Mark71

I have a 71 350 Cutlass Supreme Convertible. I also have an ammeter that was installed by the previous owner. The ammeter has never worked and I never much cared.

In the process of figuring out some other wiring issues I learned that I have a 3-wire Delco 10si (I think) alternator. I also discovered why the ammeter doesn't show anything. The connection from the "F" terminal is wired in series to the ammeter, but it gets broken after that. It was wrapped in electrical tape so I couldn't see that it was disconnected. I have no idea where it goes from the break...

The "R" connection is hooked up to the BAT light which works as it should.

So here are the questions:

• It appears the "F" (field sense) wire is not hooked up. How is the alternator working? What is it sensing?

• Why would anyone wire the ammeter in series with the "F" terminal? Would it ever show anything?

• I'd like to take the ammeter out and replace it with a voltmeter. Is there any reason I should reconnect it the way it was "intended" by the PO?

Please have a look at my excellent drawing (its horrible), but you should get the idea of what I am seeing...

Thanks!

Nufo

check this link out and see if it helps ....



http://www.madelectrical.com/electri...reewire3.shtml

BILL DEMMER

you have a 10dn(externally regulated alternator). the F terminal is the field power for the rotor, it should route back to the regulator on the firewall. the R terminal also should route back to the regulator. somebody that shouldn't have touched an electrical system has been busy under your hood. the 2 blue wire ends should be spliced together(currently, there is a green spliced to that blue). if memory serves me, that is the oil pressure idiot light circuit wire(green wire). i would highly recommend you find a wiring diagram for your vehicle and check everything over thoroughly.
that red 10 gauge for the output wire will be fine, 10dn alternators weren't exactly "powerhouses". that connection to the horn relay is actually the main power distribution stud and is exactly where the alternator output terminal should be connected to.

have you measured the charging voltage when the car is running with light electrical load vs. heavy electrical load? i bet you'll find a problem there.


bill

MDchanic

+1, Bill.

- Eric

Mark71

Hi Bill - Thanks for the info.

The green wire is routed to the the ammeter (and NOT original to the car at all). The other green wire which is disconnected from the splice is coming back from the other side of the ammeter and looks like it was intended to be spliced back into the blue (F) wire.

10dn is the model number - you are correct. So knowing it is externally regulated, where would the regulator normally be mounted? What should I be looking for? Sorry for the dumb questions but I want to follow each of the wires and figure out what's going on.

Thanks again,
Mark

455man

The regulator is a little black box on the firewall passenger side if I remember correctly. I think it has 4 wires coming out of it.

boese1978

Here is a pic of the voltage regulator on the firewall, factory mounting spot (to the right of the coil). I just went through the harness that goes to it. Maybe able to help if you have any questions.

70cutlass831guy

not sure if im doing this right but i have a newb question... what is that battery looking thing attached to the voltage regulator?? i just rewired my cutlass back up and mine doesnt have it.. mines a 70 cutlass S model if it matters.

boese1978

That is a condenser. They keep static and "whine" away from your radio.

70cutlass831guy

ahhhhhhhh thanks for the schooling. i have a lot to learn...

Mark71

Thanks everybody for the info. Now to dig into my wiring harness and figure out what's going on...