Vehicles fitted with 3.0L engine (L3B generator)

The engine control module (ECM) can switch the voltage regulator between two voltages to optimize the charging of the battery.

The low voltage regulator setting is 13.6 volts and the high voltage regulator setting 15.3 volts, measured with the generator at 25°C (77°F) and charging at a rate of 5 amps. These values decrease with a rise in temperature or current flow.

The ECM determines the output voltage setting of the generator. The high voltage setting is always selected by the ECM once the vehicle has started. The ECM determines the period of time that the high voltage setting is selected for.

There are three different time periods selected by the ECM which is dependent upon the vehicle conditions when the vehicle is started:

• The longest period of time is selected if the ECM determines that the vehicle has been 'soaking' for sufficient time to allow the engine coolant temperature (ECT) and the air intake temperature (IAT) to fall within 6°C (43°F) of each other.
• The intermediate time period is selected when the ECT and the IAT are below 15°C (59°F).
• The shortest time period is the default time and is used to provide a short period of boost charge.

At the end of these time periods the voltage is always set to the low voltage setting to prevent the battery from being over charged.

The time periods are variable depending upon the temperature and battery voltage. The target voltage of the battery varies between 14 volts and 15 volts depending upon the ambient temperature and the vehicle operating conditions. Once this target voltage has been achieved, providing the vehicle has been operating for at least the shortest time period, the ECM will reduce the voltage regulator to the minimum setting of 13.6 volts.