[Diy_efi] Starting and Charging

[Dustin Lof]

yes that wire is the same just connect it to the brown
wire in your factory 86 harness, you can test the
circuit as follows

grab a test light and clip it to batt ground, with the
alternator unplugged probe the brown wire, the light
should light with the ign on.  If it lights jump the
brown wire to ground, the batt. light should come on
if it has one. no fuses should blow.

I had a customers vehicle once a 90s chev truck that
would charge at times then not, when it wasnt the
batt. light was on, so the obvious answer seemed to be
replace the alternator, well the customer had already
done that, and it was done again at our shop before it
reached my bay, so I had a prety good feeling it wasnt
an alternator. I rigged up a little harness that had a
light bulb, an alternator connector and an alligator
clip, next I started the engine unplugged the
alternator plugged in this litle harness and clipped
the alligator clip to batt pos. the charging system
was working great but the batt light was still on then
off and flickering.  a little investigating revealed
the exciter wire rubbing on the cab pinch weld above
the transmission bellhousing. a new splice some shrink
wrap and a zip tie all problems solved.

as for your voltage regulator, once you get everything
hooked up proper, with the engine running use a
digital voltage meter,on a DC 20v scale measure the
voltage a the batterey it should be 14.00 to 14.8
above 15 there is a problem and below 13 a problem.
Now switch your meter to AC millivolt scale, you
should not see any more than 500mv AC (if any one
wants to disagree and say thats too high I might agree
500mv is a guess) If you see AC voltage the diodes in
the alaternator are bad

Next you need to measure the ampreage the batterey is
consuming.  If you dont have an inductive pickup
capable of measuring 120a you need to find one.  It is
very important you check this.  with the batt. fully
charged connect pickup to the positive batt cable at
batt, including every cable and wire, sometimes it is
easier to use the neg. cable just remember to flip the
clamp over, start the engine, let it run you should
see 50+ amps for a minute or so but it should start to
taper back to 10 amps if it stays higher than 15, your
batterey has a cell shorted or some other problem,
rember this test is only valid if you measure at the
battery, if you test at the alternator you will read
what the alternator is producing, with the electrical
loads in the truck this reading will be higher

I have seen many bad battereys ruin good even new
alternators 



--- Clayton Martiniuk <wildwood at aptalaska.net> wrote:

> I am sorry for not explaining my dilemma further. I
> have an 94 chevy 350 that has the 94 harness and
> connectors. It came with an alternator with two
> wires connected to it. One wire goes to pos bat
> terminal from alternator output, and one is an
> exciter( from what my service manual says)going to
> the four pin connector. I have this exciter powered
> with 12v. The thing seemed to work for about a day
> and wont work again. Is the voltage through the
> exciter regulated through a generator light on the
> newer style alternators? Have I fried the voltage
> regulator? 
> 
>                      Thank you very much for all
> your advice,
>                                                    
>                                                    
> Clayton Martiniuk>
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