Power Master brakes - Hard Pedal/Brake Light ON: Overview
Bulletin: 87-5-13BDate: Feb. '93
Ref.No.: 87-240-5
Corp.Ref.No.: 035002R
SUBJECT:
POWERMASTER BRAKES
(DIAGNOSTIC INFORMATION/INSTALL NEW KIT)
MODELS AFFECTED:
1986 LESABRE/ELECTRA ESTATE WAGON
1985-87 REGAL WITH 3.8 S.F.I. TURBO
This bulletin has been revised to include more diagnostics and introduces new repair kits for rebuilding the Powermaster unit. Please discard Bulletin 87-5-13A and replace it with this bulletin.
This bulletin provides brake diagnostic information that will help to correctly diagnose and resolve concerns with the Powermaster Brake System.
If, after following this procedure a technician still has a question, Delco Chassis Division has set up an 800 number for additional assistance.
Call: 1-800-523-0203
CONDITION:
Some owners of 1986 LeSabre/Electra Estate wagons or 1985-87 Buick Regal Turbo vehicles equipped with the Powermaster Brake System may experience either "harder pedal feel" or "increased pedal travel". The red brake warning light may also be illuminated. This should normally coincide with the hard pedal feel or warn of impending hard pedal if a concern is not resolved. It may also momentarily or continuously illuminate in conjunction with the increase pedal travel problem.
CAUSE:
A. "Harder Pedal Feel" symptoms can be diagnosed from this bulletin. There are four likely causes to be aware of:
1. ACCUMULATOR WITH LOW GAS CHARGE: Symptoms - Pedal is momentarily hard and/or brake warning light flickers on normal to fast brake applies.
2. PRESSURE SWITCH FAILURE: Symptoms - Pedal remains hard on all applies and pump fails to run.
3. PUMP FAILURE: Symptoms - Pedal remains hard on all applies and pump fails to run or may run continuously (with or without brake application).
4. INTERNAL OR EXTERNAL LEAKAGE: Symptoms - Pedal remains hard on most or all applies. Brake fluid may be present on outside or rear of unit. Pump runs continuously or cycles frequently (with or without brake application).
B. "INCREASED PEDAL TRAVEL" symptoms can be diagnosed from this bulletin. If this symptom is recognized in conjunction with "HARDER PEDAL FEEL", follow the diagnostic procedures for "harder pedal feel".
NOTE:
Replacement of the complete Powermaster assembly is not required to correct most customer concerns. Part kits are available that will resolve most concerns with this system, and eliminate unnecessary replacement of the complete Powermaster assembly.
See Figures 1 and 2 for component identification.