I can’t think of a way to do it that does involve putting an ammeter in series with the battery and pulling fuses one at a time. But that’s because I’m just a dumb engineer. Probably a real car guy will show up with a much easier method.
You are reversing the meter leads somehow when you take the two readings...
I don’t know about ford specifically, but most newer cars and trucks don’t like to have the battery disconnected. It resets the computer.
Try Glove box light (not shutting off when closed).
Is that with the engine off or running? You need more like 14 volts with engine running.
You have an electrical problem, it has nothing to do with brand name.
1. Be not afraid.
2. You can stand in the puddle barefoot and not get a shock.
3.Putting the meter in series is not telling you anything aside from battery voltage
4. Put the battery cables on the battery. Start truck and jump if necessary.
5.Now read battery voltage from battery plus to battery minus. Should read 13.8 +/_
6. If it reads 13.8 alt is charging.
7. If its charging now you can disconnect battery, put a test light in between battery cable and battery- doesn’t matter + or -
8. Turn dome light override off first. Pull fuses one at a time until battery light goes out.
9. A bright says there is a draw....and a dim light is ok for clock, etc.
If you have only the positive cable connected to the battery, and the negative cable floating in the air, then you take your voltmeter and touch between the negative cable and the negative battery terminal, you should be reading 12.76 volts if the Negative (black) meter lead is on the battery and the positive (red) meter lead is on the negative cable. If you have the black meter lead on the negative cable and the red lead on the negative battery terminal, you’ll read the same voltage, but reverse the polarity, so it will be -12.76.
What’s the issue? Sounds normal to me. If your friend’s battery keeps dying, and it is over 3 years old, it’s time for a new battery. they make them so cheap these days that you’re lucky to get three years out of a battery. If it is a sealed type, replace it. If it is a non sealed type, pry open the caps and make sure the cells are filled with DISTILLED water to the indicator mark, or at minimum so that all of the plate material is under water by at least 1/4”.
“When I hook up the posi and jump my meter from the neg term to the neg cable, I get -12.76.”
Not exactly sure what you’re doing here, but if you have both battery terminals connected, you should measure around 12 volts from the pos terminal to any metal ground on the vehicle and 0 volts from the neg terminal to any metal ground point. If your battery is going down due to standby current, you’ll need an ammeter. But check the obvious first, such as courtesy lights that aren’t going off, etc.
You should have voltage in any car with a brain or clock, what you need to check is current. Anything north of 1A with key, lights off(including the courtesy lights) you shouldn’t be over 1A.
The terminal voltage tells us very little. It is an indication of the state of charge, not current draw.
What’s the current draw from the battery at one of the terminals?
It’s not going to be zero, but 3-5 mA would be normal to feed the memory in the radio. If you’ve got more than 100mA you’re going spelunking.
Battery is new, alt is new. I am going look for an ammeter to borrow tomorrow night.
Ford’s usually have the starter solenoid on the firewall unlike lowly GMs which use the solenoid to make the electrical connection as well as shoot the Bendix out to the Flywheel teeth.
I don’t know how a 98 does it but usually, there’s a big cable that goes to the solenoid from the battery positive, this is for the starter. There’s another smaller cable on the positive battery terminal or on the battery side of the solenoid that powers the rest of the vehicle and also gets the charge voltage from the alternator. You could try to disconnect the positive from the alternator; maybe it has a shorted diode or something?
As someone else mentioned, you can also pull fuses until the draw goes away. Before EFI, you would start the engine and then pull the negative from the battery, if it died, the alternator was toasted, nowadays, that has the possibility of taking out the EFI which is no fun.
The radio has a parasitic draw to keep all of your pre-sets. How old is the battery? You would be amazed at what a bad battery presents as.
Let us know what you find?
Any kind of electrical aftermarket accessories go to the top of the suspect list.
I love how freepers help one another.
Main power relay may not be de-energizing, or bad diode in the alternator.
You could get a wiring diagram and inspect all the wires carefully for wear and a short, especially under/outside the truck, if she’s been using it as truck and not a fashion accessory.
But here’s the real redneck solution:
I have a `95 Merc. Sable and had the same problem. It has been a fine car otherwise.
The above was too much work so I just crushed all the bulbs I didn’t think I needed with pliers. Took about five minutes.
No more battery drainage and I drive the car pretty much in the daytime now. Have someone hold your beer ... I estimate its FMV by how much gas is in the tank, but it’s still my go-to sled.
A lot of the answers are good here but I like the clip ammeter idea where you place it around the negative battery cable to see if there is a huge draw. I worked for Advance Auto Parts for a few years and back in 2012, someone brought in a 1980 Cadillac and I checked it out and he was drawing 23 amps with everything off. I’d say there is a short somewhere, electrical problems can be tough. I once had a 1994 Ford Explorer where mu taillights didn’t work and the whole system needed rewired because they could not find where the short was. I was $800 poorer.
A close to dead battery will read 12 volts because there is no load on it. Try jumping the battery. My wife’s car sat in the garage from Jan to the end of Feb. The battery was dead and had to be jumped.
If you keep sparking the battery you will be sure to blow the computer.