Frew

Hello all

I searched high and low all over the Internet for the answer to my issue and came up with nothing. I just recently completed the L33/t56 swap on my 96 s14. I have driven it a couple hundred miles and two nights ago threw it on the dyno to dial in some part throttle driving, car performed fine on the dyno and I drove it home that night. The next morning I go to drive the car to work and the battery light and the dash brake light come on, they go off if I go above a 2500 rpm and flicker at 2k rpm. On my drive home from work the lights are still on and as I pull into my plan the car starts idling real low, commanding an 11 afr at idle and the windows will barely go up. Turn the car off and it won't turn back on. I let the car cool down and start checking electrical connections, it seemed the alternator power wire vibrated loose, probably from the dyno pulls, I tighter it back up and I jump the car and head down to advance to have the battery and alternator checked. Battery checks out fine but the alternator is only putting out 12v through the wiring. Start driving the car back home and it starts doing the same thing as before. Anyone have any ideas? It's a brand new ls1 accessory drive. Is it possible that the "exciter" wire is not hooked up in the harness? Wiring specialities has a pdf on their website where you have to take the harness apart and loop a brown wire back into the Pcm connectors. I'm going to check the grounds and all connectors tonight.

jcvett56

If you have the blue/green PCM running the L33 a wire should go from the alternator Pin B on the 4 pin connector to Position 15 on the Green PCM plug. Or you could run a 470 OHM resistor from Pin B to +12V ignition if you don't have the means to get a PCM PIN.
I don't know what harness you are using but you can typically grab the wire from alternator plug Pin B and cut it near the coil plug and use the +12V ignition wire there for easy use.

Frew

Thanks, I'm using a red blue Pcm out of a 2000 5.7 van. The harness is wiring specialities, I emailed them and asked them if they have ever experienced this issue and they told me no, and I don't have to loop that brown wire in the harness.

jcvett56

Well Pin 15 on Red connector is for the L terminal, Pin B and is used for charging. Or you can do the 470 Ohm resistor. Does your alternator have a plug on it with wires or is the wire you are taking to dash?

Frew

I'm sorry, I'm ignorant to these terms. L terminal? Pin b? Sorry, I'm new to the ls world, this is my first swap. Update, I pulled the alternator and had it checked, it passed all the tests, I also went around and checked the harness ground, battery terminals, and starter terminals for loose connections and everything seems tight. The alternator has a plug on it that's pinned with one brown wire. Do you know when and how much voltage the exciter wire sends to the alternator? I want to test it with a voltmeter to make sure the Pcm is signaling the alternator to charge the system. Thanks

jcvett56

Pin B on the 4 pin alternator plug means position B. Every plug has a position to let a person know where to put what wire. Since yours only has one wire Then that's the wire that should go into your harness and into position 15 on Red connector PCM side. Just check for continuity with a volt meter.

Project GatTagO

iTrader: (7)

Read this:

http://www.pirate4x4.com/tech/billav.../Part2/#wiring

Andrew

Frew

I checked the voltage of the exciter wire and it starts off as the same voltage as the battery and alternator (12v), and gradually goes down as the entire electrical system loses power. The exciter wire voltage is too high correct? That's why the alternator is not kicking on, it thinks the car has plenty of voltage?

Project GatTagO

iTrader: (7)

I am assuming that you are referring to the L terminal on the alternator as the "exciter" wire. If so, do you have a 470ohm resister wired into that wire?

Andrew

Frew

I am referring to pin b on this connector, that is what my harness had wired and that is what I wired on the pigtail I got from autozone. I picked up some 470 ohm resistors from RadioShack and added a tap a fuse to a 12v switched source and it didn't drop the voltage at all. I'm going to pick up a light bulb today and try it with that. Does anyone else have any other ideas? I assume the alternator is done at this point but I'm more concerned with getting an 8v signal from somewhere

1981TA

iTrader: (7)

maybe this will help.

Project GatTagO

iTrader: (7)

Pin B is the L terminal. If you look on the alternator the pins are usually labeled. Have the alternator tested at the local parts store before getting a new one.

Andrew

Frew

I had the alternator tested and it passed, but the issue isn't present in the first 15 seconds of the car running, and that test only runs for 10-15 seconds. The wiring harness sending 14v to the alternator
for a couple hundred miles most likely killed the voltage regulator. Wiring specialities is going to send me the pin so I can pin the harness and get the proper 8v from the Pcm so it doesn't kill the next alternator.

Frew

So because I hate finding threads with no solutions. I'm replacing the alternator assuming it's fried, wiring specialities has assumed me as long as the idiot light on the dash is illuminating that the circuit is working correctly. I am also adding a 2 gauge ground for the battery and a 2 gauge ground for the motor, both to the chassis. I will update the thread when I get the new alternator from rock auto. Thanks to everyone that tried to help

Project GatTagO

iTrader: (7)

Keep us updated.

Andrew

Frew

Well I changed the alternator and then the car wouldn't start, then I changed the battery and the car appears to run. Everything appears fine.