<grimisme@[EMAIL PROTECTED]
> wrote in message
news:3c38eb52-fd43-4fcb-bdbe-c871eb4e916e@[EMAIL PROTECTED]
> Truck details:
> 86 Dodge Ramcharger SE, 360 4x4, auto, tilt, no A/C.
>
> Problem:
> Charging system failure.
>
> Symptoms:
> Electrical outputs diminished (things light light output, power
> windows and wipers are slow, etc). Increasing load on the system makes
> lights go dim, stereo to shut off, wipers to slow, and so on.
> Increasing engine or idle speed does NOT counter this effect, nor
> cause the system to come back up to full power. Vehicle doesn't start
> without a jump.
Besides the charging system failure, it looks like your battery is also
pretty much used up now as well.
>
> Tests:
> Before it died on me I stopped into a Schucks and had them do their
> electrical test. The result pointed to the alternator as the failure.
> I took the alternator in by itself (the first test was done in the
> vehicle). Two bench tests showed the alternator to be fine.
Sounds like a lack of experience there to me. You have to be careful with
some bench tests as well as depending on the equipment that they use they
don't always show the entire picture.
>
> Next I tested the battery voltage with the truck off. Voltage was just
> a touch under 12v, yet I had to jump it in order to get it running
> again.
Static voltage doesn't always give a clear picture. What was the voltage
when it was cranking or rather, when you turned the key to start. As said
before, it looks like your battery is shot as well.
>
> With the truck running I checked voltage at the battery again and it
> still read 11.4. Revving the engine did not increase voltage.
Which as I assume you know, means no charging.
>
> I then disconnected the voltage regulator and ran a jumper from the
> green wire connection to ground to perform a full field test. With the
> truck running again, I tested voltage at the battery leads and it read
> 13. Again, voltage did not increase or drop with engine speed.
If the voltage jumped up when the regulator was bypassed, then it should
be
obvious what the problem is.
>
> My manual indicated the voltage should jump to between 14 and 16
> volts, and to only run this test long enough to get a reading. After I
> saw the voltage went up 13v but stayed steady, I feel I have ruled out
> the regulator as the problem. This is also still under voltage,
> correct? Normal voltage should be around 14v. Bypassing the regulator
> only bumped it up slightly.
Then you would be wrong. The numbers in the FSM assume that nothing else
is
wrong and that is not the case here. A bad or severely discharged battery
can clamp down the voltage to 13V and it could also be caused by a failed
rectifier in the alternator. You could and probably do have multiple
problems going on here.
>
> Following the test procedure in my manual, I then disconnected the neg
> batt cable and then hooked up a test lamp between the negative cable
> and negative post. The light came on. I disconnected the alternator,
> and the light stayed on. The manual says this means there is a short.
I don't see how that could indicate a short. What it indicates is current
flow which is normal. If you have an under hood light, a door is opened,
a
glove compartment light is stuck on, or just about anything attempting to
draw power from anywhere in the vehicle can possibly light that light.
What
type of test light are you using.
>
> Next, leaving the test lamp in place and the ignition off I started
> pulling fuses to find out what system the short is in. The light goes
> off when I pull the fuse at #7 (HORNS) and #9 (DOME STOP LMP). Is it
> interesting to note that the test light will come back on if I pull
> the headlight switch out?
No it isn't. Any time you activate something that draws power, that light
will light. Now I'm not sure why your horn circuit would be drawing power
unless you have something else connected to it but the dome light circuit
indicates that you have a light on somewhere.
>
> Now we come to the crux. It would seem I have a short in both of those
> circuits. But do I really?
There is a big difference between a load and a short. If it were a short,
then the fuse would blow.
>
> Here's why I ask.
>
> The test lamp is acting in lieu of a direct connection of the cable to
> the post. I would expect that the test lamp would of course come on if
> I pull the headlight switch out because lights work even when the
> ignition is off.
>
> The horn and interior/brake lights are also made to work when the
> ignition is off. BUT, I would expect the test lamp to be OFF unless I
> was doing something to close those circuits like honking the horn or
> actually stepping on the brake or turning on the interior lamps.
And you would be correct which indicates that something on these circuits
is
drawing power and you need to find out what. If it were a true short, the
current draw would blow the fuse. Now you might have a defective switch
somewhere in the lamp circuit keeping a lamp on somewhere that is not
normally seen like the glove compartment or some storage area or did you
just forget about the dome light? As for the horn, did you connect some
aftermarket equipment in the truck and tapped into the horn power for it?
>
> I pulled the leads to the horns, brake light switch and interior
> lights and still read voltage at those fuse slots AND the test lamp is
> on unless I pull those two fuses. I jiggled each of the smaller
> harnesses around hoping to see the test lamp blink off but no dice.
You are looking in the wrong place as neither of these circuits have
anything to do with the charging system. At best, you might find
something
that is killing the battery when the vehicle sits for a long period of
time
but this has nothing to do with the vehicle not charging.
>
> My manual does have the wiring diagram, but only shows the circuit for
> #9. For #7, 8 and 10 it only shows their presence on the fuse block,
> not their wiring.
>
> So what do I do here? Does any of this make sense to anyone? Where
> else should I be looking or what else can I test?
>
> Thanks,
> R(k)
The first thing I would do is charge up that battery and then have it load
tested. If it is 5 or more years old, just replace it. Then I would
check
the connections on that regulator and clean them if they are dirty and if
not, replace the regulator as it is not working. The jump in voltage from
11.4 to 13 is significant and shows that the regulator is not functioning.
If cleaning the connections on the regulator and its connector causes no
change, then replace the regulator. The fact that it didn't go above 13
could be caused by many things such as a bad battery or a defective
alternator as well. I would also check the ground strap between the
engine
and the chassis. After changing the battery and regulator, if the vehicle
is charging but still not getting above 13V, I would have someone that
actually knows what they are doing check that alternator again with the
proper equipment to make sure that it is capable of putting out full power
or you will wind up in the same situation again in a short time.
--
If at first you don't succeed, you're not cut out for skydiving
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