INTERMIT BCM CODES B446/B449/B450 (INSTALL BCM SERV. PROM)

SUBJECT: INTERMITTENT BCM CODES B446, B449 AND B450 (INSTALL NEW BCM SERVICE PROM)

VEHICLES AFFECTED: 1993 "V" MODELS

THIS BULLETIN SUPERSEDES AND REPLACES CORPORATE BULLETIN REFERENCE NUMBER 216203.** THIS BULLETIN IS BEING REVISED TO CLARIFY PARTS REPLACEMENT PROCEDURE, ADD A NOTE, AND CHANGE THE WARRANTY STATEMENT.

Some 1993 Allantes may intermittently exhibit the following BCM diagnostic codes:

B446 - "Low A/C Refrigerant" may be intermittently displayed during mild ambient (45 degrees Fahrenheit to 65 degrees Fahrenheit) temperatures.

B449 - "A/C High Side Overheated, A/C Off " may be displayed during high ambient temperatures when vehicle is idled for several minutes.

B450 - " Engine Overheat, A/C Off " may be displayed during high ambient temperatures when vehicle is at idle or driven at very low speeds for extended periods of time.

The following service EPROM will correct calibrations for the B449 and B450 diagnostic codes and eliminate the B446 code:

Broadcast Broadcast Old PROM's Code I.D. New PROMS Code I.D. ---------------------------------------------------------------------------

P/N 16177286 (RED) BAYY 7236 P/N 16185967 BCXW 4146 P/N 16177283 (GRAY) BAYY 7236 P/N 16185968 BCXW 4146

This new service EPROM also contains adjustments to prevent the PCM snapshot mode display of P000 and corrections to the program which may prevent the display of "Very Low A/C Refrigerant, A/C Off " when diagnostic codes B447 or B448 are detected. The minimum blower motor voltage is increased from 4 V to 4.5 V to increase air flow at low blower speed.

For vehicles repaired under warranty use:

Labour Operation: N4801 Labour Time: .7 hours

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.