The Stovebolt Site Forums The Shop Area The Electrical Bay 1-wire to 3-wire alt. conversion

I'm trying to convert from 1-wire to 3-wire, have wired it based on info (it's all consistent (yes, I also used Mad Elecrtical site/info)) I got off the Internet, but the idiot light won't come turn off once engine is turned on. The #1 alt. spade is connected to the light, which is inline with ign. accessory switch. And the #2 alt. spade is connected to battery connection/bolt on back of the alternator.

Basically, the idiot light is on when ignition is switched on, but doesn't go out once the engine is started. I think it's still operating as a 1-wire alternator. I have to rev the engine to excite the alternator. Frustrating.

Any suggestions would be greatly appreciated.

Regards.

Starsfan,

Did you buy a new 3 wire alternator, or did you have a new regulator put in your old single wire unit.

You have it wired properly and your guess about still acting like a single wire sounds accurate.

I won't ask you why you did this change, but I'll bet it's the regulator.

Stuart

Idiot lights will stay on until the alternator is excited. That is why over the road trucks have volt meters these days. A volt meter gives you an indication of what your entire electrical system is doing. You can be charging but if you have too much draw you can actually be discharging the battery.

Starsfan,

A Delco regulator #DA-94SE is a self exciting (1 wire only) regulator. It has two tabs and looks exactly like a Delco D668 which is a 3 wire regulator.

It sure sounds like the DA-94SE isn't supplying ground to your charge light/key wire after the alternator is revved up and charging. Again, my guess is that #1 is a dummy terminal, either that or your wire from key to #1 isn't contiguous.

Stuart

Are you shure the alt. you put on is good? Put a volt meter on & see if it is acualy charging or not.

It is...I've had it a couple of years and it charges the battery fine. I've tested it before (many times in the past) and it's always fine. Thanks.

You indicated that the #2 connector is wired to the battery connector terminal. Try removing that wire and running the wire from the #2 connector to the ignition switch - ign on. It should solve your problem.
Fred

Fred,

Share your secret. How would this work.


Stuart

Greetings,
I just repalced a generator with a 3 wire alternator (7127). I would like to verify the reference to no.1 and no.2 positions and relationship to the "R" and "F" marking on the back of the alternator. I thought I had it set up correctly, but found my battery had drained this morning. Thanks Ralpho.

PS: I will keep reading incase you already covered this topic in other postings. Thanks

Ralpho,

From another Northern Californian, welcome to the Stovebolt. SI alternators were usually marked with 1 and 2, but can be marked with the letters R and F as well.

#1 corresponds to R and #2 corresponds to F. 1 on the alternator is the switched (key) wire that initially excites the alternator and #2 ties into the system wiring to monitor and adjust the internal regulator.

A failed diode inside the alternator will allow the battery to discharge while the rig is parked. It might be worth having a shop test your alternator. Good luck.

Stuart

Stuart,
Thank you for the response. First of all my truck is a 1956 6400 dump. Since the alternator was too expensive to replace I thought I would make the effort and convert to an alternator. I first had the #2 wire connected to the horn relay number #3 tab. That is what I think caused the battery to drain. I then switched the wire to the ballast resister since it should only be hot when the key is in the "on" position. Things seemed to check out ok with that change. For some reason my wires started to fry when I left the key in the "on" position for a long period of time. Thank goodness someone noticed smoke coming from under the hood. Just to be clear can you tell me where I should connect the #1 and #2 wires? Thanks Ralpho

Ralpho,

It's fine to wrap the #2 wire around and connect it to the large BATT terminal on the alternator itself. #1 needs to see a key switched voltage. The coil + is a standard connection point, but sometimes this results in engine run-on after the key is turned off. That #1 wire will actually power the ignition after the alternator starts to charge, hence the inability to shut the engine off.

They make a little pigtail for the DA plug that includes a diode in series with #1 wire to prevent the run-on. I don't know if a '56 had a charge indicator light (GEN light) on the dash or not. If it did, this would have been connected to voltage regulator terminal #4. This would be a place to connect alternator #1.

I might be confusing you...or myself. I have enclosed a link that might show it more clear. Take a look and holler if things still look bleak.

http://www.hotrod.com/techarticles/marlan_davis_technical_advise/photo_22.html

Stuart