another dreaded electrical problem.

1135 Views 10 Replies 4 Participants Last post by systronic, Oct 4, 2005

systronic

Discussion Starter · Sep 28, 2005

in my 88 lx hatch the battery likes to drain over night.
i checked for continuity on all my fuses and found that fuses number 4 and number 8 are both drawing power while the car is off. i also found that when i put the fuse back into plug number 8, it sparks, which makes me think there is some type of short or ground out somewhere in that system. am i correct?
fuse number 8 circuits the key warning, radio, fuel door, and interior courtesy lights. i want to say that its possibly the fuel door, because it does not work, which could mean its grounding out somewhere?

i pulled fuse number 8 and left it out for the night. if it starts in the morning, its on that circuit.

if anyone has any suggestions, feel free to leave me one.

much appreciated
-sys.

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systronic

Discussion Starter · #2 · Sep 28, 2005

well, just an update, i left the fuse out all night, and still no power by morning.
i checked the alternator, and its charging at 14.5 amps, which is perfect. i guess ill run and get the battery tested somewhere just to be sure, but its like brand new...

anyone has an advice for electrical probs let me know

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tom.moss1949

· #3 · Sep 28, 2005

Disconnect the alternator over night and see if it still does it. There is a "blocking diode" in the alternator that can short out and drain the battery when the alternator is not making current.

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GhostDog 5.0

· #4 · Sep 28, 2005

My ignition switch did a similiar thing when it was toast.

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tom.moss1949

· #5 · Sep 28, 2005

That could do it too........

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systronic

Discussion Starter · #6 · Sep 28, 2005

alright, so ill try the alternator

about the ignition switch
to test, should i remove the switch entirely from the column? or can i just disconnect the wiring harness from it

thanks for the help fellas. its my first stang so im really pumped. i have a disconnect switch hooked up to the battery that gets the job done for now, but id like to solve the problem by next spring.

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Stangboy5666

· #7 · Sep 28, 2005

same exact thing happened to me when my alt failed. I couldnt tell from anything else that that diode had gone bad either, but it had. Then it got worse and worse, in the end i bought a 140 amp alt from PA performance, and its an awesome alternator. Good Luck

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tom.moss1949

· #8 · Sep 28, 2005

Stangboy5666 said:
same exact thing happened to me when my alt failed. I couldnt tell from anything else that that diode had gone bad either, but it had.

Yep, the alternator still puts out voltage/current just fine, it just drains the battery when the engine is off - that's when the diode fails shorted. If it fails open, the path for current is open and the alternator won't charge.

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systronic

Discussion Starter · #9 · Oct 3, 2005 (Edited)

thanks for the help fellas, it was the alternator.
i pulled the plugs on it, and then the next morning, hooked it back up, and she fired right up no problems. im probably going to pick up a 140 amp, maybe a 160 amp. any suggestions on an alternator, leave em please.

thanks again! :happyhapp

edit/update:
well, i went ahead and took the initiative and bought a 160 amp motorcraft 3g alt. comes with instructions for boltin onto my 88 and all necessary connectors. if you guys have any precautions for me for installing this alternator, or any other mods i should do before i do install it, please feel free to leave em.

thanks!

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tom.moss1949

· #10 · Oct 4, 2005

Make sure you disconnect the old black/orange wire to the battery and replace it with a cagble rated for 160amps - a #2 wire.

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systronic

Discussion Starter · #11 · Oct 4, 2005

roger that. it should be here by the end of the week. for now, check out my latest thread on my amazing experience installing white gauge face overlays.... i know some guys think its queer, but they are rather sporty in my opinion

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