Exterior Lighting - Short Bulb Life
90cadillac12Bulletin No. T-91-12
File in Group 8
Number 124
Corp. Ref. No. 918201R
Date Oct. 1990
SUBJECT: REDUCED BULB LIFE
MODELS AFFECTED: 1987-1989 ALLANTES
This bulletin supersedes Service bulletin T-89-127 which should be discarded. This bulletin has been revised to add information about a new regulator.
Some 1987-1989 Allantes may experience a condition of reduced bulb life. This condition may be caused by poor bulb quality or high system voltage. The exterior lighting system of the Allante operates at a higher voltage than most other vehicles. For this reason quality of the bulbs used for service is extremely important.
Rear Stop/Turn Bulbs:
The rear stop/turn bulbs are standard # 2057 dual filament bulbs. These bulbs should be procured only from top quality, well-known manufacturers.
One specific source of rear stop and turn bulbs has been identified which could cause significantly shortened bulb life on the Allante. These bulbs are characterized by a silver colored base (most bulbs have brass colored bases). The designation "PL2057" is stamped in the base. Bulbs fitting this description should not be used in the Allante. This bulb may not withstand the high operating temperatures caused by the high lamp voltage in the Allante.
The "silver base PL 2057" bulb is one of many # 2057 bulbs available from GM Service Parts Operations under P/N 9438848. These bulbs are OK to use on any GM model except Cadillac Allante.
Center High Mounted Stop Lamp Bulb:
Recent analysis has indicated that some dealerships may be using an incorrect bulb to service the center high mounted stop lamp on 1987-1989 Allante models. The correct bulb for this application is trade number 892. The part number is 9442048, parts group 8.991, which is currently available from GMSPO.
Lower Output Voltage Regulator:
If the correct bulbs are being used and shortened bulb life still occurs, install the 1990 generator voltage regulator, P/N 1116434, as outlined in the appropriate Service Information Manual. This regulator lowers system voltage by .5 volts and thus lengthens bulb life.
IMPORTANT: This does not apply to 1990 Allantes. All 1990 Allantes are already equipped with P/N 1116434 regulator.
Make sure the vehicle battery is fully charged before returning the car to the customer. The battery test indicator should be green.
Parts are currently available from GMSPO.