A computer-controlled charging system is undercharging. A lab scope connected to the ground side of the alternator field indicates a 90 percent duty-cycle. Technician A says the alternator may need to be replaced. Technician B says the on-board computer may need to be replaced. Who is correct?
A) Technician A only
B) Technician B only
C) Both Technician A and B
D) Neither Technician A nor B

Question

Quizplus · Accepted Answer

A 90% duty cycle on the alternator field indicates that the alternator is receiving a constant high signal from the computer, which causes it to undercharge. This suggests a problem with the alternator itself rather than the computer. Therefore, Technician A is correct in suggesting that the alternator may need to be replaced, while Technician B's suggestion that the on-board computer may need to be replaced is not supported by the evidence provided.

A Computer-Controlled Charging System Is Undercharging