Printed-Heater Lines Check

Run the engine at 2,000 r/min. Check the heater element with the battery at full.
Turn "ON" the rear window defogger switch. Measure the heater element voltage with an ohmmeter at the rear window glass center A. Condition is good if it indicates about 6 V.

Fig 1: Measuring Heater Element Voltage At Rear Window Glass Center A
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
If 12 V is indicated at A, there is a break in the negative terminals from A. Move the test probe slowly to the negative terminal to detect where voltage changes suddenly (0V).
If 0 V is indicated at A, there is a break in the positive terminals from A. Defect where the voltage changes suddenly (12 V) in the same method described above.

Fig 2: Voltage Graph
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.