External voltage regulator > Internal voltage reg alterna

[brice]

The original (or old) alternator in my 1974 super beetle (with an external voltage regulator) went bad, and I'm replacing with a new one (which has an internal regulator[I believe].

The old alternator setup is as follows:

A post to the right with a small nut holding on a thicker red wire and a thinner black one. Another post with a 3 prong connector carrying wires which lead to an external voltage regulator located under the driver back seat. From these 3 wires a fourth (blue) attatches at the regulator & connects to my generator warning light on the spedometer.

The new setup is as follows:

New alternator has post with a small nut where I presumably connect the thick red + thin black wires as before. Instead of a three prong connecter, there's a single post labeled D+.

I cut a wire off the 3 prong connector (red) and attatched to D+, then disconnected old voltage regulator & spliced the blue wire (gen. indicator light?) onto the red wire at the voltage regulator.

The new alternator appears to work (getting @ 13.3 volts while reving engine across battery posts), although the gen light is staying on after car is off!?

Is this the proper hookup??

Thanks,

Brice

[george4888]

I have switched from the old alternators to the new internal ones. They usually come with a diagram from Bosch, showing how to do the wiring. Or just follow the Bentley manual wiring for a 75 to 79 Beetle, as they all used the internal regulated alternators. The wiring will apply now to your car. If the alt. light stays on , when the engine is off and the key is off, you have the generator/alternator/changing system red light wired wrong.
It should only come on, with the key in the "on" position, as it gets it power thru the fuse box from the terminal number 15 on the ignition switch. Check you wiring to the light and the speedometer back. also, get the Bentley manual for the wiring for the 75 to 79 to follow the change in the wiring. Under the back seat, you will need to combine the two large red wires that go to the front of the car with the red wire that comes from the alternator. And, you will need to splice the little thin blue wire under the seat to any of the three wires that use to go to the three wire prong on top of the old altenator. Good Luck. The alternator is "powered" up by the 12volts that goes thru the light on the speedometer light. The light acts like a switch and turns off, once the alternator is working. If you only have 13.3, did you buy a new alternator??? Godd changing voltage should be 13.5 to 14.5 volts. Yours is much too low to charge the battery. And that is measured at the battery, as you did. ==George4888

[Glenn]

http://www.glenn-ring.com/temp/AlternatorWiringGuide.pdf
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

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[brice]

The GEN LIGHT is still on! It's on with the car completely off - key out of ignition. I have to turn it off by disconnecting the battery. I've checked wiring & everything looks good.

D+ post on alternator leads to blue wire connecting to gen indicator light.

B+ post leads to wire which splits to battery (+) post and ignition [ leading somwehre behind the fuse box].

Any ideas on what's causing this?

Thanks,

Brice

[brice]

Forgot to mention that my new alternator is a Bosch AL82N

[george4888]

The only way I can think of the red light for the charging system staying on, even if the ignition is off and engine is off, would be for there to be a grounded wire. Somewhere between the dash light and the alternator, you much have pihched the wire, where it goes to ground, or in other works, part of the wire is exposed and touching the metal of the car, somewhere. Then the light might stay on, but wait a second. If you wired the speedometer and the warning lights right, that too, should be impossible, as the only voltage going to the generator light in the speedometer is from the fuse box, and that should work only, read only, when the key is in the on position. You have your wires messed up on the fuse box. They may "look" okay or good, as you stated, but they are not correct. A small black wire feeds voltage to the bottom of the warning light cluster. That wire comes from the fuse box, only when the key is in the on position, or from terminal 15 on the ignition switch. Is your coil also on, all the time. You need to check that also.. and if it is, you have your wires on the wrong fuse. ---george4888

[brice]

[george4888]

Go to Radio Shack or other electrical sales places and buy a cheap test meter, which reads volts,amperes,ohms. Or buy a cheap 12 volt test light.
With either one, you can see by the volts reading on the meter or the light being lit up, on the test light, that the coil is "on". JUst attach the black lead wire on the meter to ground and the red wire on the meter to the positive terminal on the coil, marked on the bosch coil as 15 or the positive symbol of "+". With the ignition key , in the on ( run ) position, you can see on the meter or test light, if the coil is "on" or in other words has 12 volts or less going to it. If you get a reading of anything other than zero on the volt meter or not a unlit light on the test light, then the coil is on all the time, once you reconnect the battery, as you said you had to disconnect it to keep things off. And, that would reflect a problem with the wiring to the fuse box. Wrong wire on the wrong fuse. When did all this happen?? Was it ever working right??? LIke , before the alternator change??---George4888

[brice]

Still having 'electrical issues'. The history is as follows. I bought the car a few days ago.. it wouldn't turn over ( dead battery ), so I did some diagnostics & thought maybe it was the voltage regulater ( 1974 SB had externally regulated alternator ). Replaced the voltage regulator and problems persisted. The wiring / idiot lights behaved correctly at the point. So I stick a bosch AL82N in (with internal voltage regulator) and push start her. The alternator seemed to be charging A LOT better than the old one, and so everything looked good. I disconnected the old voltage regulater and ran a wire from the wire that goes to the idiot light (blue) to the voltage regulator to the D+ post on new regulator.

This is where I noticed my funky behavior.. w/ the generator light staying on even when key is OUT of ignition. There's also @ 12V at alternator B+ post -> ground when key is out AND @ 0.38V at coil. Is this normal ??

[george4888]

You will always read 12Volts on the B+ terminal of the new bosch alternator, as that wire goes directly to the battery, so you get that 12V reading. On the coil, you should have a reading of zero or "O", but some delicate meters will give you some small reading on the volts scale, but I think it would be less than the .38volts you are getting. I know my meter will not zero out, when I have it on, like there is some kind of feedback inside the volt/ohm/amp meter. did you ever check the wiring to your speedometer warning light cluster and to your fuse box???----George4888

[brice]