Alternator Performance Inspection

Ignition "OFF".
Connect CH A probe to COM signal terminal (Pin No. 1) of Alternator connector and CH B probe to FR signal terminal (Pin No. 3) of Alternator connector.
Warm up the engine to normal operating temperature.
Measure signal waveform of COM and FR wires.
Specification: Refer to Signal Waveform & Data below

Fig 1: Scantool Display - Engine Idle After Warm-Up
Courtesy of KIA MOTORS AMERICA, INC.

COM → Duty (+) Approx. 34%

Duty (-) Approx. 66%

FR → Duty (+) Approx. 58%

Duty (-) Approx. 42%

Fig 2: Scantool Display - Electrical Load (Engine Idle After Warm-Up)
Courtesy of KIA MOTORS AMERICA, INC.

COM → Duty (+) Approx. 34%

Duty (-) Approx. 66%

FR → Duty (+) Approx. 96%

Duty (-) Approx. 4%

Duty (+) from FR terminal increases if electrical loads are ON (head lamp and defrost are ON). The PCM controls alternator current duty using the FR terminal when electrical loads are turned ON.