Identify the power source and ground
Find the legend or symbol key
Trace the circuit from source to load
Follow wire colors and labels
Check component symbols and connections
Note switches, relays, fuses, and connectors
Read line crossings and junctions correctly
Use reference numbers and page links
Compare schematic to the physical wiring
Verify voltage, continuity, and polarity
Trace one circuit at a time
Start with the load and work backward
Check for normally open and normally closed contacts
Look for splice points and shared grounds
Confirm wire gauge and fuse ratings
Use the diagram revision and date
Cross-check with the service manual
Mark the path as you trace it
Separate control circuits from power circuits
Identify series and parallel paths