A/C - Intermittent BCM Codes B446, B449, B450
Bulletin No.T-93-7AFile In Group: 1
Number: 90
Corp. Ref. No. 216203R
Date: July 1993
Subject:
Intermittent BCM Codes (install New BCM Service EPROM's)
B446 - Low A/C Refrigerant
B449 - A/C High Side Overheated, A/C Off
B450 - Engine Overheat, A/C Off
Models Affected:
1993 Allantes
This bulletin supersedes Service bulletin T-93-7 which should be discarded. This bulletin is being revised to clarify parts replacement procedure, add a NOTE, and change the warranty statement.
Some 1993 Allante's may intermittently exhibit the following BCM diagnostic codes:
B446 - "Low A/C Refrigerant" maybe 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.
B45O - "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 illustrated service EPROM's will correct calibrations for the B449 and B45O diagnostic codes and eliminate the B446 code.
NOTE:
To properly repair the above condition(s) both EPROM's must be replaced. The black EEPROM does not need to be replaced.
The new service EPROM's also contain adjustments to prevent the PCM snap shot 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 13447 or 13448 are detected. The minimum blower motor voltage 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 .7 hour.