Alternator wiring
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Teching In
Joined: Jun 2017
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Alternator wiring Help have a 1985 Chevy truck stock wiring harness installed a 6.0 ls 2 in it . Alternator has four wires coming out of it . Old one had two wires out of top with a spade what wires do I use now ?
your old 1985 alternator if it was 2 wires and not 3 wires, one wire can go either to the battery output post on the alternator or you run that to the battery, this wire was the voltage reference for the voltage regulator. the other wire goes to the warning light on the dash, or can leave disconnected. but this is assumption without having seen your old alternator.
the alternator that is from your new 6.0L LS2,the LS2 is ~2005 and later, that's all computer orientated and specific to a given vehicle. the voltage regulator within the alternator is a microprocessor, and you'd have to look up the details from a gm service manual if it goes into enough detail to tell you. I can tell you for a 1-wire alternator that's used on 2002 f-body, it's a generator turn on signal and the engine computer puts 5v on it to command the alternator to work, and if the alternator fails the voltage regulator connects that 5v wire from the engine computer to ground and thats how the alternator lets the engine computer know theres a problem. Later years when they started going to 2,3,4 wires off the voltage regulator they do fancy **** with reduced charging and alternator monitoring so it gets really hard to use one when it's not paired with the engine computer is what meant for.
so your options depend on if your using a similar engine computer with the LS2 in your '85 chevy truck, if so then connect it as it had been to the computer. otherwise call some alternator shops and see if they will sell you a 1-wire voltage regulator for the specific alternator you have. Or by a whole new aftermarket alternator made to work with conversions like you are doing.
the alternator that is from your new 6.0L LS2,the LS2 is ~2005 and later, that's all computer orientated and specific to a given vehicle. the voltage regulator within the alternator is a microprocessor, and you'd have to look up the details from a gm service manual if it goes into enough detail to tell you. I can tell you for a 1-wire alternator that's used on 2002 f-body, it's a generator turn on signal and the engine computer puts 5v on it to command the alternator to work, and if the alternator fails the voltage regulator connects that 5v wire from the engine computer to ground and thats how the alternator lets the engine computer know theres a problem. Later years when they started going to 2,3,4 wires off the voltage regulator they do fancy **** with reduced charging and alternator monitoring so it gets really hard to use one when it's not paired with the engine computer is what meant for.
so your options depend on if your using a similar engine computer with the LS2 in your '85 chevy truck, if so then connect it as it had been to the computer. otherwise call some alternator shops and see if they will sell you a 1-wire voltage regulator for the specific alternator you have. Or by a whole new aftermarket alternator made to work with conversions like you are doing.
TECH Regular
Joined: Jun 2013
Posts: 487
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From: Orange, Texas
If you have a DR44 alternator your gonna have to wire it up through the PCM. If you want you can switch to an AD144 alternator and can wire it up directly to a bulb/resistor to your dash. You don't need to wire it up through the PCM with the AD144 .
