Help with electrical/alternator issue, I'm lost

[ApexRK]

The car is a 97 Kouki with zenki S14 SR, we bought the car with the swap already done so all of the wiring was already done.

Its hard to explain all of this so I'll do the best I can. When we bought the car it was running fine, but it was low on battery power, the alternator had been rebuilt previously so we figured just a battery or something minor. Got the car home, it was hard to start, slow cranking, turns out the alternator was only putting out 10-11.5v. Removed the alt, had it rebuilt, new regulator from what I can see and the alternator guy said it was not charging well when he got it so its clearly a bad alternator. Put it back on the car yesterday, fired it up, but still only 11v or so and within 5mins the car stalled out....not battery left, so I boost it, took the cables off and it dies 2mins later. Then I boost yet again and leave it boosted while running, leave it like that for 5mins then unplug the boost cables and it stalls again. Frustrated I was able to get some help over the phone from a guy we know, former Nissan tech and SR20 guru, he told me to check voltage on the regulator plug wires, 2 wires, one to the dash (dash light) and one that turns on the alternator, I checked it with the car running, yellow wire at 13v, but the white w/red wire had nothing, dash light was not on so I figured it was the wire that turns on the alternator. Called him back and he explained to just find the break in the wire or why its not getting power and then fix it.
So today I check the engine harness that goes to the alternator, starter, fuse box and tranny(reverse light, neutral switch, etc) etc, I find the 2 wires, follow them and they come to a female harness with 8 wires, but its not plugged into anything and there is no male harness to plug into that I can find. The wires on this harness include the regulator wires that I'm looking for as well as the reverse light, neutral switch and vehicle speed sensor wires. (I should note that the previous owner wired the reverse light, neutral switch, speed sensor to some engine compartment harnesses, not sure why, but thats the way it is.) Ok back to the female harness that goes to nothing, I checked continuity from the regulator harness (white wire w/red stripe & yellow wire) to the same color wires at the end of this female harness and they are connected. From what I can see the 2 wires that come out of the regulator harness end up at this female harness, but the harness connects to nothing so to me this tells me the alternator should not know it has to work, but it was like this before and the car ran fine, but at a lower voltage.
Now when i wired up 12v to this white/red wire going to the regulator with the engine runing and BAM! it works, alternator seems to kick in and I'm getting 14-15v off the alternator, no more boosting it either. Shut the car off, and hour later I get back to it and do this again, but nothing, alternator is only giving off 11.5V, but it seems to run fine, no stalling out. So now I give power to both the regulator wires, still nothing, it should be working, but its not, car is barely giving off 11v now.

I'm at a total loss right now. I know when the car was running I did unplug the regulator harness, don't think that did anything, but just thought I would mention it, also when I did this the alternator still gave off the same voltage and this is a freshly rebuilt alternator.

I hope this all makes sense to someone.

Please help me out here, my first taste of SR20 world has been sour and I need to change that.

Thanks in advance.

[ixfxi]

i just skimmed your message, dont expect many people to be able to provide advice on this since most 240 owners are tools who pay shops to do their conversions. there's only a handfull of people (ie: russ, estevan, and maybe me if i wasnt such an idiot) who know the ins and outs of the wiring by heart.

that lower harness is the one that should handle the reverse lamp switch, speed sensor and other stuff on the transmission. those wires eventually end up inside the cabin of the car. the alternator warning lamp may also go through that harness.

anyway, there's really only a few things that you'll need to focus on.

1) make sure your battery ground strap is bolted on well to the car, and that the cable is good. check your grounds, they are equally as important as your posative leads.

2) the alternator basically has 2 wires. the main power lead which charges the batter. the second important wire is the alternator sensing wire, which senses battery voltage. the alternator creates power based on the reading it gets from the battery voltage.

the red/white wire is simply an alternator failure lead. i believe it grounds out when the alternator begins to fail. the ground signal will cause the indicator to illuminate on your dash. this is not needed and the alt will operate without that wire, its only for your convenience.

mike

[ApexRK]

I realize this is a tricky problem so I didn't really expect much, but i figured it was better than not posting.

I know the grounds are good, the battery is in the trunk with thick 4 guage wire and the ground is solid. The alternator sensing wire is the wire that I hardwired to a 12v source, it worked the first time, then it stopped working the 2nd time around, thats whats got me stumped.

The other thing is the harness that goes to the tranny to hook up the reverse light, neutral and speed sensor, does everyone have that wired up through the factory harness or do they have that wired up separately. Since I never installed the modified harness I don't know what is right and what has been "ghetto" installed.

[drftwerks]

actuall alot of the time, the light is part of the sensing circuit, hook it bakc up to that

[projectRDM]

First things first, make absolute certain the alternator is indeed charging.

Remove the large 6gauge charging lead from the rear stud and start the car (insulate the wire end of course). Now take a quality voltmeter and test the output voltage directly on the charging stud. If it's above 13V when running, the alternator is fine. If not, check the belt tension, then remove it and have it rebuilt again.
If it is above 13V, put the charging lead back on and check the yellow wire (5A fuse in the fusebox) for 12V. Also check the ground on the alternator case, the chassis to battery, and the engine grounds and look for any abnormal resistance. In other words, the ground path on the car can fluctuate a little but if there's a significant change between points you need to reground or add a larger ground cable.
From there, check the other side of the charging lead in the fusebox to make sure it's tightened down properly and that the 75A fusible link is tightly seated in the fusebox. Check both battery terminals for corrosion and wear. The only thing I see that stands out is the battery lead to the trunk is a little small. 4gauge wire can handle the current but I always like to make certain there's amperage to spare and use at a minimum 2gauge.

