I have had trouble with Battery gping dead on my 1991 F150 4.9L . I have a CONSTANT CURRENT DRAIN OF 300 mA (.3 Amps) This to me seems alittle high for the EEC !! ANYONE KNOW WHAT THE CONSTANT CURRENT DRAIN SPECIFICATION IS ???
John

 

usually .03 or .05 is ok. i can tell ya anything over.09 like .10 is too much! might have to pull fuses till ya get to the right source.
good luck some shorts can't be found over night.

 

Hook a test light up like this




And then pull fuses till the test light goes out. If you have a problem, it will glow fairly bright.

If none of the fuses kill the light, then pull the alt wire off and see if the light goes out.

 

Thats a nice diagram you got--I connected my Fluke DVM like that on the 10-Amp scale and the steady/constant current was .3 Amps with only the power to the computer...we disconnected everything at the starter relay-we also had disconnected the Alternator.
Now in messing around I swapped the relay for the computer from another truck still had the 300-mA. but more messing and then we didn't seem to have the 300-milliAmps --
--but it was getting late so I quit for the night.. I'll post what success we may have.
I thought in my head that current to keep the computer active would have to be less than 10-mA. --- that the 300-mA I have been getting was out of line. John

 

if it has one, check the light inside the glove box and see if the switch on the glove box door shuts it off. My mother's (God rest her sole) '89 Ranger had a problem of the battery dying after a few days of not driving it, and that is where I found the problem. Originally thought it was a weak battery, bought new one, still had the same problem until I found the bad switch on the glove box light. I removed the bulb instead of replacing the switch and no more problems. There is something staying on that should not be. Good luck.

 

Yes the glove box light can be an elusive one--My brother called to have me jump his Escort that went dead and it was the Cooling Fan switch had stuck.
We no longer have the 300 mA. Current drain its now less than 10 mA. We were switching the ECC relay which is where the Drain was on that line - the relay was quite corruded on and around its terminals----we had cleaned it up and then as we were switching things around / trying different things --- NO MORE PROBLEM THE CUURENT DRAIN WAS GONE ??? At least I hope it is -- makes sense so will see how it goes---Thanks Everyone for IDEAs. John

 

I have a current drain on my batteries as well. I ran the test as per the diagram on the fuses inside the cab. All I got was one fuse dimming the test light when pulled, but not actually putting the light out. I even pulled the 3 circuit breakers. I haven't yet tested the fuses under the hood. My owners manual says to disconnect the battery before replacing any fuses in this box. So, dumb question here, can I do the diagram test light test to these fuses as well as the same way I tested the interior fuse box? Also, I did in fact pull "an" alternator wire ( the large boot covered one that has a 10mm nut) and the light stayed on. Can the "other" wire (the one that has a black plastic connector I couldn't budge, that appears to be the brushes connection) be removed, and how with how much force, as it didn't appear as though it wanted to be removed...lol...stubborn. Also, what about the relays in the box under the hood? Could they be faulty but not toatlly defective, and how do I check those? And last but not least, how do I use my multi-meter to determine how much of draw I am experiencing (sorry, another dumb question)

 

When I tested my Alternator I wound up removing it and than working the Regulator plug out --- but it waqs okay. My draw was the Relay in the BOX next to the Air Filter -- it was corroded arounf its terminals -- I'm not really sure if that what caused the leage current -- but after I cleaned it my drain was gone --- but the terminals were still kind of crusty so I replace it.
To check the CURRENT drain I used a FLUKE multimeter which had a 10 AMP scale -- using a procedure similiar to the test light method.... " I had the battery and everything connected -- I then connected the Ammeter from battery terminal to battery cable and disconnted battery but left meter accross the terminals not breaking the connection and then reading the Drain current " ..
If you have a meter with a fuse protected Amp range it should be fairly safe todo with out damaging your meter...
I had also been using those battery disconnect terminals because of the drain so it was easy to disconnect and maintain the meter in the circuit.. My constant drain was about 300mA. which would make a small lamp glow dimily---

 

Thanks John. I'm trying to visualize the draw test as:
(1) Have the battery connected.
(2) Then connect the ampmeter to the battery terminal (post) "and" the battery cable end (still connected to the post?)
(3) Then disconnect the "other" battery cable end from it's post to break the battery internal connection?
(4) At this point there should be an ampmeter lead connected to a battery cable end and post that are still connected?
(5) Then read the current draw by leaving the "meter" across the "terminals" (which terminals here?)

