Advanced Diagnostics

DTC P1549: Charging System High Voltage




General Description
The alternator is driven by the engine generates electricity to supply the necessary power to the electrical system and to charge the battery. The alternator voltage target values of 14.5 V and 12.5 V are achieved by switching the alternator control mode (controlled by the engine control module (ECM)/powertrain control module (PCM)). The alternator output signal is sent to the ECM/PCM, and it varies according to the battery's state of charge, the electrical load, and the engine rpm.

When the IGP terminal voltage of the ECM/PCM is a set value or more and this condition continues for a set time, a malfunction is detected and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The IGP terminal voltage is 16.0 V or more for at least 60 seconds.

Diagnosis Details

Conditions for illuminating the indicator
When a malfunction is detected, the DTC and the freeze frame data are stored in the ECM/PCM memory. The MIL does not come on.

Conditions for clearing the DTC
The DTC and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.