Guest mkokimoto Posted March 9, 2004 Share Posted March 9, 2004 I've tried to use the search button and I've also done a search by hand back about 5 or 6 pages. When I got the car, there was actually another internally regulated alternator there, according to bang it was a tested alternator, an LR160 from a maxima or something. It had a pigtail on there, with a thick wire going to the T connector which was joined with the + connector. I took that lead and hooked it to the battery, and hooked the other wire to the ignition on terminal. I figured all would be well since the pigtail came from another car, a maxima. Basically the wiring fried itself, the thin wire burned up and the car was overcharging. So I went to the junkyard and got another alternator. Before installing the new alternator, I rewired my vehicle from scratch, removing the old harness in it's entirety and placed a new internally regulated 280zxt alternator in place. I wired my alternator according to this site: http://www.zcarcreations.com/technical/lr160term.htm Before installing the alternator, I had it tested at autozone and at kragens. It was okay, charge current okay, no excess noises, etc. I grounded the alternator to the body, and also created a brand new T connector. One wire to sense, which is always on the battery, and the other wire to an idiot light, and from the idiot light, it goes to ignition. the sense wire goes directly to the battery positive terminal. I also replaced the amp meter with a voltage gauge from a 280. I used the idiot light in the gauge. When I turn the car to the on position and not start it, the idiot light comes on. When I start the car, the idiot light stays on. when I drive the car, the idiot light gets brighter. The voltage meter reads in the high 15's, my dvm reads at 16 volts. I leave the headlights on when I drive the car to make sure the alternator doesn't overcharge the battery. I have an optical ignition system, so I don't need a diode inline of the ignition/idiot light wire. With the headlights on, it still reads about 16 volts. With the headlights off, it reads 16 volts. the battery is a standard and known good battery. My friend's dad suggested that I use the original alternator and build my own transtorized voltage regulator, using a common transistor with diodes hooked to the middle leg to bring the trip voltage up to about 13 volts, and something weird like that. I'd rather not do that. If it helps any, I have only 5 circuits in the car. Headlights, tailights, running lights/gauges, igniton and turn signals. could the lack of current draw cause the alternator to overcharge? what about the idiot light? Help is appreciated. Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted March 9, 2004 Share Posted March 9, 2004 There is a thread about the same issue, I remember it because someone decided they wanted to try to make fun of the answer I gave. Basically the problem is that there is a circuit that basically "primes" the alternator which is normally referred to as the "exciter wire". If your idiot light is wired wrong, it will connect power to the exciter wire in the ON position rather than just the START position on the ignition switch. It has been a long time since I dealt with this issue so I cannot tell you the specific solution, but let me know if that doesnt help and I will see what I can find. Quote Link to comment Share on other sites More sharing options...
Guest mkokimoto Posted March 9, 2004 Share Posted March 9, 2004 There is a thread about the same issue' date=' I remember it because someone decided they wanted to try to make fun of the answer I gave. Basically the problem is that there is a circuit that basically "primes" the alternator which is normally referred to as the "exciter wire". If your idiot light is wired wrong, it will connect power to the exciter wire in the ON position rather than just the START position on the ignition switch. It has been a long time since I dealt with this issue so I cannot tell you the specific solution, but let me know if that doesnt help and I will see what I can find.[/quote'] If it's wired to the start position, then the idiot light would only turn on for those few seconds it's on the start position. After that, the start circuit will be de-energized and it will be an open circuit. That would cause the idiot light to never turn on when the vehicle is in the on position. There's gotta be another reason i think. Yea, I realize that the idiot light circuit is the exciter wire circuit, and the other wire is the sense wire. I've been told that this circuit only draws current until the alternator can create a field of its own. Maybe there's another way? Or i might be able to pull off the manual charging trick by wiring the sense wire to a switch in the cab... and turning that switch on and off manually... but that kinda sucks, ya know... i have a hard enough time remembering my headlights are on/off. lol. Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted March 9, 2004 Share Posted March 9, 2004 If it's wired to the start position' date=' then the idiot light would only turn on for those few seconds it's on the start position. After that, the start circuit will be de-energized and it will be an open circuit. That would cause the idiot light to never turn on when the vehicle is in the on position.[/quote'] No, that would cause the idiot light to never turn on by that particular circuit when the vehicle is ON. When the idiot light is triggered by a failing alternator, it is a different process which turns on the light. I am pretty certain that this is your problem, I will look for the book with the diagnostics procedure in it so I can provide you with the details. It's a pretty easy fix. I had this exact same problem when I was building the wiring for my old truck from scratch, and fixed it in about 5 minutes after reading the page in the book. Quote Link to comment Share on other sites More sharing options...
Guest smoov280zx Posted March 10, 2004 Share Posted March 10, 2004 This isn't anything helpful, but the same thing happened to me with an OEM type replacement. It just started charging like mad one day, red light on and all. I rode around for a day or two with the lights, radio, radar detector, rear def and vent going all the time just to get it down to about 14 and make the light go out . Its stopped by itself before i could get it checked out. Is this something that happens in z's? Mitch Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 15, 2004 Share Posted March 15, 2004 The alternator will also overcharge if it is not getting a good reading of voltage level back from the battery on the "sense" input of the alternator. I think it is the "S" on the diagrams and maybe even stamped on the alternator. WARNING: IF you are in a 280Z, and you are reading high voltage with the charge light on, check your fusible links...... http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=32315 read my new thread ^ mine was blown and caused exactly that problem. FYI -Mine is a 280ZX alternator with jumpers in place of the mechanical regulator to convert to solid-state regulation. Quote Link to comment Share on other sites More sharing options...
Mudge Posted March 23, 2004 Share Posted March 23, 2004 The alternator will also overcharge if it is not getting a good reading of voltage level back from the battery on the "sense" input of the alternator. If too thin of a gauge wire is used it will kill some of the voltage on the line, making it read less than actual, which could be one cause. Quote Link to comment Share on other sites More sharing options...
Guest mkokimoto Posted April 21, 2004 Share Posted April 21, 2004 The alternator that wouldn't stop charging has finally stopped charging. Solution: change the battery. I thought the old battery was good, but apparently not. I put a battery that I had sitting for a while into the car after checking it with a hydrometer and the car suddenly charges to ~13 Thanks for the help guys. Quote Link to comment Share on other sites More sharing options...
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