Component Location
General Description
The alternator management system controls the charging voltage output to improve fuel economy, manage alternator load under various operating conditions, keep the battery charged, and protect the battery from over-charging. The ECM controls the output voltage by using a duty cycle (charging control, discharging control, normal control) based on the battery conditions and vehicle operating conditions. It is important to have a stable power supply, so a battery sensor is part of the charging system. The Battery sensor is mounted on battery (-) terminal. It transmits battery voltage, current and temperature information to the ECM. The ECM controls output voltage by increasing or decreasing the duty cycle on the COM circuit to the alternator based on these signals.
DTC Description
If the COM circuit from the alternator to the ECM is open or shorted, the ECM sets a P0620 DTC.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
DTC Strategy | Voltage monitoring
| Poor connection Open or short in circuit Faulty ECM |
Enable Conditions | Case1 | Engine running
|
Case2 | Ignition ON
|
Threshold value | Case1 | Alternator COM line shorted ground or power
|
Case2 | Alternator COM line open
|
Diagnosis Time | 5 sec
|
MIL On Condition | DTC only (NO MIL ON)
|
Diagnostic Circuit Diagram
Signal Waveform & Data
Fig.1) Normal waveforms of COM, FR terminal of alternator at idle.
Fig.2)Normal waveforms of COM, FR terminal of alternator under high electronic load condition
- When the eletronic load (head lamp, room lmap … ) is applied, the duty(+) value of the FR line is increased.