If the fuse is blown in the meter, then there was current flow for too long. Most meters will read something like 10Amps for a max of 15 seconds. So trying to find a draw using a meter in series like this is not always the best method. If you are sure this isn't just a failed battery, what we will usually do (and I know this is an older vehicle), is to first make sure we get all the normal current draw on the battery shut down, so interior lights if you can latch the door latch with it open to get the interior lights to shut off, or if it has a door switch. If there is a lamp under the hood, unplug that, any glovebox light that may be staying on, Then check to see how much current draw there is on the battery. Since this is an older vehicle and doesn't have a bunch of modules that need to power down like modern vehicles (thankfully), finding the draw shouldn't be too difficult, but once you quickly take a reading of the current flow with everything off, you can go through the fuse box and with the meter set to DC volts, you can check each fuse for a millivolt (mv) reading.
Any fuse that has a reading except 0.0mv has some current flow on it, it will be a very low mv reading, but what you are doing is checking for voltage drop on that fuse. For there to be any voltage drop on a fuse there has to be current flowing through that fuse. This is can quickly lead you to the fuse and circuit that is causing the draw. Im not sure what kind of multimeter you have, if it has a mv setting or just auto ranges when set on DC voltage.
You can also put a test light in series with the negative cable, most 12v automotive test lights will pull about 250ma of current depending on the type, if its an LED test light they will only pull about 40ma maybe.
In your case you are probably safe with pulling fuses because there aren't large networks of modules to worry about. You do have an ABS module, Anti-Theft module, possibly a keyless entry module, Air bag module, etc. Im just reading off what I see in the wiring diagrams for the 1993 Ford Truck E 250 Van V8-302 5.0L, if that is the correct model.
If its a different model and engine let us know, or just post the vin number and we can look it up by that.
Then when you find the fuse that is suspect, we can pull up the wiring diagrams for it to see what it on that circuit.
(This is just an explanation of why we are checking for battery draws this way now.
This more technical method we're using along with current Amp clamps which clamp around the battery cable to read current flow is due to the amount of control modules in vehicles these days, we try not to pull fuses anymore because reinstalling them wakes up the vehicles modules and networks causing more current flow on the battery and we have to wait for the vehicle to power back down again which can take a long time in come cases.)
Sorry for the long message.
Here is a guide to help
https://www.2carpros.com/articles/car-battery-dead-overnight
Wednesday, September 10th, 2025 AT 1:37 PM
