CALPAC INSTALLATION-ENGINE START/NO RUN INFORMATION

VEHICLES AFFECTED: All 1984 'J' Series

All 1984 'J' Models use a new type of Electronic Control Module. This ECM uses a PROM and a device called a CALPAC. The purpose of the CALPAC is to allow fuel delivery in the event of PROM or ECM malfunction. The CALPAC has an access door in the ECM, and removal and replacement procedures are the same as with the PROM.

Anytime an ECM replacement is required on a 1984 'J' Model, both the PROM and CALPAC must be removed from the replaced ECM and installed into the replacement ECM. If the CALPAC is left out, the engine will crank but will not run.

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.