SirLapsalot

Yea I've seen that dude post some really helpful links and such recently. Love to see that.

azbanks

Cheaper and smaller. It makes it much easier to use a bigger turbo and MAF kit.

Bri Bro

The extra pin is a sense line. It goes to the battery to measure the voltage directly at the battery + terminal. The alternator output lead will have 30-100 amps of current flowing through it so it causes a voltage drop in the wire. The sense line doesn't pull current so the no voltage is dropped in that wire. The regulator will increase or decrease the voltage output of the alternator to offset the voltage drop in the alternator output lead. What the regulator is trying to do is keep the sense line at a set voltage.

I don't have any high current amps or high current loads in my car. My voltage stays around 13.5-14 volts all the time. If you see changes in the alternator voltage, just run a fused wire (like in the diagram) from the battery to the S lead of the alternator and that should make a nice steady voltage at the battery even with changing loads. Just run a wire taped to the alternator output wire from the alternator up to the battery, it doesn't need to be a large gauge, 16-18 gauge should be fine.

supes6

Yeah, it seems like the rebuild shop is confused on the wiring diagrams for this alternator. Maybe they thought the jumper was connected to the exciter circuit - when it's actually connected to the voltage sensing circuit. This still leaves me with the question of why the voltage regulator died so quickly. I'm wondering if rigging the stock cooling duct so it blows on the back of the alternator would help.

lejams

Has anyone come up with a fix for this? I'm having a very similar problem. Within a few months after installing the Nissan, the regulator failed. Had it replaced and tested at a alternator specialist and still doesn't work after reinstalling. The alt is not being excited. I looped some long wires off the plug where I could disconnect and test if need be with the engine running and not running.

One disparity is that when I unplug the blue wire at the firewall with the car running or the ignition in the run position, the meter reads on the blue wire from the ignition equal voltage to the battery. Plugging the wire back in with the car running, the voltage on the blue wire drops to 3.47 volts. To check if there was a problem with the blue wire running through the harness to the alternator, I bi-passed it by Splicing in at the fire wall and running it directly to the alternator. No change, same results. Any idea what is causing this. I have a Ice Shark battery & lighting kit installed.

Tom M'Guinn

I've had my Nissan style alternator for a few months now and haven't had any issues (knock on wood). Are others with this alternator having problems, or is this maybe something unique to a few cars?

For what it's worth, I don't have a big stereo or other heavy loads...

Dave W.

The Nissan alt on my car has been working perfectly for 1.5 years so far.

lejams

The only additions to my car are the Vitesse kit, (been on there for 12 years), and the IceShark battery & headlight upgrades and it's connected as per the instructions. I am running 100 watt bulbs with the Ice kit in both headlight and driving lights, but this should not be a problem. I ran those for years before installing Ice Sharks kits. Everything else is factory. What would cause the the voltage to be reduced in the sense wiring circuitry like that?

I've removed the alternator and plan on taking it to the alt shop again tomorrow morning to have it thoroughly re-checked. Hopefully he'll be able to add an explanation.

I'm getting more efficient at removing the alt, but growing tired of it. Repetition of this nature starts to get annoying. It's just more fun to drive it...

Mikes3.0cabturbo

Interesting I have the opposite to many too much charging voltage, I have tried the sense wire directly to the battery and via switched positive in the fuse panel, both give me 15.6v.....seems to be working fine but according to my electrician at the maximum voltage for a battery charging circuit. I tried disconnecting the sense wire and no charge at all.

Dave W.

Have you tried running the sensing wire directly to the main terminal on the alt? Usually there's a little voltage drop between the alt and battery, so wiring it up directly should bring volts down a little.

Mikes3.0cabturbo

Yep I did, when I first connected it still around 15.5v, but always on then, I will have a look at a new regulator when I have time as it seems most others dont have this issue. Thanks for the suggestion Dave.

lejams

The alternator shop owner found a broken rotor wire and the regulator was toast again, (probably due to the broken rotor wire). He said these alters are no longer Denso parts but are made in China and the rotor wire that was glued on broke off

He put a Denso rotor back in with a new regulator and I reinstalled. Still issues remain although things have changed some, a bit for the better.

The good is that it charges some, but only a fast idle. If everything is turned off, it takes a minute to bring it up to 13.5 on high idle. Turning on headlights reduces the voltage it can achieve by closer to 13v. Turning on more accessories reduces the voltage it can achieve even more and it takes longer. With all accessories off and normal idle, voltage drops below 12v. Regardless of any voltage, the red battery light and antilock lights remain on.

Re the blue and red wire at the fire wall, (red goes to the starter, and the blue sense wire to the alt), when plugged in and ignition switched on, the blue wire reads 3.6v. Alt shop says it should not do this. When it is unplugged the blue wire from the ignition reads equal to voltage at the battery. I bypassed the harness to the alt by running the blue wire directly from the ignition plug straight to the starter, and it still reads 3.6.

Something is knocking the voltage down. Since the ignition wiring seems to check out okay until it's plugged back into the alternator, seems that it must be an issue with the alt itself? About all that's left is bad diodes, or rectifier. After the rotor and regulator was repaired, it bench tested properly at 14v. Is it possible that a diode or set of diodes has shorted and didn't show up on the bench test?

Can anyone offer any input? Pretty frustrating!

Dave W.

If one or more diodes have gone bad then it would output AC volts. Test it by switching your multimeter to AC Volts and take a reading with the car running. A normal alt will put out less than one volt AC.

lejams

Thanks Dave, I tested it for bad diodes at the battery by setting the meter on AC and came up with 0.11 which is well below a spec. of .5v -1v, so if I'm testing it correctly then the diodes are not the issue.

I also did a voltage drop test on both the positive and negative side. The positive side looks good reading .011, but the negative side shows a problem reading 02.6.

I understand that the specification on the negative side should be no more than .2v which obviously is well exceeded. So then there is a grounding issue at some point of connection and I need to start combing for it. I did the voltage drop test on the negative side by clamping onto the alternator housing, metering in between to the neg of the battery. The alt housing is grounded to the engine so I'll look from there. What do you think?

lejams

I retested the voltage drop on the negative side again. Grounded to the alternator chassis to the neg pole on the battery, the voltage drop fluctuates from 0 to 02.5 with the engine running. With the engine and key off, it reads 0. The tests are performed without the red jumper wire from the alt out put to the plug.

One other factor in question is the diode on the cluster. Can the diode be damaged and the light stay on?