[ApexRK]

R240NA, I checked the alt charging lead and there is nothing, no output voltage whatsoever. So first thing in the morning I'm taking the alternator back to the rebuild shop and having them check it out, more fu*kin money to spend, oh how I love cars.

Could there be anything I have done to damage it? could runing the engine with the regulator plug unplugged cause any damage to it? This alternator has already been rebuilt twice.

[ApexRK]

I figured it out. I took the alternator to the rebuilder today and he insisted on showing he how it works, turns out that with the alt sensing wire not hooked up the alternator will over charge and kill itself which is what it did. The guy who did the wiring on this car when the engine was swapped didn't seem to think the regulator plug needed to he hooked up so as a result this alternator will be rebuilt for the 3rd time, muthafucka! Now I just have to hardwire the regulator sensing wire to 12v source and be done with this madness.

[ixfxi]

I figured it out. I took the alternator to the rebuilder today and he insisted on showing he how it works, turns out that with the alt sensing wire not hooked up the alternator will over charge and kill itself which is what it did. The guy who did the wiring on this car when the engine was swapped didn't seem to think the regulator plug needed to he hooked up so as a result this alternator will be rebuilt for the 3rd time, muthafucka! Now I just have to hardwire the regulator sensing wire to 12v source and be done with this madness.

Remember, the sensing wire should go to the battery - not to just ANY 12v source.

I re-wired my entire car from scratch with custom fuse/relay box, main breaker, the works. One mistake I made.. not a huge one, but still a mistake.. was to connect the sensing wire directly to the alternator. I really didnt understand how that wire worked, I just knew it was touching 12v. The problem I ran into, which wasnt really severe or anything.. is that the car would not emit a good charge until I rev'ed the motor a tiny bit. Once I would rev, the alternator would kick on and everything was good for that drive.

Anyway, wire it up direct to the battery so that the alternator can compensate as needed for the voltage drop between IT and the battery. I would also do what Russ said, increase the gauge of wiring for your battery and alternator main charging wire. Make sure your battery to chassis ground is thick, and it wouldnt hurt to run an extra heavy gauge ground wire to your engine block.

Seriously, people just dont understand how important it is to have your wiring setup properly and in good condition. Ground spots especially, are always over-looked. If you dont have a quality ground, your circuits will not operate properly!!!

Mike / ClearCorners.Com

[drftwerks]

sense wire senses low v in the system and boost the power output of the alt, you need it.

check the wiring dia for the car, and you should find that the light is needed to complete the circuit

[ApexRK]

Thanks for the help. I'm trying to find where that 8 wires harness is suppose to go to so hopefully I can make the wiring look clean rather than having to splice it and solder it at the battery connection.

I'm also going to increase the battery cable size to 2 gauge at least and route the cable properly, its routed all over the place.

[bigOdom1]

remember to put a fuse on the power wire to the front of the car near the battery so as not to have any other problems with current traveling that far'/heat.

[projectRDM]

remember to put a fuse on the power wire to the front of the car near the battery so as not to have any other problems with current traveling that far'/heat.

You mean the rear. The battery lead is already fused through a 100A link in the main fusebox.

[ApexRK]

Well I finally got it all worked out, Yury at Wiring Specialties explained to me a couple things over the phone so I got it working now, connected the regulator wires to the harness yury told me it has to go to and bam it works. Bolted on the a KA alternator i had lying around and its making a nice 14.49v, and both wires off the regulator harness are showing the same, what a nice feeling to finally get something working right, just got to clean up with wiring.

As for rewiring the battery I will definetly be doing that sometime soon, I checked voltage at the battery and got 14.1v compared to 14.49v at the alternator....and yes a fuse will be going in right near the battery.

[drftwerks]

do you know what wires and connectors work

[ApexRK]

do you know what wires and connectors work


not sure what you mean?

[drftwerks]

lol yea sorry i was in a hurry,

i ment to say

what wires fixed your problem???

what were they too?

[ApexRK]

Well the alt regulator wires (sensing and gauge cluster wires) were not wired up to anything, so I wired them up to the proper wires that are part of the main engine compartment harness, this is the same harness that connects to the speed sensor, it comes out the bottom of the fuse box.. The other wires that were also not connected were the neutral switch so those were connected to the 3rd plug down on the side of the fuse box, pins 3&8, since the car was an auto before that plug is different from the manual i believe. The other wires in that 8 wire plug (reverse light & speed sensor) were wired up separately, but I going to clean it up and wire them directly off the lower engine harness that comes from the tranny.

The lesson to be learned here is not to pay some guy you know from a local forums to do the wiring even if he has done it before, pay the pros like Wiring Specialties to get the job done right. So here is what I figure is the cost of unnessecary damage caused by this wiring messup.
Previous owner:
bought new dry cell battery - $150can thinking the battery was dead
rebuilt alternator - $180can
shop time trying to diagnose it, no idea

Me:
rebuilt alternator 1st time - $180can
rebuilt alternator 2nd time - $80can - only regulator this time
various wiring items including soldering iron - $40can
being stressed out to the max and having to spend hours in a freezing cold garage when I would much rather spend it with my fiancee- $1,000,000!!hehe

Total cost which could have been totally avoided - $630can or $535US and thats not even including the tax

[drftwerks]

ahh was sensing wire, haha, awesome