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Wiring Question GM voltage regulator to alternator

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I'm transplanting a 69 Cadillac engine into a piece of equipment. If anyone is familiar with the wiring between the voltage regulator and the alternator please take a look and see if I've got this right...should have taken better notes when we were pulling the engine, but didn't.

Voltage regulator is a metal box on the firewall which is maybe 3" cubed. On the bottom is a flat connector with four wires. In addition, there is a black ground wire attached to the outside of the box.

The wires on the voltage regulator (looking from the front of the car) are (from left to right) blue then white then red then brown. The blue and white I have positively identified and connected to the plug on the back of the alternator (field wires?). The red is connected to the positive output post on the alternator. The first three I'm pretty confident in. The fourth wire from the voltage regulator is brown and my guess is that it's a negative source and should be connected to the negative post on the alternator. The black ground wire coming off the case of the voltage regulator is also a bit unclear. Does that just go to chassis ground or should it go the battery negative?

If I've got some of this fouled up, please let me know.

Thanks,

Mark

Reply to
Mark Zivley
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I am just wondering why you just don't use an internally regulated alternator. They are more common .

I don't have color codes for your vehicle but here is how a common GM regulator hooks up.

r= relay side of alt (r is stamped on alt) f= field wire from alt (f is stamped on alt) sw= wire from switch L= volt gauge or light. V= to junction box,( regulated voltage fed back to the battery via junction block) If you.have the first 3 right, all that is left is sw and L. But who knows what Cadilac did. You say you are using it in another piece of equipment. I'd ditch the caddy regulator for a generic one say for a 64 implala or any other mid 60's GM that is marked as above.It would make things easier to figure out and I bet they are still under 20 bucks.

Reply to
TOLYN9

mark, i don't have a diagram in front of me, so don't take this as gospel, but I believe that brown wire goes to the charge light on the dash,and then to the key. There has to be a switched wire to the field or regulator or the field will always be energized.

Curly

Reply to
CURLY

Thanks for the help. Brown to switch is now in place and that makes sense.

Mark

Mark Zivley wrote:

Reply to
Mark Zivley

Mark, you do have a light bulb in series with the switch and the regulator, right? The alt and regulator need a resistence on that wire to help 'excite" the alternator. If you don't want to use the light, then a resistor in series will work, if the resistence of the resistor is too high, the alt. wont charge until you snap throttle. Some kind of resistence on that circuit is necessary , or the alt will not work.

Curly

Reply to
CURLY

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