K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Technical Service Bulletin # 918C51
Date: 901201
Odometer - Ceases to Record Mileage
GMC NUMBER: 91-8C-51
GROUP: 8C Instrument Panel and Gages
DATE: December, 1990
CORPORATE
NUMBER:068301R
SUBJECT: ODOMETER SEIZURE DUE TO DUST INTRUSION
MODELS: 1988-91 C/K LIGHT DUTY TRUCKS
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Important
This bulletin does not apply to 1991 C/K trucks with RPO U16 (Cluster with Tachometer)
Some 1988 through 1991 C/K trucks may experience an odometer seizure (the odometer ceases to record mileage).
This condition is usually caused by dust intrusion through the vent holes on the instrument cluster. The condition is experienced mainly in (but not
limited to) dry, dusty areas, farms, and mining environments.
If this condition is found, the odometer should be replaced. In addition, the vent holes on the instrument cluster should be taped over to prevent
further intrusion of dust. The following procedure should be used when performing the replacement.
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Important
When replacing the odometer, the mileage on the new odometer must be set to the same mileage as the current odometer on the vehicle. It is against the
law and against GM procedures to do otherwise.
Service Procedure
Removal Of Cluster
NOTICE: Be sure to follow ESD (Electrostatic Discharge) Sensitive procedures listed here and in Section 8C of the Service Manual when performing
this procedure. Failure to do so could result in damage to the instrument cluster assembly. Any time an instrument cluster is handled:
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the technician should wear a wrist strap and ground lead.
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the instrument cluster should be transported to and from the vehicle in an ESD handling bag.
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the work area floor should be covered by an approved, grounded floor mat. Painting the work area with conductive paint is not an approved
alternative.
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the work area must be free of static producing items such as styrofoam, plastic, carpet, etc.
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clothing worn should have a high cotton content. Following these precautions will help protect sensitive electronic components.
1. Disconnect the battery ground cable.
2. Disconnect and remove the radio and heater control units. Refer to the ACCESSORIES (SEC. 9) and HEATING AND VENTILATION
(SEC. 1A) sections of the Service Manual.
3. If the vehicle has an automatic transmission, remove the PRNDL indicator cable.
4. Remove the four retainer screws holding the cluster assembly to the instrument panel.
5. Pull out the instrument cluster and remove it from the vehicle. Keep fingers and other foreign objects away from the circuit board pins.
Removal of Odometer
