Many malfunctions in the electrical system are caused by poor harness(es) 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 "Control Circuit Inspection" procedure.

Ignition Switch "OFF"

Refer to "Shop Manual" and disconnect the alternator connector.

Ignition Switch "ON"

Measure voltage of Pin No. 1(com) of the alternator connector and chassis ground.

Fig.1 ) Measure COM Terminal Pullup.

Fig.2 ) COM Terminal Pullup Duty Waveform. Approx. 33% (-).

Is the measured value within specification?

	▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of vehicle Repair" procedure.
	▶ If no problems were found with the circuits or connectors, Replace the alternator and go to "Verification of Vehicle Repair" procedure.