GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Antilock Brake System 🢒 Brake Pressure Modulator Valve Hydraulic Flow Chart
Figure 1:

Normal Braking Mode
Object Number: 333254 Size: LF
(1)Master Cylinder Reservoir
(2)Master Cylinder
(3)Combination Valve
(4)Right Front Isolation Valve
(5)Left Rear Isolation Valve
(6)Rear Pump
(7)Right Rear Isolation Valve
(8)Right Rear Dump Valve
(9)Rear Drum Brakes
(10)Rear Accumulator
(11)Left Rear Dump Valve
(12)Right Front Dump Valve
(13)Front Disc Brakes
(14)Front Accumulator
(15)Left Front Dump Valve
(16)Left Front Isolation Valve
(17)Brake Pressure Modulator Valve (BPMV)
(18)Front Pump
Figure 2:

Isolation Mode
Object Number: 184239 Size: LF
(1)Master Cylinder Reservoir
(2)Master Cylinder
(3)Ambient Pressure
(4)Master Cylinder Pressure
(5)Hold Pressure
(6)Accumulator Pressure
(7)Combination Valve
(8)Rear Isolation Valve
(9)Rear Dump Valve
(10)Rear Wheels
(11)Rear Accumulator
(12)Rear Pump
(13)To Front Channels
(14)Brake Pressure Modulator Valve (BPMV)
Figure 3:

Dump Mode
Object Number: 184241 Size: LF
(1)Master Cylinder Reservoir
(2)Master Cylinder
(3)Ambient Pressure
(4)Master Cylinder Pressure
(5)Hold Pressure
(6)Accumulator Pressure
(7)Combination Valve
(8)Rear Isolation Valve
(9)Rear Dump Valve
(10)Rear Wheels
(11)Rear Accumulator
(12)Rear Pump
(13)To Front Channels
(14)Brake Pressure Modulator Valve (BPMV)
Figure 4:

Reapply Mode
Object Number: 184243 Size: LF
(1)Master Cylinder Reservoir
(2)Master Cylinder
(3)Ambient Pressure
(4)Master Cylinder Pressure
(5)Hold Pressure
(6)Accumulator Pressure
(7)Combination Valve
(8)Rear Isolation Valve
(9)Rear Dump Valve
(10)Rear Wheels
(11)Rear Accumulator
(12)Rear Pump
(13)To Front Channels
(14)Brake Pressure Modulator Valve (BPMV)