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howdy - I have a quirky 1990 F-250.
Bought it back in 2005. Had few if any problems with it - it always
started up and ran fine. Just didn't drive it much.
After 6 months, I forgot to turn off the dome light, and the battery
went dead. Replaced the battery in late 2005, and started it up and ran
it around every couple of weeks.
Started to use the cab for some tool strorage and I guess a box
something eventually fell off a pile of other boxes, and bumped up
against the power lock switch, and I guess that constantt operating of
the power door lock switch killed the second battery. So I clearned out
the cab, got a new battery, and thought my problems were solved. Went
back two weeks later, and the battery is dead again.
Borrowed a battery from a friend of mine. Followed the troubleshooting
directions in both the Haines and Chilton books.
Checked the voltage at the battery - 12.60 volts.
Revved up the throttle to 1500 RPM - went to about 13.50 volts, which
was between the 0.50 and 2.00 volts listed in the manual
Turned on the lights and heater and revved up to 2000 RPM - didn't go
above 0.40 volts - which might suggest that the alternator is not charging.
Then turned off the motor, removed the key from the ignition,
disconnected the negative terminal. Used the multimeter to see if there
was any voltage from the negative post to the clamp - there was.
Directions then said to disconnect the alternator. If there was no
voltage on the meter - the alternator is faulty. I had voltage - so it
directed me to pull each fuse out and see when the voltage wasn't
present. I pulled each fuse and the voltage was still there.
So I still don't know where there is a short that is draining my battery.
Any other ideas?
Oh - what would going to Sears or a car parts place for a charging
system check show me at this point?
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Your voltmeter is going to give a reading at the slightest hint of
continuity... Parasitic draw is considered in amps and it is in amps that it
should be measured (milliAmps, actually).
A small clue.... I have been quite successful in this trade for nearly 40
years.... I am doing this out of the kindness of my heart (such as that may
be).... If you want help - listen... Your method is going to lead you
astray... it is an inappropriate method.... How can I make that point any
Another clue... acceptable parasitic draw is about 50mA (that's 50 milliAmps
or 0.050 Amps). If you are to find what loads are acceptable and what loads
are not, you need to know the current draw of each particular load.....
However, I only fix these things for a living..... and I have offered some
sage advice.... If you plan on fixing this in a timely manner, think
"Kirschoffs Law"... FWIW, this is a very basic electrical principal....
unfortunately, this principal will only tell you that the voltmeter is an
inappropriate tool for your test purposes....
This thread is going to be fun to watch....
I don't know if this applies to the F-250 or F-350 series trucks, but in the
early '90s, Ford had problems with the EEC and fuel pump relays sticking on
various vehicles. I had a 1991 Ranger that it took me nearly two winters to
figure out what was draining my battery overnight, but only during the
winter seasons would this happen. When it was warm, the truck would start
normally, which is what caused all the confusion. As soon as it turned
cold, the battery was dead every morning. Turned out to be the EEC relay
sticking in the cold weather. Both relays cost me $20 each and I replaced
both of them at the same time. The problem never came back after that.
I really couldn't tell you where the relays are located on your truck. Mine
were underneath the distribution block, under the hood on the right fender.
the procedure on the fuse box may be your problem. You have to pull ALL
fuses, including the ones in the power center under the hood. THEN pull the
wire to the under hood light (if there is one). THEN, you should have a 'no
drain' indidication. THEN you start putting the fuses back in one at a
time. Remembering that the one for the interior light is going to set it
off 'cause the door is open. Do it last. When you put a fuse in that
lights your light back up, then you have found your suspect circuit.
Remember also, to have the alternator disconnected all the time. It will
(even a good one) sometimes show a full draw with a test light, but it won't
be enough to hurt.
Pull the power door look relay
As for chgarging, unless the battery is very low on charge, severly sulfated
plates, or there is major short pulling lots of amps, the voltage across the
battery terminals should read very close to 13.5 at an idle. At 2,000 rpm
with a load on the system it should stay above 13.5 to as high as 14.5
volts. At max output ie with a load bank on a charging system tester it may
drop down to around 12.8, but shouldn't go any lower again at 2,000 rpm. I
dont understand what you mean by "Turned on the lights and heater and revved
up to 2000 RPM - didn't go above 0.40 volts " does this mean the reading
you got across the battery terminals was only 0.40 volts? If so I would
suspect some major corrosion on battery terminals, or where ground cable
connects to frame/engine. Fords will typically shut down if voltage falls
below 10.5 If it still runs with that reading then the alt is doing its
job(after all the battery is basically just along for the ride after the
engine starts), you got corrosion or bad connection. Remote possablity is
one of the bus bars in the battery is cracked.(bus bars connect plates to
terminals). It may be new, but a human still manufacturered it and as such
is subject to failure right out the gate.
As for chgarging, unless the battery is very low on charge, severly sulfated
Well, I am not a mechanic with 40 years experience, but I have had
considerable working with "dead" batteries that were not really dead
The first thing you must do is determine that the battery posts are clean
and that the clamps are clean and tight.
That does not mean just looking at them, either. That means taking the
clamp off the post and cleaning both the post and the inside of the
clamp until they shine.
Then you must check where the ground is grounded to the frame. They do
sometimes corrode or work loose.
Then you charge the battery or start it with a charger in start mode.
Either run the engine or the charger until the battery is fully charged.
Go to the house and drink a cup of coffee, or something to let the
battery get to its normal state.
Then after you shut down the engine or the charger for several minutes,
put a real load meter on it to see if it will take a load. That means a
real heavy duty load meter.
You can get a reading of 12.5 volts and still not have a battery that
will take the starting load. The load meter is an essential test
because it will tell you if the battery can take a starting load.
Until you do those things, you are putting the cart before the horse.
If the terminals are corroded or loose, if the battery is faulty and
will not pass the load test, you will waste hours looking for a leak
that is not there.
With the equipment I have on my farm, I go through this a couple of
times a year and cure it with the clean clamps and posts thing.
As for the "I can't find my test light", what the hell are you talking
about? You can find a test light in any auto parts store in the country
and they are cheap.
If we do not wish to lose our freedom, we must learn to tolerate our
neighbor's right to freedom even though he might express that freedom
you said that a box was on the door lock switch..
disconect the door wireing and see if your power drain stops
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I wondered that myself. I had a Delcotron alternator short out a diode
and it was dead as a mackerel in the pan, until I took it in a got it
fixed. (I had machined the case to make it fit where a Prestolite had
been and didn't want to mod another one, so rebuilding was best.)
S. Barker wrote:
Actually, the diodes in the alternator can become "leaky", and eventually
run down the battery, or cause other problems. One of my mother in laws new
cars had a problem that would cause the battery to be weak or dead after the
car sat for a few days. (Didn't happen very often, so had the infamous
"intermittent" signature.) I was driving it one evening, and noticed that
under certain driving conditions, the alternator light would glow very
dimly, almost to dim to see, even at night. Turned out that there was a bad
diode and the diode got worse with load on the alternator. Convincing the
dealer to repair or replace the alternator was another hassle.
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