Non-Factory Hydraulic Parking Brakes

91chevy20

GMC NUMBER: 91-5-101

GROUP: 5 Brakes

DATE: June, 1991

CORPORATE
NUMBER: 165006


SUBJECT: NON-FACTORY INSTALLED HYDRAULIC PARKING BRAKES

MODELS: 1991 AND PRIOR TRUCKS WITH HYDRAULIC BRAKES


It has come to our attention that, in certain cases, controls are being added to vehicles in an attempt to use the service brake system for a parking brake. Specifically, valves have been added that provide the ability to hold fluid under pressure in the service brake hydraulic system and cause the service foundation brakes to perform the function of a parking brake.

The entire service brake system used on GMC (division) vehicles meets all applicable Federal requirements and has been designed and tested to assure that all brake components will provide trouble-free operation. Installation of any equipment that results in using what is designed and tested for a service system as a parking brake system (including those that attempt to limit the maximum hydraulic pressure) is not recommended by GMC (division).

Customers contemplating such installations should be advised of this position and should be informed that GMC (division) cannot assume responsibility for any problems that may be traceable to installation of equipment that involved modification of all or part of the service brake system.