YARDofSTUF

So I have a multimeter and a drain and I've got the fuse box open, what should I set the multimeter to?

I see 2 spots of metal on each fuse so i assume i test from there, but not knowing hwo to use the multimeter i've gotten no reading each time.

Lunch Box

Do you want to test the fuse itself to see if its good?

If so set the multimeter to the "ohms" setting - this will let you test for continuity. If the needle moves then you have a complete circuit thru the fuse - if not then you don't

i know this is ugly and basic and probably an abuse of a multimeter but it should work - i use mine this way to check to make sure my truck's block heater and it's cord are good at the start of the winter

shoebox

This is with the fuse removed from the fuse box. Meter must be set to read ohms. You should get the same reading on the meter as you do when you merely connect the leads together. Don't ever check for ohms on a live circuit. Check for voltage, first. You cannot measure ohms in the presence of voltage. The reading would be meaningless.

YARDofSTUF

So with the fuses in I should read voltage?

YARDofSTUF

I have a commercial electric one, Is Voltage the V with the ~ over it?



EDIT: Also, after removing the radio fuse should the clock still work?

Z28SORR

~ this is AC V you want -- DC V. Should be two seperate selection or a toggle switch. Measure one side of the fuse to ground(metal part on the car), when the other side. Should get about 12 V on one side with the fuse out and on both sides wiht it in. Make sure that the accessory your checking is turned off.

YARDofSTUF

Thanks i was deffinately doing it wrong LOL

Injuneer

The radio has two power supplies... one switched and one unswitched (for station memory, clock).

If I read your original post correctly, you appear to have a "drain" on the system that you are trying to locate. Is this correct?

If so, you need to look for current (DC amps) in the circuits, not voltage or ohms.

Or maybe I interpreted your post all wrong.

YARDofSTUF

You got it right, so what setting should it be? I have teh --- it also has a straight line above that, is that the right one?


Thanks guys, sorry for the 3 or 4 posts on this lol

YARDofSTUF

OK got some results

a 20 fuse labeled TAIL and a 30 fuse labeled CTSY teh CTSY should have a 20 according to Chiltons. The readings were low but thats all thats drawing from teh fuse box(assuming i'm doing this right) what is the tail and CTSY and can i unplug the fuses without a driving issue?

Injuneer

The fuse ratings are the amps that will melt the fuse and cause it to open the circuit. You can't "measure" the fuse rating.... you aren't going to see "20" anythings on a 20-amp fuse. At least not probing it with a multi-meter.

"Tail" is the tailights. "CTSY" is the interior lights. But on my 94 the interior lights, radio, power trunk release and a couple other odds and ends were all on the same fuse. But they make changes from year to year.

Try it one more time.... EXACTLY what are you trying to do? Are you trying to locate a source of power draw on the battery when the key is in the "off" position?

YARDofSTUF

Yeah key is off, and i'm trying to find a draw, tail and CTSY are the only ones showing any readings


the point about the 20/30 thing is that the Chiltons the listed one shows a 20 in the book and the number ritten on teh fuse is 30, i didnt get a 20 or 30 in the meter, jsut wondering if it should be replaced with a 20 fuse?

Injuneer

Your fuses should match the values shown on the diagram on the cover. You might want to check and see if that's the same as shown in Chilton's. Sometimes they use one picture to cover a wide variety of years, and there are subtle differences between the models.

I wouldn't worry about a 30-amp fuse being in a spot where a 20 is called for, at least not at this point in time... it isn't contributing to your problem.

YARDofSTUF

Well I unplugged the tail light fuse after driving it to fully charge the battery.


Is there any fuse that I should not unplug?

Deckstripes

That 30 amp fuse could be a clue that you're on the right track. Obviously it's blown a fuse and been replaced by somebody else. Could be that they didn't have a 20, or could be a 30 fuse kept it from blowing, and now you're chasing the root cause of the blowing 20 fuse.

Between my cars, and my friends, I've un-cheesed alot of phantom electrical stuff. When you see a heavier fuse, look deeper.

If you want to probe the circuit for the source of the draw, a voltage drop test works great. Set the meter to DV volts and check between points on the live circuit. Actually place the red and black leads on the same piece of wire. When you get a reading other than 0, it's because there's an electrical load between the probes. Load reduces the voltage. And the "load" is probably your short, or bad switch, or bare wire, or whatever the root problem is.

Example- voltage drop across a light socket. If you have a 2 wire socket, place each test lead on a wire. With the bulb lit, you will see a voltage drop (a reading on the meter). With the bulb off, meter should read 0, because there is no electric load. But if you see a little voltage drop, then it's because the socket is a little bit shorted out. Good Luck