Is a "terminal" in your description the same as a battery terminal post or are you referring to the leads of the ampmeter as the "terminals"?

When you say "disconnect" the battery, do you mean both battery cable ends on the positive & negative terminal / post?

When you say "leave the meter across the terminals" do you mean as in connected to a battery cable end that is still connected to the terminal / post?

Sorry I am not "getting" this, I guess I have a difficult time visualizing the procedure. But I am confused as to whether the battery cable ends remain attached to the terminal(s) / post(s) and the ampmeter lead(s) are connected to both at the same time or if the battery cable end is removed from the terminal /post as you do when you use a test light? can you explain it again as I am not perceiving the steps.

 

If you put one test lead on the side of the cable clamp and the other test lead straight up on the top of the battery terminal you can lift the cable clamp up (and over/around) the test lead on the battery (disconnecting the battery) while still maintaining contact with the proper test leads.

 

Thanks McGuyver. So, if I follow you here, I will be holding the cable end in one hand while I hold the test lead on it's battery post and lift the cable clamp straight up with the lead in it's open center while I hold the test lead firmly on the battery post and then view the reading on the multimeter while I'm holding the cable clamp with one hand and the test lead pressed on the battery post with my other hand. Have I got it now? Sorry for the confusion on my part, but I guess sometimes actually seeing it or doing it is clearer to me. Thanks again.

 

63Fairlane500

You didn't say what year truck you are working on, but it sounds like a fairly late model since you have a fuse box under the hood. What I would do is try to follow how the power is distributed in your vehicle.
Of course the power is going to be coming from the battery positive, but follow this down to the starter relay. If it's like most Fords, there will be a bunch of smaller wires connected to the large post on the battery side of the starter relay. See if there is one going to the alternator output, one to the fuel injection relay, and maybe one to the other fuse box under the hood. This may not be exactly like it's routed, but when ever you find a point like this, take the wire off and see if the light goes out. This way you can eliminate major branches of the electrical system, and narrow it down more quickly.

 

Thanks Franklin2

Sorry, it's a 92 F250, 7.3 Diesel, with two batteries. I am concerned as to whether or not I can "safely" pull fuses from the power distribution box under the hood to see if the test light goes out, as my owners manual says to disconnect the battery when you're just replacing a fuse in this under hood "fuse box". However, I can't see how you can test for a circuit current draw without pulling fuses from this "other" box one at a time until the light goes out. I don't see any difference bewteen this box and the one in the cabs dash panel, even if there are some 50 amp fuses and some relays (which I also suspect), but is still basically just another fuse box. The last step mentioned in your previous post with the diagram, says to pull the alternator wire. Is this the "large" wire that is attached with a 10mm nut or the wire that seems to be the regulator or brush set wire? I removed the large wire with the test light hooked up and the light didn't go off. I attempted to remove the smaller wire, but when it was not easily forthcoming, I backed off thinking I might damage it if I applied too much force, although it would have to be removed if the alternator comes off for any reason. Perhaps theres a "trick' to removing the smaller wire connector that I haven't figured out. It appears to have a "tab" that has to be manipulated in order to remove it but I couldn't readily determine how it is freed. Any suggestions?

 

I don't have much experience with the newer alternators, which must be what you have from what you are describing. The heavy wire would be the output, and the smaller wire would either be a wire from a 12 volt keyswitch source to bring the alt "online" or it can be a remote voltage sensing wire that the internal regulator uses to monitor the electrical system's voltage level.