MOAN OR WHINE NOISE W/HEATED WINDSHIELD OPERATION

SUBJECT: MOAN OR WHINE NOISE WITH HEATED WINDSHIELD SYSTEM OPERATING (REPLACE POWER MODULE)

VEHICLES AFFECTED: 1992 "E AND K" MODELS

Some 1992 Eldorados and Sevilles may exhibit an audible moan or whine noise at idle, when in drive or reverse gear at low speeds, and the heated windshield system is on. The noise may be due to the heated windshield power module, which is mounted to the cross-car brace under hood. Refer to Figure 1.

When the system is operational, the power module converts alternating current from the alternator to direct current for the windshield. The noise may occur due to transformer vibrations inside the power module, transmitting through the brace into the shock towers.

Some noise is considered normal due to system operation changes for 1992 Eldorados and Sevilles.

o The 1991 Eldorado/Seville system used the BCM to disable system operation in drive at low speeds, to prevent transformer noise.

o The 1992 Eldorado/Seville added insulators (see Figure 1, 8) to the power module bracket, and changed moding to allow operation in gears and at all speeds. This improves effectiveness in deicing the windshield in low speed traffic conditions.

If a noise complaint is encountered, check the power module bracket insulators. Refer to Figure 1, 8. If the insulators are out of position, the module could be contacting the bracket and could transmit more noise than normal through the cross-car brace. Loosen the power module bracket bolts, refer to Figure 1 and position the insulators so the groove fits in the power module bracket holes. Torque the bolts to 6 N.m (4.5 ft. lbs.).

Also check and repair wiring or air conditioning pipes which may be contacting the power module mounting bracket.

For more information on heated windshield system operation and diagnosis refer to the Service Information Manual, Section 9N.

For vehicles being repaired under warranty use: labour - .2 hour.

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.