CAMPAIGN: COLD DRIVEABILITY NEW MEM-CAL (SYCLONE). GMC Truck S15 Pickup - 4WD 1991

For 1990-2009 cars

# CAMPAIGN: COLD DRIVEABILITY NEW MEM-CAL (SYCLONE)

#### SUBJECT: IDLE SURGE / HESITATION DURING COLD START

#### MODELS: 1991 "T1 " GMC SYCLONE (SHREVEPORT ASSEMBLY PLANT)

PAS, Inc., the final stage manufacturer of the 1991 Syclone, in consultation with General Motors, has determined that on certain 1991 GMC Syclone trucks the Memory and Calibration units (MEM-CALs) were not optimally calibrated, resulting in an idle surge and/or hesitation condition during a "cold" engine start.

To correct this, the MEM-CAL calibration on GMC Syclones has been changed.

#### VEHICLES INVOLVED

Involved are CERTAIN 1991 GMC Syclones BUILT BEFORE the following VIN:

Model Model Year Plant From Through ----- ----- ---------- ----- --------- GMC 1991 Shreveport SOP M8801522

Some vehicles built before the above VIN were built with the new MEM-CAL. Those vehicles will have the following information handwritten on the white ECM bar code label.

MEM-CAL P/N 16163961 - Broadcast AYBM Updated (date).

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. 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 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 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.

#### SERVICE PROCEDURE

1. Disconnect negative battery cable. 2. Disconnect connectors from ECM. 3. Disconnect ECM mounting hardware. 4. Remove ECM from passenger compartment. 5. Remove ECM access cover (Figure 1). 6. Using two fingers, push both retaining clips back away from the MEM-CAL. At the same time, grasp the MEM-CAL at both ends and lift it up out of the socket. Do not remove the cover of the MEM-CAL. Use of unapproved MEM-CAL removal methods may cause damage to the MEM-CAL or socket (Figure 2). 7. Install new MEM-CAL in MEM-CAL socket.

#### Important

Press only on the ends of the MEM-CAL. Small notches in the MEM-CAL must be aligned with the small notches in the MEM-CAL socket. Press on the ends of the MEM-CAL, until the retaining clips snap into the ends of the MEM-CAL. Do not press on the middle of the MEM-CAL, only the ends.

8. Install the access cover on ECM. 9. Write the following on the white ECM bar code label. MEM-CAL part number 16164052

10. Install the ECM in the passenger compartment.

#### Important

When installing the ECM into the passenger compartment position the wire out of the top (green) connector (see item 1 Figure 3) between the connector thumb latch and the tab on grey comb.

Place tape as shown (item 2 Figure 3) to retain wire in this position during ECM installation. To avoid interference, it will be necessary to move the cross body power door lock harness as shown prior to ECM installation (see Item 3 Figure 3).

11. Apply the supplied tamper proof sticker over the access cover of ECM.

#### Important

Record the new PAS ECM tamper resistant label registration number on the front of the repair order as part of the write up.

12. Install the connectors to ECM. 13. Install the "Campaign Identification Label". 14. Install the negative battery cable.

#### PARTS INFORMATION

Parts required to complete this campaign will be shipped to involved dealers by GMC Truck on a no charge basis. Any questions pertaining to parts shortages, etc., should be directed to Adistra Corporation (313) 455-9072.

DO NOT ORDER PARTS FOR THIS CAMPAIGN FROM GENERAL MOTORS SERVICE PARTS OPERATION (GMSPO).

Part Quantity/ Number Description Vehicle --------- -------------- --------- 16164052 MEM-CAL 1

NPN Tamper Proof Sticker 1

#### WARRANTY INFORMATION

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

Labor Oper. *Time **Parts Trouble Number Description Allowance Allowance Code ------ ----------- -------- --------- ---- V6840 MEM-CAL 0.8 hr. $6.90 96 Replace

* For dealer to receive Administrative Time Allowance associated with this campaign, add 0.1 hour to the Labor Operation Time Allowance.

** The amount identified in the "Parts Allowance" column above represents 30% of dealer net for parts that are furnished in this campaign. This amount is to be placed in the Net Item Amount column of the claim and type Code "M".

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 "GM Truck Claims Processing Manual" #P9119.

Dear GMC Sycione Owner:

Our records show that you own one of our new 1991 GMC Syclone trucks. The rate at which these trucks have been accepted into the stream of commerce has been very gratifying to us. In addition, feedback from customers, dealers and our own tracking systems indicate a very high degree of product reliability thus far.

We have recently become aware of a situation on certain 1991 early production Syclones that may affect the "cold start" performance of your truck. The Memory and Calibration unit (MEM-CAL) on your truck was not optimally calibrated, and may result in a condition described as idle variation during a "cold" engine start.

In the interest of maintaining your satisfaction with our product, we would like to correct this condition by replacing the MEM-CAL at no charge to you.

At your convenience, please contact your GMC Truck dealer to arrange a service date. Instructions for making this correction have been sent to your dealer. Please ask your dealer if you wish to know how much time will be needed to schedule, process and repair your vehicle. 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. We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction.

#### SAMPLE LETTER WHICH IS BEING MAILED TO NON-INVOLVED OWNERS

Dear GMC Syclone Owner:

You may have heard recently about a GMC Syclone "Recall" and we want to let you know what this is all about . . . and especially to let you know that your GMC Syclone is not involved.

Recently we became aware of a situation on certain 1991 early production Syclones that may affect the "cold start" performance. The Memory and Calibration unit (MEM-CAL) on some trucks was not optimally calibrated and could result in a condition described as idle variation during a "cold" engine start.

Our records show that your truck has a correctly calibrated MEM-CAL and will, therefore, NOT be affected by this condition. Since GMC Truck will be correcting this condition at no charge to owners of affected vehicles, this letter is also being sent to you to provide assurance that your vehicle is not involved and will, therefore, not require correction.

We have taken this action in the interest of your continued satisfaction with our products and services. Thank you for choosing to buy a GMC truck.

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.