Intermittent BCM Codes B446, B449, and B450

Bulletin No.: T-93-7
File in Group: 1
Number: 90
Corp.Ref.No.: 216203R
Date: Oct. 1992

SUBJECT:
INTERMITTENT BCM CODES - (INSTALL NEW BCM SERVICE PROM)
B446 - LOW A/C REFRIGERANT
B449 - A/C HIGH SIDE OVERHEATED, A/C OFF
B450 - ENGINE OVERHEAT, A/C OFF

MODELS AFFECTED:
1993 ALLANTES

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

B446 - "Low A/C Refrigerant" may be intermittently displayed during mild ambient (45~F to 65~F) 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 PROM 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 BAYY 7236 P/N 16185967 BCXW 4146
P/N 16177283 BAYY 7236 P/N 16185968 BCXW 4146

This new service PROM also contrains 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 A/C blower motor is increased from 4 V to 4.5 V to increase air flow at low blower speed.

Parts are currently available from GMSPO.

For warranty purposes use Labor Operation N4801 for .8 hour.