CAMPAIGN: ECM RESISTOR PRODUCT EMISSION-ECM EGR DIAG.RESISTOR

Subject: PRODUCT EMISSION CAMPAIGN 91C06 ELECTRONIC CONTROL MODULE (ECM) RESISTOR

Model and Year: 1991 GEO STORM (CALIFORNIA EMISSIONS ONLY)

TO: ALL CHEVROLET DEALERS

General Motors has determined that certain 1991 Geo Storm model vehicles may exhibit a condition in which the check engine light illuminates when engine coolant temperatures are below 68 degrees Fahrenheit. This condition is a result of an incorrect resistor in the Electronic Control Module's (ECM) Exhaust Gas Recirculation (EGR) diagnostic circuit.

To correct this condition, dealers are to install a new ECM in involved vehicles.

VEHICLES INVOLVED

Involved are certain 1991 Geo Storm model vehicles built within the following VIN breakpoints:

PLANT YEAR MODEL PLANT CODE FROM THROUGH ----- ----- ------- ---- -------- ------- 1991 R-Car Fujisawa 7 M7500057 M7524134

Involved vehicles have been identified by Vehicle Identification Number Computer Listings. Computer listings contain the complete Vehicle Identification Number, owner name and address data, and are furnished to involved dealers with the campaign bulletin. Owner name and address data furnished will enable dealers to follow-up with owners involved in this campaign.

These listings 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 the follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with the campaign bulletin has no involved vehicles currently assigned.

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of owner letter included with this 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 be sure 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.

PARTS INFORMATION

Parts required to complete this campaign are to be obtained from General Motors Service Parts Operations (GMSPO). To ensure 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 on an advise code (2). NOTE THAT THE INVOLVED VEHICLES ARE CALIFORNIA EMISSION EQUIPPED ONLY. PEDERAL EMISSION DEALERS DO NOT NEED TO ORDER STOCK PARTS FOR THIS CAMPAIGN.

Quantity/ Part Number Description Vehicle ---------- ------------------------ -------- 16161199 ECM - DOHC - Manual Trans. 1

16161269 " - DOHC - Auto Trans. 1

16161229 " - SOHC - Manual Trans. 1

16161179 " - SOHC - Auto Trans. 1

(DOHC = Dual Overhead Cam; SOHC = Single Overhead Cam)

REMOVED ECM'S ARE TO BE RETURNED TO GMSPO FOLLOWING REGULAR ECM RETURN PROCEDURES. HOWEVER, THE CORE INFORMATION TAG MUST INDICATE IF THE ECM CAME FROM A UNIT WHICH WAS A RESALE DELIVERY OR PROM A STOCK UNIT. ALSO, THE TAG SHOULD INDICATE THAT THE ECM WAS REPLACED UNDER PRODUCT EMISSION CAMPAIGN 91C06.

SERVICE PROCEDURE

1. Remove and replace current ECM with the appropriate new ECM referring to pages 6E3-Cl-6 through 6E3-Cl-7 of the 1991 Geo storm Service Manual. It is not necessary to perform the "EEPROM" reprogramming in this procedure. The ECMs being used in this campaign have been programmed at the factory and already contain the needed softvare calibrations.

2. Install Campaign Identification Label.

CAMPAIGN IDENTIFICATION LABE

Each vehicle corrected in accordance with the instructions outlined in this 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 information may be inserted with a typewriter or a 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.

CLAIM INFORMATION

Submit a Product Campaign Claim with the information indicated below:

FAILED PARTS CC-FC LABOR LAB OTH REPAIR PERFORMED PC PART NO. ALLOW OP HRS HRS ---------------------- --------- ------ ----- ---- --- --- Remove and Replace ECM 1 16161199 ** SK-00 V6480 0.4 0.1

Campaign Administrative Allowance.

The "Parts Allowance" should be the sum total of the current GMSPO Dealer Net price plus 30% of all parts required for the repair.

Dealers will automatically receive the correct labor and material allowance based on the labor operation performed.

Refer to the Chevrolet Claims Processing Manual for details on Product Campaign Claim Submission.

Dear Geo Storm owner:

This notice is sent to inf orm you that Chevrolet Motor Division is conducting an emission recall campaign that includes your vehicle.

REASON FOR THIS RECALL

General Motors has determined that your 1991 Geo Storm may exhibit a condition in which the check engine light illuminates when engine coolant temperatures are below 68 degrees Fahrenheit. This condition is a result of an incorrect resistor in the Electronic Control Module's (ECM) Exhaust Gas Recirculation (EGR) diagnostic circuit.

WHAT WE WILL DO

To correct this condition, your dealer will install a new ECM at no charge to you.

WHAT YOU SHOULD DO

Please contact your Chevrolet dealer as soon as possible to arrange a service date and so the dealer may order the necessary parts to perform the repair. Instructions for making this correction have been sent to your dealer. The labor time necessary to perform this service correction is approximately 20 minutes. Please ask your dealer if you wish to know how much additional time will be needed to schedule and process your vehicle.

The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction in the shortest possible time. If you have sold or traded your vehicle, please let us know by completing the postage paid reply card and returning it to us. Should your dealer not schedule a service date within a reasonable time, you should contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020. If your dealer and the Customer Assistance Center are unable to remedy this condition within a reasonable time, you may wish to advise the Environmental Protection Agency, at the following address: Director, Manufacturer's operations Division (EN-340F), 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 this recall work is not accomplished.

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

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.