For 1990-2009 cars

# ECM/PROM INCOMPATIBILITY NEW SERVICE P/N RELEASED

#### MODELS AFFECTED: 1983-1984 BROUGHAM, DEVILLE (RWD), ELDORADO AND SEVILLE

A new ECM, service P/N 1226930, has been released to supersede service P/N 1226028 on all 1983-1984 HT4100-equipped vehicles. This new ECM will allow the PROM in all vehicles to be transferred to a service ECM without the possibility of the ECM-PROM incompatibility condition described in Serviceman Bulletin #T-84-30. The service procedures described in Bulletin T-84-30 are unnecessary when service P/N 1226930 is used.

Until the 1226930 ECM is available, continue to order P/N 1226028. This ECM will be automatically superseded by P/N 1226930 when it becomes available. The 1226028 ECM's in stock may continue to be used on all 1983-1984 vehicles, following the guidelines detailed in Bulletin T-84-30. The 1226028 ECM is of equal quality to the 1226930 ECM's; the purpose of the new ECM service part is to allow the ECM to be replaced without the possible need for a replacement PROM.

The guidelines from Bulletin T-84-30 pertaining to the 1226028 ECM are summarized below:

1983 Vehicles - 1226028 ECM may be used with no potential ECM-PROM incompatibility.

1984 Vehicles - 1226028 ECM may be used. If diagnostics are unusable after ECM is replaced, replace PROM with part number indicated in Bulletin T-84-30.

#### NOTE:1985 D/E/K Vehicles - 1226930 ECM is required. Do not use 1226028 (FWD-C vehicles use a different ECM which is specific to FWD-C only).

An ECM-PROM incompatibility will not result in damage to either the ECM or PROM. However, caution must be used in transferring PROM's to prevent physical damage to the PROM or ECM socket. Refer to Service Information Manual for proper PROM replacement procedure.

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.