How To Diagnose: Inspection

Sight and sound checks
Check relay operation, blower motor rotation, light illumination, etc. Listen for a "click" when some relay covers are pushed down.

Fig 1: Checking Relay Operation
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Simple checks
For example, if a headlight does not come on and a faulty fuse or poor grounding is suspected, replace the fuse with a new one. Or use a jumper wire to ground the light to the body. Determine which part(s) is/are responsible for the problem.

Fig 2: Checking Headlight Faulty Fuse And Poor Grounding
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Checking with instruments
Use an appropriate instrument in an adequate range and read the indication correctly.

Fig 3: Selector Knob And Pointer
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.