POWER BRAKE ASSIST

Service Brakes, Hydraulic

Summary

Summary of information from manufacturer: In analyzing this matter gmidentified three primary sources for the complaints.the first involvesa gradual deterioration in performance of belt driven vacuum pumps.ac-cording to GM, vehicles equipped with vacuum pumps are also equipped witha low vacuum warning light, which is illuminated when booster vacuumfalls below 10 in. Hg.this signals the driver that maintenance is need-ed.the second source of complaints was traced to a quality control prob-lem associated with one of the brake booster diaphragm suppliers. Use ofparts from this supplier was discontinued in September 1984.the thirdcomplaint source identified by GM is the low vacuum warning light in 1982models. According to GM, the light indicated low vacuum when there was noproblem or a leak in the switch resulted in reduced vacuum and illumina-tion of the light.this was also traced to a GM supplier that was dis-continued in 1982.GM issued field service information covering switchreplacement in late 1982.analysis: GM has identified specific vehicle components responsible forreduced power brake vacuum assist among the subject vehicles.the numberand nature of the ODI and GM complaints received along with the allegedaccidents reported indicate a potential vehicle safety problem.status:the final report concerning the owner survey from theautomobile club of southern California was received on 6/10/87.===

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