Alternator issues still-

rickeolis · 12-18-2003, 12:21 PM

OK, I just found that my alternator is indeed putting out (unlike some women I know), and so I need to figure out where the problem lies that I get no charging.

My question is: There is a small device that my 3 prong plug goes into just before the voltage relay on my left hand engine bay console. What is that? It's about 1" cubed, and is black, then it has a plug that goes into the regulator. Could that item be bad, and how do I check it? (I have a nice multimeter.)

I am using the same relay that came with the engine and alternator that I bought and installed recently. It had the heavy black 3 wire cable from the alternator, and I did nothing more than plug it into the same relay, and mounted it to my engine bay.

304065 · 12-18-2003, 12:34 PM

Rick,

That is an RF supressor for the Voltage Regulator. You can take it out and plug the black plug directly into the VR.

I am confused by your second paragraph. You bought a 2.7. 2.7's had externall regualted alternators. So you got the voltage regulator that came with the 2.7, and you mounted that.

A couple questions: Does your '69 have a 14-pin connector for the engine wire harness? My recollection from another thread is they didn't, they just had four pins.

At the end of the day here's what you need: There are four wires that have to connect to the alternator. They are: DF (dynamo field) black, this goes to the voltage regulator DF terminal and to the faston connector on the alternator's brush holder; D+/61, this is the "blue wire" that originates at the warning lamp in the oil pressure gauge, goes in and out of the VR and to a lug terminal on the alt; B+, a fat red wire (actually two fat red ones- one to the starter postiive terminal, the other to the electrial console (14 pin or elsewhere for earlier cars); and the B-, a medium size ground wire, that goes to ground on the console.

Lemme know about whether you have a 14-pin plug and we can take it from there.

rickeolis · 02:02 PM

Thanks John, you have offered to help previously and I appreciate it!

What I am trying to say is that I never broke apart the heavy (3 prong end) bundle that goes from the newer alternator to the relay that also came with my newer engine.

This was independent of the 14 prong connector at the time. Most of those went to grounds (brown), oil pressure\temp (black with colored bands), CIS (yellow) sensors, etc.

The 3 prong bundle contains:
The DF (black wire), it does go from the DF of my alt. to the DF of the relay.
Then the B+ is the two heavy red cables. The larger red one goes to the heavy lead on the engine starter, and the smaller red wire goes to the fuse in the engine bay that is hot when the key is in the on position.
The brown goes to the D- on the relay, and also to the ground terminal on the car.
Lastly, the D+\61 is in question, when I get home, I need to check it out... The blue wire from my guage is not hooked up but does light up when I apply voltage, and I now know that it is the one that should go to the D+\61 terminal.

John, thanks again, I'll update this tommorrow when I find these out!

304065 · 12-20-2003, 06:03 AM

Rick,

You are on the right track. The blue wire is absolutely critical: it supplies current to the rotor to generate a magnetic field. The rotor spins, and that magnetic field induces a current in the stator windings, which is rectified (converted to DC) by the diodes and fed back into the rotor. This is the "bootstrap" concept- it creates its own current, which is why alternators can be so efficient. But you have to have that "pre-excitation" current (Warren's term!) present first-- some alternators have permanent magnets in the rotor but not ours!

Anyway, probably more than you wanted to know, but here's how to check it. Pull out the oil pressure gauge and verify that you have a red wire with black stripe (switched +12v from the ignition) going to one terminal of the bulb holder, and the blue wire coming off the other terminal. Then make sure you have continuity in the blue wire, all the way back to where it connects to the alternator. The best way to check that is to put the ignition ON and ground the blue wire terminal to the engine case. If the light comes on, you're there. If it doesnt, you have to find the fault in that circuit before the alternator will work properly.

Please be careful pulling the gauge out of the dash, and try not to disturb any wires more than you have to. I once started a small FIRE behind my dash. . . which was the impetus for me to learn how this stuff worked, and taught me how to fabricate original-looking wire harnesses!

rickeolis · 12-22-2003, 09:43 AM

John,
I bypassed the RF suppressor, and it works fine now!

I was glad to get into another project on the car though. That is one of the reasons I bought it, I enjoy working on it. While I had the alternator out, I filed the terminals, painted parts, cleaned everything, and even checked the brushes, which look OK.

I was glad to find that my original wiring was not the issue; everything else I converted was good, now I just need to find a newer tachometer.

Thanks for the help, TTYL-