Let's start with the warning light. This powered from the ignition (white)
and alt (brown/yellow). With the ignition on and the alt plug removed,
grounding the brown/yellow in the alt plug should light the warning light.
If it doesn't then check the bulb and wiring. If it does, but still does
not light when plugged into the alt, either the alt you have has different
connections to your plug or the alt is bad.
Second, when suspecting or replacing an alt *always* check the voltage on a
brown wire e.g. at the fuse block with the engine running at a fast idle.
You should see approx 14v. If you only see 12v then the alt is not
charging, either due to a break in the thick brown between alt and heavy
current cable, or again incorrect connector or bad alt. Switch on as many
factory loads (i.e. excluding multi-kilowatt sound systems) as you can and
you should still see in excess of 13v.
You can check the thick brown at the alt plug by looking for 12v. Bad
connections can still limit the charging current, which is why the voltage
and load checks above are required.
Without a working meter, or at a pinch a test-lamp, your options for
diagnosis are pretty limited. And 'poke and hope' is not a worthwhile
substitute IME.
PaulH.
----- Original Message -----
From: Scott Allen <scottinarl@hotmail.com>
To: <mgs@autox.team.net>
Sent: Sunday, October 07, 2001 1:28 AM
Subject: Charging System Woes
> Hi,
>
> So the battery on my 74 1/2 BGT dies, (as in lights go out, car dies and
car
> coasts to a halt). Since the alternator light was flickering a bit, I
> figure that there was a problem with the alternator/voltage regulator. I
> get a new alternator, and the battery/car dies again, but this time the
> warning lamp doesn't flicker. I take the alternator back for replacement,
> and the battery/car dies again.
>
> Obviously I'm missing something here. In my other high maintenance
vehicles
> you've got the battery, the voltage regulator and the alternator. Is
there
> anything else on the charging circuit of a B that can go bad and cause
this?
>
> -I checked the connection(s) on the battery and on the alternator and
> they're all good.
>
> -I checked the battery and it's not cracked or grounding out in it's box.
>
> -All fuses are intact.
>
> -Alternator warning lamp does not come on.
>
> -All electricals work o.k., but after the battery/car dies there's not
> enough juice to kick over the starter or keep the car running.
>
> -My circuit tester is dead too, so I can't tell anyone how many amps or
> volts it's pushing through the system.
>
> -Carrying around a spare battery is not an option.
>
> Any help appreciated.
>
> Scott Allen
>
> Dead 74 1/2 BGT
> 52 TD
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