mystery battery drain

[Zapstrap]

First, thanks for this cool feature, I promise not to abuse it!

My wife's 89 Ranger 4x4 is having a mysterious battery drain.

I have put a multi-meter between the neg post and the neg terminal. Pulled all the fuses, nada. Pulled the ECM, nada. Pulled every relay I could find, nada.

Just removed the two smaller wires from the solenoid, and voila, found something... problem is, I have no idea what I just found! All I know is the meter reads 0 when I disconnected them.

Anyone have any ideas?

Thanks eh!

 

[Earl43P]

Alternator has bad diode (rectifier).
Very common.

 

[Zapstrap]

Alternator has bad diode (rectifier).
Very common.

Thanks for the reply Earl43P.

I'll pull the wires from it after lunch and check.

Also, I eliminated the solenoid from the cursed objects list...

 

[Zapstrap]

the mystery deepens

Ok, disconnected all of the leads to the alternator and the problem is still there.

The only hint I have right now are the two wires with fusible links that come from the solenoid.

It's like there is a completely closed circuit somewhere.

I'll try and get some pics up...

 

[Zapstrap]

OK, FWIW, here's a couple of shots of the wires I spoke of...

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What I find odd is that pulling all of the fuses, disconnecting the alternator and the ECM made no difference at all.

If this was a dead short, all that would be left of the truck would be a burnt out hulk, no?

 

[adsm08]

Wait, are you testing voltage?

 

[Zapstrap]

Wait, are you testing voltage?

Yes.

 

[adsm08]

You know that a parasitic draw test is supposed to look for amperage, right?

If you have the positive lead on the body and the negative lead on the battery negative you are doing a voltage drop test, which is basically looking at how much voltage is lost on the connection you bridged.

 

[Zapstrap]

Are there any hidden fuses or circuit breakers that I might want to know about?

And this may or may not have anything to do with this but...

When I bought this truck, the previous owner had removed the guts for the power locks and windows. They left the door lock solenoids in but took the window regulator motors out.

I noticed whenever it was raining, or even really humid, the door lock solenoids would start to lock and unlock all by themselves. We put up with it for a little while but after being locked out of the truck, that was it, I went fishing for the cause. I had already tried to find the fuse for them, but couldn't find anything. So I took the door panels off and simply disconnected the plugs from the solenoids. Ah, problem solved... or maybe not?

This makes me wonder if the spirit of door locks past hasn't come back to haunt us!

 

[adsm08]

Get out under the hood and unplug the door harnesses, see if it helps you draw issue.

 

[Zapstrap]

You know that a parasitic draw test is supposed to look for amperage, right?

If you have the positive lead on the body and the negative lead on the battery negative you are doing a voltage drop test, which is basically looking at how much voltage is lost on the connection you bridged.

Um, nope, didn't know that...

I was simply following the advice I found on this thread, http://www.therangerstation.com/forums/showthread.php?t=42331

As a matter of fact ,it was this answer that got me to sign up today.

I am just learning as we go here.

 

[Zapstrap]

adsm08, you sir are to be given a huge attaboy, a pat on the back and a nice cold one.

It took a while to find the little offenders. (Like who would have thought the door harness plugs would be behind the headlight assemblies!) But there they are... Disconnected them and voila, no more power draw.

Of course, that means there's something else wrong in there somewhere but hey, since they aren't going to be used any time soon, I guess it doesn't matter....

Thanks again eh!

 

[adsm08]

The only thing to watch with just leaving the doors unplugged, since it is the wife's truck, you might lose the door speakers. I am not 100% sure how those are wired that year.

 

[Zapstrap]

...but that's not all!

Ok, we got it started. We live way out in the middle of nowhere, so getting it going is a huge thing...And you guys were the reason I got it fixed at all, so thank you for that

As for the root cause of the problem, it looks like earl was right, the alternator is shot. It's pushing out 15.4V. A tad too high there eh? I suppose I could dig in to it and try to replace the blown diode, but if for some reason I can't do it, then we're stuck up here. My old F-250 is currently off the road so the Ranger is our only driver right now...

So... it's an hour and a half to the nearest auto parts store. I don't imagine it would hurt anything to drive it down there, would it?

Oh and as for the door speakers, they weren't in there when we bought it so they won't be missed anyway, haha...

 

[adsm08]

15.4 volts can damage the battery and in extreme cases it could start a fire.

Postin' from teh Galaxy