REAR WHEEL(S) SQUEAKY; SQUEAL SCRAPE NOISE-SERVICE PROCEDURE

VEHICLES AFFECTED: 1990 M/L WITH 4WAL BRAKES

Some customers may comment of squealing or scraping sounds generated near the rear wheel(s) which may be exhibited only on turns. This condition can be caused by one or both of the rear wheel sensor reluctors contacting the tone wheel(s).

The rear wheel sensors are not adjustable, however a technician might achieve sufficient clearance between the sensor and the tone wheel to eliminate this condition by loosening the wheel sensor mounting bolts, lightly prying the sensor away from the tone wheel with a small screwdriver to remove any slack, and then re-tightening the bolts to 35 Nm (26 ft.lbs.).

If this is not effective the sensor must be replace.

IMPORTANT: Light contact of the sensor reluctor to the tone wheel should not affect the durability of the tone wheel, and the tone wheel should not require replacement.

Service Procedure: (Refer to Fig. 1.)

1. Remove rear wheel and tire assembly.

2. Remove brake drum.

3. Remove primary brake shoe. Refer to Hydraulic Foundation Brakes (Section 5A2 of Service Manual X-9030).

4. Loosen sensor mounting bolts (2).

With a SMALL screwdriver very lightly pry the sensor outward, away from the tone wheel, to remove any slack.

Tighten the mounting bolts to 35 Nm (26ft. lbs.).

Install primary brake shoe. Refer to Hydraulic foundation brakes (section 5A2 of Service Manual X-9030).

Install brake drum.

Install wheel and tire assembly.

Road test vehicle to verify noise is eliminated.

If repair is successful skip steps 5 through 16.

5. If road test determines that the repair was not successful repeat steps 1-3.

6. Disconnect sensor wire electrical connector.

7. Disconnect sensor wire from the rear axle clips.

8. Remove sensor mounting bolts.

9. Remove speed sensor by pulling the wire through the hole in the backing plate.

10. Install new speed sensor (P/N #15649151-left rear sensor P/N #15649152-right rear sensor) and mounting bolts. Torque bolts to 35 Nm (26 ft. lbs.).

11. Install sensor wire to the rear axle clips.

12. Connect sensor wire electrical connector.

13. Install primary brake shoe. Refer to Hydraulic foundation brakes (Section 5A2 of Service Manual X-9030.

14. Install brake drum.

15. Install wheel and tire assembly.

16. Road test vehicle to verify noise is eliminated.

SERVICE PARTS INFORMATION

Part Number Description Quantity Model

15649151 Left rear wheel 1 M/L speed sensor

15649152 Right rear wheel 1 M/L speed sensor

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.