Electrical Alternator not charging after terminator 2 install.

Sfab79 · Aug 31, 2025

I run a procharger,

Yes Nicky, it seems like it….. I was just talking to a friend of mine earlier which I did his Terminator X swap and we were counting how many I’ve done I think I’m at 11 or 12 of them now, and yes, I guess you could say Murphy’s Law has found me

Sfab79 · Jun 12, 2026

Hey all thanks for all the help, unfortunately up here in Canada don’t get to drive in the winter time, ha ha so I picked up where I’ve left off and does anyone find it strange, I have my test light hooked up to the negative side of the battery And my light on the alternator body and the light lights up, which is quite strange but no wiring shorts or anything car runs, but again only getting 12 V on my terminator 2 tuner and with voltmeter at battery, even with ignition on test, light light is on when touching the alternator battery. Any suggestions?

Noobz347 · Jun 12, 2026

If the diode in the alternator is bad, it can back-feed.

Disconnect you alternator wires one-by-one and repeat your trouble-light test. The feed wire will send juice back through the alt to the chassis if the diode has failed but with the engine running, will charge like normal.

Trouble is: You have a dead battery any time it sits for any length of time.

Sfab79 · Jun 12, 2026

Noobz347 said:
If the diode in the alternator is bad, it can back-feed.

Disconnect you alternator wires one-by-one and repeat your trouble-light test. The feed wire will send juice back through the alt to the chassis if the diode has failed but with the engine running, will charge like normal.

Trouble is: You have a dead battery any time it sits for any length of time.

Thanks very much for the reply! I actually have a brand new battery in it

Sfab79 · Jun 12, 2026

I just pulled my three wire terminal and light is not on

Noobz347 · Jun 12, 2026

Replace or rebuild

Sfab79 · Jun 12, 2026

And also with engine running, it wasn’t charging at all either which I’m finding very quite strange. I’ve also disconnected the two wires that go to the positive post on the alternator black with orange. I did that first off and it still wasn’t charging.

Sfab79 · Jun 12, 2026

Noobz347 said:
Replace or rebuild

If I’m not mistaken, I have the same problem last year when I bought an alternator for a test and it was doing the same thing

Noobz347 · Jun 12, 2026

Sfab79 said:
If I’m not mistaken, I have the same problem last year when I bought an alternator for a test and it was doing the same thing

If that is the case then you may still have a wiring short somewhere in your swap that is eating these alternators.

Sfab79 · Jun 12, 2026

I can’t remember, though if I had the two black wires hooked up to the positive post on the alternator though when I had the new alternator in it, so looks like I’ll be buying another one

AeroCoupe · Jun 13, 2026

So I’m curious. Is this a stock alternator or did you upgrade to a 3G?

Sfab79 · Jun 23, 2026

This is a 3G alternator, and I put a new one in today and instead of my test light being super bright like before, it’s very dim light now, but still running 11.9v, very very strange… question… peeps that are running a holy terminator to set up are you connecting your two black wires with orange tracers to the back of the alternator and to the positive side of the starter solenoid?

AeroCoupe · Jun 24, 2026

I don’t think your ECU makes one difference in how a 3G swap works. I have one on a carb setup and one on a EEC-IV setup and both are wired the same.

The two black wires cannot carry the current that the 3G puts out so you need to run a single 4 ga wire with a 125A fuse from the post on the alternator to the battery side of the original starter solenoid (not the one on the mini starter if you have one installed) or directly to the positive terminal on the battery. The rest of the wiring is pretty straight forward.

Sfab79 · Jun 26, 2026

Excellent! Thank you for the help! Yes, I am not using the black wires with the orange traders. I have them taped up and disconnected. I am running the four gauge wire that is included in the 3G alternator kit from LMR, everything worked OK before I did my terminator to set up and I do have the four gauge wire going to the battery side of the OEM starter solenoid, just wondering if anyone else has the black wires with the orange tracers disconnected or hooked up to the OEM starter solenoid, as it looks like they go into fusible links

AeroCoupe · Jun 26, 2026

They don’t do anything but bring power from the alternator to the starter solenoid. I completely removed the ones out of the harnesses on my cars.

You need to verify the rest of the wiring on the alternator.

Sfab79 · Jun 28, 2026

Right on man thanks for the help, so I did an overlay and got power to the green with the red tracer, now I have 12 V key on engine off at the D plug, but unfortunately still don’t have the battery light illuminating, when Keon engine off and I’ve also swapped lightbulbs and still nothing… is there any tests for the resistor on the cluster? Or any bypass?

AeroCoupe · Jun 28, 2026

My understanding is that the resistor is only there in case the bulb burns out. They are in parallel not series. Bulb has to be an incandescent type and not an LED. If the bulb is good it should energize the field on the alternator and work.

Have you pulled the instrument cluster and checked to see if you have power and ground on the printed circuit where the alt light is installed? Have you checked the bulb base that locks into the cluster to make sure power it getting from the tabs that contact the printed circuit to where the bulb installs?

Sfab79 · Jun 28, 2026

Yes, I have pulled the cluster and have 4.5 ohms across the battery light with the bulb in, I’ve also used the same bulb and socket and swapped between the seatbelt light and the battery light and the seatbelt light works with either socket or bulb, I have also checked the yellow wire at the alternator on the D plug and have 12 V on that also, have also checked the resistor on the cluster and have 4.5 ohms also, this seems to be a real head scratcher, lol

AeroCoupe · Jun 29, 2026

Do you have 12V up to the resistor and bulb on the cluster when you turn the key on?

Electrical Alternator not charging after terminator 2 install.

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