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Unread 02-07-2010, 10:32 PM
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Now this is where things get complicated just a bit. The Tacoma alternator plug has three wires (R, Y, W) coming out of it and the Lexus alternator plug has more wires of different diameter.

And also you have to realize that the chassis wiring harness is composed of all the accessories the vehicle might have. In the case of my Tacoma I have a radio in the cab and a couple of lights. No power windows, no power locks or any of that monkey business. Then the LS400 is totally the opposite and it has every accessory under the sun including a power hungry stereo with amps. The two chassis harness require COMPLETELY different amounts of power from the alternator. Thus you can see that the Lexus alternator is looking twice as big as the tiny Tacoma 3RZ unit.

So can you guess how much power is needed from each alternator? You can imagine the difference. Now you have to look at the fuses which tell you how much power is the maximum power needed before the main fuse in the circuit blows. When a fuse blows it means that much more power than usual is being consumed by the circuit. It doesn't mean there is a SHORT in a wire but this just happens to be a common cause of too much power being drained through the fuse to the point at which is will burn out. We just need to realize how much power each system is designed for and this will help you understand how the power flows. If you just look at each fuse and hook them up because they match then it will be wrong because the vehicles power systems aren't the same (which obviously means the fuse denominations will be different even though they do the same job but under different loads).
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