GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Crew) C4/C5 🢒 Brakes 🢒 Air Brakes 🢒 Air Brake System Schematics
Figure 1:

Air Brake Warning
Object Number: 1351385 Size: FS
Master Electrical Component List
Brake Warning System Description and Operation
Air Brake System Schematics
Ignition Switch - OFF/RUN/START, RUN/START and START Bus Bars
GAUGES, L-RR TRUCK, R-RR TRUCK, and SIR Fuses/Circuit Breakers
Power and Indicators
G101 - 1 of 2
Figure 2:

Air Brake Dryer System
Object Number: 832310 Size: FS
Master Electrical Component List
Brake Warning System Description and Operation
Air Brake Warning System Schematics
Ignition Switch - RUN and ACC/RUN Bus Bars
Ignition Switch - OFF/RUN/START, RUN/START and START Bus Bars
AXLE/4WD, BRAKE, CHASSIS, and HTR/AC Fuses/Circuit Breakers
GAUGES, L-RR TRUCK, R-RR TRUCK, and SIR Fuses/Circuit Breakers
G112, G113, G203 - 4 of 4, G204, G205, and G400