Alternator Problem

[dr1ft3r]

Ok, I'm having alternator issues with my race car. I've exhausted damn near all efforts to get this thing to charge and after a ton of research I came up with the revised setup I have, yet it still will not charge. Pictured is a diagram of how I have it wired, I'm hoping someone more knowledgeable than myself can tell me what might be the issue.



So basically I have my Alt power wire with a 100 amp fuse run to the main distribution block for the chassis. I then ran my 'sense' wire with a 10 amp fuse and 100 ohm 1/8 amp resistor to my main ignition and of course, my Alt ground to the chassis. I also have my voltage gauge wired to the distribution block and grounded remotely.

Also, I had the alternator tested and it came back good. Tested the conductivity of every wire and they all seem to be good. I start the car and the gauge shows just over 12 volts. I put my volt meter on the Alt power wire and it shows the same. I pull the positive battery cable and the car dies. I have a brand new red top Optima battery too btw. I can post a pic of a diagram of how my chassis is wired too if that will provide a better perspective.

I'm completely stumped here. Please help. Thanks for reading.

[racepar1]

I'm confused as to why you would completely re-wire your charging system. In any case, what alternator are you running? What car is it? Your charge wire should go up to the battery, not to the fusebox. I'm also confused about that as well though. It looks like you've got a 100amp in-line fuse on the charge wire, but if you have it wired into the fusebox then I would assume that it is correctly hooked up to the charge fuse. That would make your external fuse redundant and useless. I've looked at the charging circuit wiring diagram for a 1992 240sx and it looks NOTHING like yours.

[dr1ft3r]

I've rewired the entire chassis, it's a track car. No factory wiring. No fuse box. The distrubution block is basically the positive terminal to my battery, everything that requires power branches off of it. Starter, ALT, and relay board controlled by my switch panel.

I have an S15 SR in an S14. So it's an 90 amp S15 alternator.

[racepar1]

Originally Posted by dr1ft3r

I've rewired the entire chassis, it's a track car. No factory wiring. No fuse box. The distrubution block is basically the positive terminal to my battery, everything that requires power branches off of it. Starter, ALT, and relay board controlled by my switch panel.

I have an S15 SR in an S14. So it's an 90 amp S15 alternator.

How many pins on the alternator connector?

[dr1ft3r]

Two. The sense wire and the idiot light wire.

[racepar1]

First off, after looking at the diagram for a 1996 240sx I see no need for any resistor. The sense wire gets 12 volts from the charge wire inside the stock fusebox. Second, I think you may have to connect the idiot light wire to 12 volts to get it to charge at all. That wire is normally powered and you might need that power to get the alternator to charge properly. I'm thinking that your sense wire should be powered constant and the "idiot light" wire should be switched ignition power.

[dr1ft3r]

From what I've read, the sense wire needs to see a load to tell the alternator to charge. Hence me wiring it to the ignition. I don't have the idiot light wired to anything so that's probably my issue. I'll wire it in and see what happens. Results coming soon.

[racepar1]

Originally Posted by dr1ft3r

From what I've read, the sense wire needs to see a load to tell the alternator to charge. Hence me wiring it to the ignition. I don't have the idiot light wired to anything so that's probably my issue. I'll wire it in and see what happens. Results coming soon.

According to the factory s14 wiring diagram the sense wire is teed off of the charge wire inside the fusebox. That t junction feeds a 7.5a fuse for the sense wire in the fusebox. I reccomend that you wire yours the same and remove the resistor. The charge indicator wire is fed off the interior fusebox, which tells me that it's probably switched power. Try jumping the sense wire to the charge wire and patching the other wire to your switched ignition wire with the resistor removed. You can do all this in a temporary manner just to test it out.

[dr1ft3r]

That did it, putting together something more permanent now. Thanks for your help man, glad to finally be finished with this.

[ignited]

racepar1, dude you just helped me fix my alternator issue. thank you! I too had removed all wiring in my s13, put in an ARC8000D, chasebays rb harness, and realized the chasebays harness incorrectly wired the sense and idiot light wires. temporarily ran the sense wire to the battery in the car and it worked perfect. rewired it into the ignition switch. you rock man!