible, order them from GMSPO on a C.I.O. order with no special instruction code but order under an advise code (2). All Goodwrench Parts System test dealers should order on a "VIP" order.

Part Number Description Quantity ----------- ------------ -------- 10456292 Sensor Assembly - Crankshaft Position 1

SERVICE PROCEDURE

1. Disconnect the Intake Air Temperature (IAT) sensor electrical connector. Loosen the throttle body hose clamp and remove the retainers from the air duct/air cleaner assembly. Move aside the air duct/air cleaner assembly as one unit.

2. Disconnect the crankshaft position sensor from the engine wiring harness. Cut the electrical connector off the crankshaft sensor assembly and remove harness from vehicle.

3. Raise the vehicle.

4. On 4WD vehicles only - Remove the front axle under body shield (steering linkage shield).

5. Remove the crankshaft position sensor retaining bolt and sensor from the engine front cover (Figure 1, Item 1).

6. Cut and discard the lower plastic harness retainer (rosebud) at the front cover bracket, remove the crankshaft position sensor assembly from the vehicle.

7. Carefully route the new crankshaft position sensor harness (Figure 1, Item 2) (connector end) up between the water pump and engine block/front cover on the right (passenger) side of the engine. The retaining clip on the harness electrical connector (Figure 1, Item 3) should be facing the front of the vehicle as it is moved up into position.

NOTICE: DO NOT use excessive force which may damage the connector and/or harness. The use of a "Pick-Up Tool", (such as Snap On's YA837 or equivalent), to hold the connector, and a long narrow screwdriver to move and position the connector and harness will prove useful.

8. Install the crankshaft position sensor in the engine front cover. Check to see that the sensor is fully seated in the front cover prior to torquing down the retaining bolt. Torque the crankshaft sensor retaining bolt to 7-9 Nm (62-80 lbs in). USING HAND TOOLS ONLY, DO NOT EXCEED TORQUE SPECIFICATION. Install the new plastic harness retainer (rosebud) to the engine front cover bracket. Check for sufficient clearance between the wiring harness and the harmonic balancer.

9. On 4WD vehicles only - Re-install the front axle under body shield, torque bolts to 32 Nm (283 lbs in).

10. Lower the vehicle.

11. Complete routing of the crankshaft position harness. The harness should be routed under the top heater hose and away from the EGR valve base.

NOTICE: DO NOT use excessive force that may damage the connector and/or harness. Use a long pick-up tool, (such as Snap On's YA837 or equivalent), attached to the connector retaining clip loop to raise the connector and position it properly. Connect the crankshaft position sensor harness to the engine wiring harness.

12. Reinstall the air duct/air cleaner assembly. Tighten the hose clamp and install the retainers. Connect the IAT sensor harness.

13. Start and run the engine one minute to verify correct engine operation (no Malfunction Indicator Lamp illumination).

14. Install Campaign Identification Label.

WARRANTY INFORMATION

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

Labor Operation *Time Net Cause Number Description Allowance Amount Code ---------------------------------------------------------------------------- V9590 Replace Sensor (2WD) 0.4 --- 96 V9591 Replace Sensor (4WD) 0.5 --- 96 T2460 Fuel Top-Off --- + 96 T2461 Wash Vehicle --- ++ 96

NOTE. LABOR OPERATIONS T2460 AND T2461 ARE TO BE PERFORMED ONLY ONCE FOR VEHICLES INVOLVED IN CAMPAIGN 95C31/95C33/95C34/95C35.

* For dealer to receive Administrative Time Allowance associated with this campaign, add 0. 1 hour to the Labor Operation Time Allowance.

+ The amount to be entered in the "Net Amount" column should represent the cost of the fuel required to fill the vehicle's tank for a customer. Note that the amount submitted should represent the self-service price of regular unleaded fuel.

++ The amount to be entered in the "Net Amount" column should represent the cost for a customer car wash up to $6.00.

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 campaign number and five (5) digit dealer code of the dealer 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 Warranty Claims Processing Manual" #P9119 Rev. 2/94.

Dear GMC Truck Owner:

General Motors has determined that CERTAIN 1995 GMC Truck Sonoma pickup trucks, and 4 wheel drive Jimmys equipped with a 4.3L engine may experience a condition in which the crankshaft position sensor improperly functions. This condition could lead to engine stalling with restarting difficult or impossible.

To correct this condition, your GMC Truck dealer will install a new crankshaft position sensor. This service will be completed for you at no charge.

Instructions for performing this service have been sent to your GMC Truck dealer, and parts are available. Please contact your GMC dealer to arrange a service date as soon as possible. This procedure will take approximately 30 minutes to complete, but you should ask how much additional time your dealer will need to schedule and process your vehicle.

Your GMC Truck dealer is best equipped to provide service to ensure your vehicle is corrected as promptly as possible. However, if you take your vehicle to your dealer on the agreed service date and they do not service this condition on that date or within five days, we recommend you contact GMC Truck Consumer Relations. Consumer Relations will assist you and your dealer in getting your vehicle corrected. The telephone number of the Consumer Relations office is listed in your Warranty and Owner Assistance Information Manual.

After contacting your GMC Truck dealer and GMC Truck Consumer Relations, if you are still not satisfied that we have done our best to remedy this condition without charge within a reasonable time, you may wish to write the Director, Manufacturers Operations Division (64 05 J), United States Environmental Protection Agency, 401 M Street, S.W., Washington, D.C. 20460. To ensure your full protection under the emission warranty made applicable to your vehicle by Federal Law, and your right to participate in future recalls, it is recommended that you have your vehicle serviced as soon as possible. Failure to do so could legally be determined to be lack of proper maintenance of your vehicle. Also, your vehicle may fail a state or local emission inspection test if the recall work is not accomplished.

Should your dealer find that your emission system has been intentionally disabled, you will be asked if you wish the system to be restored so that it will function as designed. The cost of such restoration will be your responsibility.

The enclosed postage paid owner reply card identifies your vehicle. Presentation 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 furnish us the complete name and address of the person you sold or traded your vehicle to and return the card to us.

IMPORTANT MESSAGE FOR CALIFORNIA RESIDENTS

The California Air Resources (CARB) requires that vehicle emission recall campaigns be completed prior to California registration renewal. Uncorrected emission recall campaigns will result in the inability to renew your California vehicle registration.

At the time of emission campaign completion, your California dealer will issue a "Campaign Certificate of Completion". Keep this certificate and, if required, present it to the Department of Motor Vehicles when renewing your California registration as proof of campaign completion.

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

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.