Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage..

Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to " Com Circuit Inspection " procedure.

IG "OFF" and connect scantool.

IG "ON" and Measure signal waveform at Com terminal of alternator.

Measure the voltage between power supply terminals of main relay harness connector and chassis ground.

Is the measured waveform within specification ?

	▶ Go to "Check Open in harness" as follows.
	▶ Go to "Check Short in harness" as follows.

IG "OFF" and disconnect Alternator and PCM connector

Measure resistant between com terminal of alternator and PCM harness connector.

Is the measured resistance within specification ?

	▶ Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure. note There is a memory reset function on scantool that can erase optional parts automaticallydetected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others
	▶ Repair open in harness and go to "Verification of Vehicle Repair" procedure .

IG "OFF" and disconnect Alternator and PCM connector

Measure the resistance between com terminal of the alternator harness connector and chassis ground.

IG "ON" and measure the valtage between com terminal of the alternator harness connector and chassis ground.

Is the measured resistance and voltage within specification ?

	▶ Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure. note There is a memory reset function on scantool that can erase optional parts automaticallydetected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others
	▶ Repair short in harness and go to "Verification of Vehicle Repair" procedure .