GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2008 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Power and Signal Distribution 🢒 Wiring Systems and Power Management 🢒 Upfitter Provision Schematics
Figure 1:

X103 - Upfitter Auxiliary Wiring Connector
Object Number: 1909614 Size: FS
Master Electrical Component List
Control Module References
PTO Connectors
C102 - Upfitter TRANS OPT Connector and Internal Mode Switch
Serial Data, Speed Sensor
C305 (Upfitter Lighting Connector)
Figure 2:

PTO Connectors
Object Number: 1909616 Size: FS
Master Electrical Component List
Control Module References
X103 - Upfitter Auxiliary Wiring Connector
w/o LF6 2 of 2
LF8/LMM with CTF
w/LF6