"Jon G." > wrote in message
nk.net...
>I have a 91 Plymouth Acclaim, and the alternator doesn't charge the
>battery. I took the alternator out and had it tested, and there's nothing
>wrong with it. I put a new battery in it, but it still won't charge. I
>checked the fuseable link from the alternator to the battery, and there is
>continuity. Therefore, it must be the computer.
>
> there are 4 connections on the alternator
>
> L1: direct to battery, positive
> L2: direct to battery, negative
> c1: small wire, logic, to computer, activates diode
> c2: small wire, logic, to computer, also battery ground.
>
> I want to activate the alternator continuously and put on an external
> voltage regulator.
>
> What must the voltage (and current), to the logic inputs c1 & c2 be to do
> so?
>
> I have in mind to run a potentiometer between L1 and c1, and adjust it
> until the alternator kicks on.
>
> The schematic shows that c1 goes to the coil of a transformer in the
> alternator, which then goes to one of the diodes (an SCR?)


I had a problem with one of my cars in the past with the alternator not
charging, what this turned out to be was the ground pin on the regulator was
going via a lamp on the dashboard, thus giveing a slight volt raise on the
ground so you got maybe 13V from the 12V regulator, though it took me a long
time to work out why my battery wouldn't charge, turns out the bulb went on
the dashboard, no ground on the regulator, alternator didn't charge the
battery, thus car wouldn't start.... strange how a small item such as a
dashboard light can stop the car from starting ;-)

Chris