Interior - Moan or Whine w/ Heated Windshield Operating

91cadillac11

Bulletin No.: T-92-23
File in Group: 9
Number: 82
Corp. Ref. No.: 119013R
Date: Nov. 1991


SUBJECT: MOAN OR WHINE NOISE WITH HEATED WINDSHIELD
SYSTEM OPERATING


MODELS AFFECTED: 1992 ELDORADOS AND SEVILLES

Figure 1:

Some 1992 Eldorados and Sevilles may exhibit an audible moan or whine noise at idle, in drive or reverse gear at low speeds, when 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.

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

^ 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 (see Figure 1, 1) and position the insulators so the groove fits in the power module bracket holes. Torque the bolts to 6 N-m (4.5 lbs.ft.).

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 warranty purposes use Labor Operation T6567, Inspect/Repair Heated Windshield Power Module Mounting, at .2 hour.