Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Intermittent BCM Codes B446, B449, and B450
1993 Cadillac Allante V8-281 4.6LSECTION 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.
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.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.