ECM - Plug In PROM and CALPAC

Bulletin 84-6c-2

Date NOV. 1983

Ref. No. 84-026-6

Subject: PORT FUEL INJECTION ELECTRONIC FUEL INJECTION

MODELS AFFECTED: ALL 1984 3.8L MFI & SFI AND 2.0L EFI EQUIPPED VEHICLES

The all new ECM used on 3.8L, Buick MFI and SFI engines uses a plug in Prom and Calpac. In appearance the Prom, is basically the same that has been used on CCC and EFI vehicles in the past. The second plug-in module used in this ECM is called a Calpac and is smaller than the Prom. The Calpac is programmed to take over basic fuel and spark control functions in the event of an ECM or Prom failure. Stated simply it allows continued engine operation in the back-up mode.

Anytime an ECM replacement is required on a Buick 3.8L MFI or SFI or a 2.0L EFI engine both the Prom and Calpac must be removed from the replaced ECM and installed into the replacement ECM.

PROM & CALPAC LOCATIONS:

See illustrations for location of Prom and Calpac.

Note: ^ If the Calpac is left out of the 3.8L Buick engines, the engine will start and run, however a solid "service engine soon" lamp will appear along with a code 52 (missing Calpac) will be stored.

^ If the Calpac is left out of a 2.0L EFI engine, the engine will crank but will not run. It will not provide a "service engine soon" lamp and will not store code 52.