BRAKE SERVICE LIGHT/ABS LIGHT COMES ON (FALSE CODE 83)

Subject: BRAKE SERVICE LIGHT/ANTI-LOCK BRAKE SYSTEM (ABS) LIGHT COMES ON, FALSE CODE 83

Model and Year: 1992-93 CORVETTE

CONDITION:

--------- Brake service light (red) and ABS light (amber) come on and fault code "83" (low fluid) is stored.

CAUSE:

----- At lower fluid levels (due to partial lining wear), the brake fluid level sensor introduced on the 1992 Corvette may be overly sensitive during severe braking and/or handling maneuvers.

CORRECTION:

---------- To correct this condition, revisions were made to the fluid reservoir to reduce sensitivity to fluid movements during dynamic braking and turning conditions at lower fluid levels with partial lining wear. This new reservoir went into production with VIN P5114078. On vehicles built prior to this, replace the existing brake fluid reservoir (Part 12509940) with the new reservoir (Part 12512995). Refer to Section 5A-7 in the 1992-93 Corvette Service Manual for replacing the reservoir. The 0-rings (Part 12509976) must also be replaced.

NOTE: The brakes "DO NOT" have to be bled. After reinstalling the reservoir, plug the prime pipe nipple and refill the reservoir with new fluid. Carefully pour some fluid into the prime pipe until it is full and then remove the plug from the nipple and reinstall the prime pipe after allowing some fluid to run from the nipple. This will insure that no air is left in the system.

Remove the stored Code 83 from the history memory of the ABS controller.

In all cases where the fluid level is low due to worn linings, the brake service lamps will illuminate and fault code "83" will be stored. To correct this condition, the brake linings will have to be replaced. Also, remove the stored code "83" from the history memory of the ABS controller.

In some cases the wrong components were replaced and/ or fluid was added to the reservoir to bring the fluid to the full level. On vehicles with worn brakes, the fluid level in the reservoir is low due to the normal lining wear. When replacing the reservoir and adding new fluid, the fluid level should closely match the level in the old reservoir. If the fluid is filled to the full mark with worn linings, the excess fluid will have to be removed to avoid overflowing when replacing the brake linings.

PART AVAILABILITY:

Parts are expected to be available on 6/21/93.

WARRANTY INFORMATION:

Labor Operation: H-2489

Use Existing Labor Times.

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.