Before you search for a diagram, you must identify which ECM your C7 has. Caterpillar used two primary configurations on the C7:
Lift the black plastic cover over the ECM. There is often a sticker inside the cover listing every pin number and its function. If that sticker is gone, you need the printed diagram. Cat C7 Wiring Diagram
Physical copies are often sold as part of a complete service manual set. Before you search for a diagram, you must
: This is the primary interface for engine control. Pin 70 is typically the key switch wire, while pins 52, 53, and 70 often handle power delivery. Before you search for a diagram