GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Accessories 🢒 Power Take-Off 🢒 Cruise Control Schematics
Figure 1:

L18
Object Number: 1815455 Size: FS
Master Electrical Component List
Cruise Control Description and Operation (6.6L and 7.8L)
LG4 and LLY
Ignition Switch - RUN and ACC/RUN Bus Bars and IGN 3 Fuse
AXL/4WD, BRK, HTR/AC, and HYD/AIR BRK Fuses/Circuit Breakers
ENG-1 and ENG-4 Fuses - LG4/LG5
Stop Lamp Switch
Figure 2:

LG4 and LLY
Object Number: 1645694 Size: FS
Master Electrical Component List
Cruise Control Description and Operation (6.6L and 7.8L)
LG5
L18
Ignition Switch - RUN and ACC/RUN Bus Bars and IGN 3 Fuse
ENG-1 and ENG-4 Fuses - LG4/LG5
AXL/4WD, BRK, HTR/AC, and HYD/AIR BRK Fuses/Circuit Breakers
Stop Lamp Switch
Figure 3:

LG5
Object Number: 1816743 Size: FS
Master Electrical Component List
Cruise Control Description and Operation (6.6L and 7.8L)
LG4 and LLY
Ignition Switch - RUN and ACC/RUN Bus Bars and IGN 3 Fuse
AXL/4WD, BRK, HTR/AC, and HYD/AIR BRK Fuses/Circuit Breakers
Power Take-Off - 1 of 2