dead battery/electrical problems with 1990 F-250

Don't use a voltmeter for parasitic draw testing... An ammeter is the appropriate tool for this...

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.

Good luck, Sharky

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.

If you use an ammeter you can use a bit of instinct and judgment to narrow down the culprit. Are you hunting for a 5A relay or the bulb in the glove box ?

Bill

On Tue, 11 Dec 2007 22:40:11 -0500, UseNet Reader rearranged some electrons to say:

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.

Whitelightning

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 more clear?

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....

you said that a box was on the door lock switch.. disconect the door wireing and see if your power drain stops

-- Message posted using

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 after all.

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.

CSSJR

If the alternator diodes are shorted out a little, it may be enough to drain the battery. I had a moped that had such a problem.

"If the alternator diodes are shorted out a little:)"

Al

is that like being a 'little' pregnant?

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.