Parasitic drain
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Junior User
Joined: Jun 2007
Posts: 82
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From: Pennsylvania
Parasitic drain
What is the procedure in finding a parasitic drain thats killing my battery in my 86 B2?
I'm getting tired of recharging the battery so often. I'm afraid that I'm gonna cook the damn thing.
Thanks....
I'm getting tired of recharging the battery so often. I'm afraid that I'm gonna cook the damn thing.
Thanks....
Postmaster
Joined: Oct 2003
Posts: 4,516
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From: SoCal
Yeah. it's pretty simple.
Everythiing on your B-2 is powered from fuse links.
You might want to remove the 4 fuse link wires from the starter relay & see which one kills the light.
One of these fuse links feeds the alternator & if theres a shorted diode in the alternator it will suck the juice out of the battery & the alternator will probably feel warm to the touch.
Everythiing on your B-2 is powered from fuse links.
You might want to remove the 4 fuse link wires from the starter relay & see which one kills the light.
One of these fuse links feeds the alternator & if theres a shorted diode in the alternator it will suck the juice out of the battery & the alternator will probably feel warm to the touch.
Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
Yeah. it's pretty simple.
Everythiing on your B-2 is powered from fuse links.
You might want to remove the 4 fuse link wires from the starter relay & see which one kills the light.
One of these fuse links feeds the alternator & if theres a shorted diode in the alternator it will suck the juice out of the battery & the alternator will probably feel warm to the touch.
Everythiing on your B-2 is powered from fuse links.
You might want to remove the 4 fuse link wires from the starter relay & see which one kills the light.
One of these fuse links feeds the alternator & if theres a shorted diode in the alternator it will suck the juice out of the battery & the alternator will probably feel warm to the touch.
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Junior User
Joined: Jun 2007
Posts: 82
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From: Pennsylvania
I was wondering about the alt. When I rev it up, the battery light comes on, when it idles, it goes back out. Something else to think about.
There is a small business locally that tests these for free. Sometimes they have new ones on hand, but I doubt one for this age of vehicle. Wont hurt to check.
There is a small business locally that tests these for free. Sometimes they have new ones on hand, but I doubt one for this age of vehicle. Wont hurt to check.
Postmaster
Joined: Oct 2003
Posts: 4,516
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From: SoCal
Souns like the brushes are worn, that wont cause a drain though.
If you turn the key on/engine off & the alt heats up theres a shorted diode.
If you turn the key on/engine off & the alt heats up theres a shorted diode.
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Junior User
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I will be checking all we discussed after I get the battery up again... I will keep you posted. Thanks for all the info.... 
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Postmaster
Joined: Oct 2003
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From: SoCal
Originally Posted by Fordpup
I was wondering about the alt. When I rev it up, the battery light comes on, when it idles, it goes back out. Something else to think about.
There is a small business locally that tests these for free. Sometimes they have new ones on hand, but I doubt one for this age of vehicle. Wont hurt to check.
There is a small business locally that tests these for free. Sometimes they have new ones on hand, but I doubt one for this age of vehicle. Wont hurt to check.
Looks like a charging problem, instead of a drain.
Sounds like a good idea to have that shop check the charging system.
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Junior User
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From: Pennsylvania
I will be looking into new brushes and diode for the alt. On another note about the drain, the battery that I installed had been sitting in my shed for about three weeks before I installed it in the Bronco. It was still charged up enough to start and drive it around my yard for about a week, then I parked it until I can get up the money for more parts. After one week of no starting or running it, the battery went down again. Thats why I was looking into testing for a parasitic drain.
Postmaster
Joined: Oct 2003
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From: SoCal
Yeah, a set of brushes should take care of the charging problem.
Sounds like the battery might have gone dead from sitting around & from not charging. But the light bulb test will tell you real quick if it IS a drain.
I've driven my different Fords a LOT of miles & never had an alternator problem.
Seems Ford alts are pretty bullet proof, so you might even want to look for one off a wrecked Ford at the bone yard. If you're going to replace the brushes yourself disregard this.
