Before starting

The following applies to Honda general internal combustion engine vehicles. Since each naturally aspirated, hybrid and electric vehicle including is different, always refer to your vehicle service manual. It is known that Honda vehicles have been using this dual-mode charging system since the late 1990s. And as of 2021, the Two Wire system charging system is in use.

Vehicle charging system configuration

The vehicle charging system is largely composed of the following. It is the ECM that controls everything, and the actual electricity generation is produced by the alternator. ELD is to measure all the electricity consumption in the vehicle and report it to the ECM. Therefore, there must be no electrical devices that the ELD is not aware of.

1. ECM (Engine control module)
2. alternator
3. battery
4. Electrical load detector (ELD)
5. dashboard instrument panel

The importance of ELD and proper wiring

ECM controls the alternator for electricity production depending upon the electricity demand and consumption reported by the ELD. The dual-mode charging system flexibly adjusts electricity generation based on high and low load conditions required by the vehicle.

Therefore, all electrical and electronic devices additionally installed in the vehicle must be made known to the ELD. In this way, the ELD accurately measures the amount of electricity consumption and reports it to the ECM, so that the ECM can properly generate and manage electricity. The ELD is usually located in the middle of the engine room fuse box.

How to check alternator

After turning on the headlights, heated seats, defrost, and radio, increase the RPM to over 2500 and measure the voltage. In this case, the voltage should be around 14.4VDC. If it is about 12.4VDC in high load situation, it is very likely that your alternator needs further inspection and replacement.