Battery Charge Logic
The 5.2.1 ECM (ECM 1 on the M73) monitors the "system voltage" from voltage supply inputs.
The following situations will occur upon engine start up:
- If the charging system output is sufficient, the engine RPM will be normal.
- If the charging system output is lower than normal, the engine idle will increase to provide a higher charge capability of the alternator.
M62: The ECM opens the idle control valve slightly.
M73: ECM I will request via "CAN bus" that the EML control module increase the engine RPM.
Engine idle speed will be raised to 900 RPM until the generator output is sufficient.