IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Auto Tech => Topic started by: daveismissing on March 01 2011, 07:42:55 PM
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Since we have some F150 expertise inhouse:
I have a wire that comes from the ignition switch and is supposed to provide 12v to the
alternator. It does that but when ignition is off instead of being an open circuit there is some resistance to ground. This inturn causes the alternator to drain the battery overnight.
Temporarily (yah right) solved it with a relay. Its gotta be the ignition swich contacts?
Anyone seen something similar?
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I would guess a bad diode in the alternator, myself
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Was my first guess too, after the battery.
Could not get an OEM alt, so I did put in a rebuild. Same thing.
Could be a shitty rebuild? Supposed to be decent (local)
Was already a rebuild in there, one of the really crappy ones that whined like a B*
Was at least happy to have that noise go away.
Also pulled the GEM and disassembled the fuseblock- mint, no corrosion.
Dunno why I'd see a semi-ground (was bloody freezing- don't remember how well I characterized it) back thru the ignition contacts...
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If you've got a volt meter or a test light take the battery cable off and once you establish that it's drawing power then pull one fuse at a time intil the draw is gone. That will varify the problem Dave. Then tell me what curcuit it is and I'll try and find the diagram and see what's on it.
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mini-fuse 10A position #19. My diagram shows ignition switch upstream and the alternator via idiot light downstream. Fuse pulled I'd see grounding on the upstream side of the block with ignition off.
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I'll check Mitchell tomorrow Dave and see what I can find.
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I need a year and engine size Dave. Is it 2 or 4wd?
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1998 F150 XL extended 4WD 4.6 V8 Triton
blue w ugly old driver :)
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Does it have the slow dimming interior light Dave? I'm looking at the system wiring diagrams rignt now.
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Fuse 19 is for the charging light Dave. Take the fuse out and see if it's hot on both sides. If only on one side then the ignition switch is probably the issue. If I could post the diagrams I would but Mitchell uses it's own PDF reader and you can print it but that's all.
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Fuse 19 is for the charging light Dave. Take the fuse out and see if it's hot on both sides. If only on one side then the ignition switch is probably the issue. If I could post the diagrams I would but Mitchell uses it's own PDF reader and you can print it but that's all.
Alt-PrtSrcn, open up MS paint, Ctrl-V, Ctrl-P = Win!
Sorry, I'm a computer nerd...
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Lost me there Mark. The site has it's own PDF reader and you can't use anything else to open them with. The site blocks any attempt to copy images.
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Lost me there Mark. The site has it's own PDF reader and you can't use anything else to open them with. The site blocks any attempt to copy images.
Pressing ALT and PrtScr keys at the same time does a screen capture of the active window. After that, open MS Paint. Pressing CTRL and V at the same time pastes the screen capture into Pain. Pressing CTRL and P at the same time opens up the print window.
Basically you can print anything you see on your screen. Mitchell is dodgy, but I don't think they can block that.
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I don't have MS paint though.
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Lost me there Mark. The site has it's own PDF reader and you can't use anything else to open them with. The site blocks any attempt to copy images.
Pressing ALT and PrtScr keys at the same time does a screen capture of the active window. After that, open MS Paint. Pressing CTRL and V at the same time pastes the screen capture into Pain. Pressing CTRL and P at the same time opens up the print window.
Basically you can print anything you see on your screen. Mitchell is dodgy, but I don't think they can block that.
And if that fail, camera time. lol
AJ___
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No fancy dimming here, basic truck AM/FM/cassette+ AC
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Is the battery light on when the engine's off Dave? That's what that circuit does so the light should be on if it's getting power.
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Is the battery light on when the engine's off Dave? That's what that circuit does so the light should be on if it's getting power.
Yes, KEY-ON battery indicator illuminated, RUNNING- battery indicator off
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Dunno where I got this one, I think the Haynes matched color codes better but this seems right from a block diagram view
Is this consistent with yours?
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Not even close Dave. Mitchell is much more detailed.
I was talking about with the key off not on.
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Not even close Dave. Mitchell is much more detailed.
I was talking about with the key off not on.
I was wondering that too - Even a dull glow??
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OK, I see what you guys are going.
Not enough current flows in the reverse direction to light the bulb.
Not all the resultant draw happens thru that wire.
It "appears" like enough reverse bias current flows out of the regulator to positively bias something in the regulator cct itself and drawing current.
(told you it was strange)
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Are you sure it's in the reverse direction Dave? Take the fues out and test both sides where the fuse plugs in and see if both sides have power with the key off.
What's the amp draw you're getting?
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My luck isn't so good here lately, but was just wondering how you measured your 2A draw and did you already pull fuses to isolate?
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Just a side note, since I posted I just now got page one of the post. Anybody else have this happen? Plus I hope he gets the truck fixed. We may have fun driving the Buicks but keep the DD's running.
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I do have a work-around. I currently have relay contacts in series with that #19 fuse. Truck turns off, relay drops out, draw goes away.
Pyro:
Yes pulling that fuse makes the draw go away.
The ammeter gets inserted in series with the battery while isolating.You can separate stuff easily around those "master" fuse terminals.
The alternator got changed because disconnecting it also made the draw go away (logical). You can measure the resistance to ground as well as voltage from battery+ and battery- to the wire in question to figure what going on.
Overall Its not the kind of conclusion that leaves you comfortable, like say finding a broken mechanical part.
Was hoping Charlie or Steve or Ed might come up with common failures that might fit the oddball symptoms...
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Are you sure it's in the reverse direction Dave?
Definitely- seemed absurd so multiple checks
Take the fues out and test both sides where the fuse plugs in and see if both sides have power with the key off.
ignition switch side of fuse block, fuse removed:
key on - a nice 12v
key off - 0 volts to ground 12 volts to battery+
What's the amp draw you're getting?
2.5amps
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Change the ignition switch Dave. My best is that the contacts in the switch has gotten funky. Guessing that it's got around 130K or more on the clock now?
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Prolly closer to 170K :)
Maybe more if I drive down and visit supersix in a week :)
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So I got two whole years out of that rebuilt alternator (one year warranty)
Crapped out, they wanted as much for a regulator as the whole thing.
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Idiot battery light stay on tho it's charging now. tried another better alt (bosch),
still the same.
Can anyone confirm that bulb only goes to the "I" terminal of the reg?
If the circuit went open the light should go out. Makes not much sense.
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hopefully this pic helps you out.
(http://i191.photobucket.com/albums/z100/xpander343/fordf150charging_zps3dd59a56.jpg) (http://s191.photobucket.com/user/xpander343/media/fordf150charging_zps3dd59a56.jpg.html)
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Thanks Steve expander! That's how I remember it. Somemore probing is in order...
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Anyone have a name for the alternator's connector series? Presume they aren't metripacks?
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Thanks Steve expander! That's how I remember it. Somemore probing is in order...
Did someone say probing? :player:
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I suppose it IS the rear of the alternator...