Odds are it will last a good long time, and the folks at the wrecking yard can probably tell you which years/models used the same alt as yours.
Sounds like the battery might have gone dead from sitting around & from not charging. But the light bulb test will tell you real quick if it IS a drain.
I've driven my different Fords a LOT of miles & never had an alternator problem.
Seems Ford alts are pretty bullet proof, so you might even want to look for one off a wrecked Ford at the bone yard. If you're going to replace the brushes yourself disregard this.
Odds are it will last a good long time, and the folks at the wrecking yard can probably tell you which years/models used the same alt as yours.
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From: Pennsylvania
Well, looks like I found the start of my drain problem... there is a yellow heavy gauge wire that starts from the solenoid on the pass. fender, goes across the rad support, plugs into a connector on the other fender. Right where the 2 wires plug together, the wire was actually smoking when I connected the battery. I disconnected the battery, took the yellow wire off the solenoid, the terminal did not spark when I reconnected to the battery. That also took all power from inside the vehicle.
Here is where I need the most help. Where the 2 wires connect on the drivers side fender, the wire goes 1 to 4 wires, with fuseable links on 2 of them. Does anyone have any idea where I should go from there? Could a bad fuseable link cause this kind of power draw, enough to smoke a wire? I really could use some direction from here.
Any master electricians here? Need input and/or a schematic for the old girl.
Many thanks.
Here is where I need the most help. Where the 2 wires connect on the drivers side fender, the wire goes 1 to 4 wires, with fuseable links on 2 of them. Does anyone have any idea where I should go from there? Could a bad fuseable link cause this kind of power draw, enough to smoke a wire? I really could use some direction from here.
Any master electricians here? Need input and/or a schematic for the old girl.
Many thanks.
Postmaster
Joined: Oct 2003
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From: SoCal
What appears to be the same circuit on my 87 is wired thusly:
Fuse link C at the starter relay (black with orange stripe) is wired to a connector on the drivers side fender.
The connector is wired to a 4 way splice with 2 fuse links.
Fuse link D (black/orange stripe) feeds horn/cigar lighter/headlight switch.
Fuse link E (solid yellow) feeds the ignition switch.
Dont worry about these fuse links.
The other 2 wires in the splice (black/orange & yellow/white)connect to the alternator.
Remove them from the alternator & see if you lose your drain.
My guess is a shorted diode in the alternator.
Fuse link C at the starter relay (black with orange stripe) is wired to a connector on the drivers side fender.
The connector is wired to a 4 way splice with 2 fuse links.
Fuse link D (black/orange stripe) feeds horn/cigar lighter/headlight switch.
Fuse link E (solid yellow) feeds the ignition switch.
Dont worry about these fuse links.
The other 2 wires in the splice (black/orange & yellow/white)connect to the alternator.
Remove them from the alternator & see if you lose your drain.
My guess is a shorted diode in the alternator.
Last edited by 87 XLT; Nov 4, 2007 at 01:11 AM.
Thread Starter
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Junior User
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From: Pennsylvania
87 XLT, I will be checking that this morning. You said the wire from the relay is black/orange, so the p.o. must have had a problem cooking that wire too cause it was replaced with the yellow wire I mentioned. Should there be a fusable link in this line as well? I found where the yellow wire was spliced into the black/orange wire and crimped. Makes good sense to me. 18 gauge perhaps??
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Junior User
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From: Pennsylvania
Hey 87, you were right on the alt diode diagnosis. I unplugged the diode pigtail and the drain quit. No smoking from the wire either. I need to replace the diode, install a new fusible link in the yellow wire that used to be black/orange, and replace all the wiring that got cooked.
I will let you know how it turned out. I will hopefully be doing this soon, but seeing as my wife is disabled, I have to make sure she is taken care of first.
Thanks for the valuable information. You know your stuff.
I will let you know how it turned out. I will hopefully be doing this soon, but seeing as my wife is disabled, I have to make sure she is taken care of first.
Thanks for the valuable information. You know your stuff.