CAMPAIGN: MASTER CYLINDER BRAKE PROPORTIONER SUPPLEMENT

This supplemental bulletin has been sent to give more information about the campaign parts being supplied for Campaign 83C15.

The suspect brake proportioner valves being replaced in Campaign 83C15 were used only on regular production 1983 Chevrolet Celebrity, Citation and Cavalier models. The only cars affected are those within the serial number breakpoints in product Campaign Bulletin 83C15 issued October, 1983.

NO SUSPECT VALVES WERE SUPPLIED AS SERVICE PARTS. NO SUSPECT VALVES WERE SUPPLIED AS CAMPAIGN PARTS.

A quantity of known good proportioner valves with the same machine marks as those being replaced, but with date codes higher than the suspect range, were used to provide campaign parts. Use of valves that look the same as those being replaced has caused confusion at some dealerships.

To eliminate this confusion, and to avoid unnecessary replacement of good valves in the future, the following is recommended:

Use any service parts which may be in stock. They are all good valves.

Valves received in campaign parts packages, regardless of their machine marks, are okay. Use them on campaign cars as needed.

Be sure to install campaign identification labels in each car serviced, to avoid unnecessary future replacement of good valves.

Do not be concerned with the campaign service valves that you may have already installed. They are all good valves.

The following identification pictures are reprinted from Product Campaign Bulletin 83C15. The pictures represent the types of valves which were found on cars in this campaign only.

Suspect proportioner valves which are installed on cars to be campaigned can be identified as described in Figure 1, View A. In addition, the suspect valves will have six character Julian Date Codes stamped in the valve body from FJ, RJ, FK or RK 2305 through 3035. See Figure 2, below.

Valves with different machine marks than Figure 1, View A, are okay.

Valves with the same machine marks as View A, but date codes lower than 2305 or higher than 3035, are okay.

Valves received in service parts or campaign parts packages, regardless of their machine marks, are okay.

Valves on cars with serial numbers lower or higher than the serial number breakpoints in bulletin 83C15 are okay.

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.