FRUSTRRATING ELECTRICAL PROBLEM

[surfink1970]

I am having a difficult time figruring out a problem with my 71. If it sits for more than about a day and a half with the battery connected it goes dead. Ive tried to find any shorts but have had no luck. I've pulled fuses and test lighted and gotten myself quite frustrated. The electrical components are very close to bone stock. The only add on is a tach. The radio was removed long ago. Any thoughts on this would be greatly appreciated. Thanks for taking the time to read my ramblings.

Eric

 

[bert]

Sounds like you are using your test light in series with one of the battery cables. Try unplugging the regulator or disconnecting the alternator and see if your light goes out. A dirty battery case or battery hold down can drain a battery. HTH

 

[jeev]

Check your ignition switch. If it is not operating correctly it may be stuck in the acc. position and supplying power to your EB after you turn the key off? I had the same problem and fixed it with a new ignition switch. Also if this is the problem it is a fire hazard Good Luck.

 

[Broncobowsher]

IF you are using the test light in series (remove the batter cable and put the light in the circut) does the light come on? If so then you have a drain. If not then you might just have a bad battery.

If the light is coming on, unhook the alternator wires. I would guess that you have a bad doide in there. That allows current to back flow into the alternator and run down the battery. The alternator will still charge with a bad diode, just not as good as it should.

 

[BwoncoHowie]

[quote author=Broncobowsher link=board=5;threadid=18401;start=0#msg140864 date=1055185371]
IF you are using the test light in series (remove the batter cable and put the light in the circut) does the light come on? If so then you have a drain. If not then you might just have a bad battery.

If the light is coming on, unhook the alternator wires. I would guess that you have a bad doide in there. That allows current to back flow into the alternator and run down the battery. The alternator will still charge with a bad diode, just not as good as it should.
[/quote]

If it's not a large Amperage draw, your test light in series with the battery cable may not show any signs of lighting. If you use an Ammeter in line with the battery connection it will show a battery drain that is small enough to not make a test light come on. If you definately find a drain, the other posts about eliminating the alternator out of the system, then re-test with the Ammeter is a good place to start.

Caution; Have your key off and the battery ground cable disconnected while removing, replacing or servicing any of the alternator connections.

BH

 

[Rustytruck]

In a Bronco you dont have too many live circuits so remove the fuzeable links from the starter solinoid when you use your test light. also use the light on the positive side and not the ground side of the battery. Alternator or brake light switch is the best bet.

 

[surfink1970]

Thanks everyone.

Eric

 

[bert]

So, were you able to track down your problem?
What did you find?

 

[Pigpen74]

It's possible your voltage regulator could be fried. Happened to me a few weeks ago, after a week of pulling my hair out trying to figure out where the current draw was coming from. Replaced it with one from NAPA, and didn't have anymore problems. Then I circumvented the whole situation two weeks later by doing the 3G upgrade.

 

[moabers]

I don't mean to get off track with this, but I am wondering why you would check for a drain at the positive and not the negative. I have had a few people say that, but I haven't heard an explanation why, so please elaborate.
All the training, classes, repair manuals and textbooks that I have experienced indicate it should be tested at the negative terminal. Just for the measurement sake of a drain, with the vehicle off, the only source of current is the battery. Measuring current at either the positive or negative terminals will give identical readings, but reading it at the negative terminal reduces the possibility of sparks.

There is my explanation of why it should be tested at the negative, please tell me where and why I may be mistaken.

Thanks,
Dave C.

 

[bert]

When disconnecting the battery the Neg side should be undone first and hooked up last. Same thing with jumper cables, only hook the Neg jump cable to the dead vehicle last and not to the Neg battery terminal, it should go to an engine ground.
Using a test light to check for a current drain will work on either side of the battery.
If you are using an ampmeter, hook it on the Neg side. By doing so you are able to measure a drain on the battery through the case or hold down by simply undoing the Pos terminal and reading the meter. My 0.02

 

[sbottone]

I have the same problem if my battery is left connected. Could somebody please explain a little more as to what to do step by step. For example I am a bit confussed as to where you put the tester. Sorry I am knew at this stuff so please really go step by step.
Thanks SETH

 

[Bart]

First recharge the battery. Then remove one of your battery leads. Then connect on end of a test light to the battery cable and the other end of the test light to the battery post that you just removed the cable from. There seems to be some decision as to which lead to remove. I didn't know there would be any difference. Anyway, if the light glows then start removing fuses one at a time until the light goes out. If this works the last fuse you pulled will be the circuit that has the battery drain. If after all fuses have been pulled and replaced one at a time then disconnect (one at a time) the alternator main battery lead, field, regulator. Another area to look at besides the brake light switch is the headlight switch and heater fan motor. The head light switch is not easy to remove so safe it for last. Ignition switch is another possibility but it's like the light switch. Good Luck

 

[sbottone]

thanks for the step by step info

seth

 

[rstgermaine]

My buddy had the same problem on his heep and it turned out to be his altinator - the diodes were allowing current to back-flow when the engine was off and the battery was getting drained.

The easist way to check is to remove either battery cable, then, with every source of current draw off, measure the resistance between the neg and pos batt connectors. Should be around 10k to 15k ohms. If less, start pulling fuses and disconnecting circuits until your meter goes to infinity (open circuit). Start with disconnecting the altinator as this should be the only thing in the circuit with everything turned off. Whatever resistance you measur at the battery cables you should also get at the altinator (bat lug to case ground).

 

[rstgermaine]

Oh yeah, I forgot to mention to look real carefully at the wiring harness between the alt, solenoid, voltage regulator, and battery. I had some wires worn through the insulation on my Bronco that caused the same problem. Let us know when you finally find the culprit.

 

[Rustytruck]

I just went through this mess in my motor home and after all was said and done I learned alot, yes if you use a meter or test light through the negative side it will indicate a consumption of current but will not show if you eliminated that problem. you need connection to ground to trace the loop. and remember that the short is carrying its own ground so if you hook your light or meter to the positive side and disconnect or pull the circut you break that link and isolate the problem. If you have it hooked through the ground wire and pull fuses and disconnect stuff it doesnt necessarly disconnect the circut especially if you have multiple areas sucking power.

 

[Bart]

[quote author=rusty truck link=board=5;threadid=18401;start=15#msg142626 date=1055544144]
I just went through this mess in my motor home and after all was said and done I learned alot, yes if you use a meter or test light through the negative side it will indicate a consumption of current but will not show if you eliminated that problem. you need connection to ground to trace the loop. and remember that the short is carrying its own ground so if you hook your light or meter to the positive side and disconnect or pull the circut you break that link and isolate the problem. If you have it hooked through the ground wire and pull fuses and disconnect stuff it doesnt necessarly disconnect the circut especially if you have multiple areas sucking power.
[/quote]
hey, Rusty Truck, I'm always interested in learning more. Please clearify something for me. I quote you "you need to connector to ground" Connect what to ground?? Disconnect which battery lead?? Don't disconnect battery?? Thanks in advance.