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· Super Nazi Mod
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Discussion Starter · #1 ·
Alright all you little cunt suckers out there, this is one of the very few times that you will see me ask a question. one obd2 alternators there is a battery wire and a 4 wire plug. the white/red and white green goes to the ecu. the black/yellow goes to the ignition hot in on/start. the white/blue goes to the underdash fuse relay box which then goes into the integrated control unit then to the instrument cluster

so what exactly is the purpose for the wires? what is each one for exactly? why does the black/yellow goto the ignition? what about the wires for the ecu? I thought this alt had an internal regulator? does the ecu control it?


I know it may sound a little stupid. but I'm thinking about something crazy :)
 

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i was told they had internal regulators too, i know this dosent answer your question but id like to hear the answer too, only thing i can think of is wires to the ecu tell of low battery, or maybe they are used to over ride the internal regulator at times. hell i dont know
 

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i would say that the wht/red that goes to the ECU is a signal wire, i have a premier Deck that can display battery/ALT voltage, so id say that YES the ecu gets this info, the black/ yellow well yeah you cant leave the circuit open when the car is not running or it will drain the battery, that woujld be the equivelant of having a battery powered light switch, if you take the key out, and its still on, it still drains..remember the alternator is DIRECTLY connected to the battery, so yes if the alternator has a closed circuit, so does the battery, the white/blue i do not remember
 

· Super Nazi Mod
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Discussion Starter · #5 ·
i would say that the white/red that goes to the ECU is a signal wire, i have a premier Deck that can display battery/ALT voltage, so id say that YES the ecu gets this info, the black/ yellow well yeah you cant leave the circuit open when the car is not running or it will drain the battery, that would be the equivalent of having a battery powered light switch, if you take the key out, and its still on, it still drains..remember the alternator is DIRECTLY connected to the battery, so yes if the alternator has a closed circuit, so does the battery, the white/blue i do not remember
thats what I figured its just the ecu wires confusing me
 

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I'm trying to figure this out too, I know the white/blue is the wire that tells the alternator light to come on, it also goes to the multifunction box to tell it that the engine is running, one side of the alternator light is always hot with the key on, the other side goes to the blue/white wire, the blue/white wire changes state depending on if the alternator is charging, if it's charging, the wires state is 12 volts positive, this puts positive voltage on both sides of the alternator lamp, and it doesn't come on, if it stops charging, this status changes to ground, and current flows, causing the lamp to light, as far as the multifunction box, it sees the positive voltage, this causes items such as the oil pressure lamp flasher circuit to work only when the engine is running. this design goes back to even the earliest Honda's, other then the multifunction box, the yellow/black wire is probably field current, this is switched with the key, I also need to understand the functions of the other two wires, as i'm transplanting one of these alternators into a different car. :)
 

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ok i've been going through old honda diagrams, in every single FI honda, the red/white is always going to the ECU, and the green/white is always hot, could the computer be switching this constant hot to turn the alternator on and off? I would assume red/white could be taped off, the blue/white wire is always for the dash indicator lamp, and yellow/black is ignition switched hot, those color codes stay constant in OBD 0, OBD 1, and OBD 2 , I need to verify the constant hot on the green/white wire
 

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ok it looks like on the green/white wire the ecu can switch it between positive and ground, on non OBD honda's and OBD before 1, it's always hot, the testing procedure says to run the car with the headlights on and test between the green/white and battery positive, and it should be one volt or less, this means both sides of the probes are at a 12 volt positive state, so the computer is calling for charge under load, in a non computer car, the green/white could be simply switched on with a relay with ignition and to ground with ignition off and the red/white wire could be taped off
 
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