Does the 2005 LR3 have a variable (PWM) alternator or a constant voltage alternator?
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4wd Low
Joined: Sep 2022
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Does the 2005 LR3 have a variable (PWM) alternator or a constant voltage alternator?
Currently trying to assess a secondary power system issue on a 2005 LR3 and can’t find if the stock alternator is a fixed voltage or variable voltage (Pulse Width Modulated or ECU controlled) alternator. I can’t find a solid answer anywhere for this particular year. Any help appreciated.
Recovery Vehicle
Joined: Jul 2013
Posts: 821
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From: Collins, Missouri
The description in the service manual says:
The Generator has a multifunction voltage regulator for use in a 14V charging system with 6÷12 zener diode bridge rectifiers. The ECM monitors the load on the electrical system via PWM signal and adjusts the generator output to match the required load. The ECM also monitors the battery temperature to determine the generator regulator set point.This characteristic is necessary to protect the battery; at low temperatures battery charge acceptance is very poor so the voltage needs to be high to maximise any rechargeability, but at high temperatures the charge voltage must be restricted to prevent excessive gassing of the battery with consequent water loss.
The Generator has a smart charge capability that will reduce the electrical load on the Generator reducing torque requirements, this is implemented to utilise the engine torque for other purposes. This is achieved by monitoring three signals to the ECM: z Generator sense (A sense), measures the battery voltage at the Central Junction Box(CJB). z Generator communication (Alt Com) communicates desired Generator voltage set point from ECM to Generator. z Generator monitor (Alt Mon) communicates the extent of Generator current draw to ECM. This signal also transmits faults to the ECM which will then sends a message to the instrument pack on the CAN bus to illuminate the charge warning lamp. For additional information, refer to Generator (414-02B Generator and Regulator - 4.4L)
Does that help?
Jeff
The Generator has a multifunction voltage regulator for use in a 14V charging system with 6÷12 zener diode bridge rectifiers. The ECM monitors the load on the electrical system via PWM signal and adjusts the generator output to match the required load. The ECM also monitors the battery temperature to determine the generator regulator set point.This characteristic is necessary to protect the battery; at low temperatures battery charge acceptance is very poor so the voltage needs to be high to maximise any rechargeability, but at high temperatures the charge voltage must be restricted to prevent excessive gassing of the battery with consequent water loss.
The Generator has a smart charge capability that will reduce the electrical load on the Generator reducing torque requirements, this is implemented to utilise the engine torque for other purposes. This is achieved by monitoring three signals to the ECM: z Generator sense (A sense), measures the battery voltage at the Central Junction Box(CJB). z Generator communication (Alt Com) communicates desired Generator voltage set point from ECM to Generator. z Generator monitor (Alt Mon) communicates the extent of Generator current draw to ECM. This signal also transmits faults to the ECM which will then sends a message to the instrument pack on the CAN bus to illuminate the charge warning lamp. For additional information, refer to Generator (414-02B Generator and Regulator - 4.4L)
Does that help?
Jeff
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