K 1500 Truck 4WD V8-350 5.7L (1986)
Vacuum Brake Booster: All Technical Service Bulletins
Brakes - Hard Brake Pedal Feel
GMC NUMBER:
88-T-121
GROUP:
5 - Brakes
DATE:
June, 1988
CORPORATE
NUMBER:
865005
SUBJECT:
IMPROVED BRAKE PEDAL FEEL
MODELS:
1987 - 1988 R/V-20 WITH 5.7L (L05) OR 7.4L (L19) WITH JB7 BRAKES 1984 - 1986 C/K-20 WITH 5.7L (LT9) OR 7.4L (LE8)
WITH JB7 BRAKES
A condition described as a hard brake pedal feel with a cold engine or upon quick reapply of the brakes may be caused by reduced vacuum at the brake
booster Vehicles with this condition can be improved by installing a high flow vacuum brake kit.
SERVICE PROCEDURE
REMOVAL
1.
Remove battery ground cable.
2.
Remove air cleaner.
3.
Remove existing vacuum check valve and grommet from booster. Disconnect vacuum pipe at TBI adapter and remove pipe and hose assembly
from vehicle.
4.
Remove vacuum pipe fitting from TBI adapter.
5.
Remove vacuum fitting for transmission modulator, heating/ventilating and cruise control from inlet manifold in front of distributor.
