Racking my brain over battery drain and voltage issues

#1
This is my first post on this site, but I have been reading for awhile.

I'm having an issue that I cant seem to work out on my own.
Over the past couple of weeks, if my Civic sits for more then 24 hours, the voltage would be too low to turn the car over.

First thing I did was disconnect the negative cable and do an amp check. The parasitic draw is about 20 milliamps. No issue there and no need to start pulling fuses yet.
With the negative cable disconnected, I did a voltage check between the negative cable and the negative terminal on the battery and I'm getting 12.16 volts. Not good.

I started at the battery and the positive cable comes off the positive terminal in a Y splice. One side goes into the engine bay and the other side goes to the fuse panel under the hood.

When I disconnect the main feed to the fuse panel under the hood, the voltage drops to zero between the negative cable and negative terminal.
I reconnect the main feed to the panel and started with the main fuse for that panel. Pulled that fuse expecting the voltage to drop and then I can start to process of pulling other fuses one by one, but nothing happened. The voltage stays the same...

For shits and giggles, I just started pulling every fuse under the hood and in the car and not one fuse created any voltage drop over .2 of a volt....

Any ideas?
 
#4
Aftermarket stereo, amp, alarm? Start there, try the main lug on the alt also the comm and brushes can short.

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First thing I did was take isolate the fuse panel inside the car. Isolated the starter motor. When I went to disconnect the alternator and the 12.5 volts between the negative cable and negative terminal dropped .9 volts. The started removing fuses from under the hood and the fuse for the hazard dropped it another .6 volts, the PGM F1 Relay dropped 4.5 volts and the brake light fuse dropped it another .8 volts.
There is still 5.7 volts between the neg terminal and neg cable....
 


civteck

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#5
Thats crazy. Does the car have aftermarket head or tail lights? Led or switchback bulbs? Try disconnecting the main relay under the dash they have known to fail and could be stuck normally closed. Also try disconnecting the ecu, if a or some diodes popped it can draw. Good luck from there ill think some more, let us know what you find.

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