Parasitic drain - can’t find problem

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mflynn

mflynn

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Virtually overnight about 3 weeks ago, with no prior warning, car wouldn’t start. Battery dead. Short story - I have replaced battery and tightened alternator belt. New battery drains after a few hours. Checked amp draw - about 4.4 amps (?) on multimeter so something is going on. But I pulled all fuses and there was no decrease on the draw, so I haven’t been able to pinpoint where the short is. Any ideas, similar experiences? This is a summertime daily driver which has had zero problems since putting it on the road about two years ago. Fires up every time - until 3 weeks ago. For now, I am disconnecting the negative/ground battery cable every time I park it, and it starts up every time.
 
Alternator and or regulator. You’ve already isolated downstream of fuses so check your draw and start disconnecting stuff to see when it quits. Diode/rectifier can have a diode getting weak and allow current flow.
 
Dubob said:
Alternator and or regulator. You’ve already isolated downstream of fuses so check your draw and start disconnecting stuff to see when it quits. Diode/rectifier can have a diode getting weak and allow current flow.
Click to expand...
So just disconnect the alternator? The alternator was purchased new and installed as part of my rebuild. Could it go bad this quick (about 20K miles)?
 
Yes disconnect put meter in line as you have been and see if draw disappears. Regulator can also cause a draw. Don’t know what your set up is but the replacement parts are not always reliable.
 
I had a similar problem & it was a bad battery- oh it was intermittent too.
 
Get one of these!
s-l1600.jpg
 
Remove positive battery terminal lead, take a standard 12v test light, clip one end to the battery, put the probe end on to the cable end. the larger the draw, the brighter the test light gets. Start removing fuses, cable, Alternator, starter relay, any thing that takes power. when light goes out, no more draw.
 
An IR-meter should be able to pick up any warm wiring. 4.4 amps is a lot and should really be measurable.

I would want to say your ignition switch isn't disconnecting everything anymore perhaps, or it constantly goes to Acc-mode now.

Does the engine 'turn off' normally?
Thinking if the ignition system or the coil stays under power, it could draw a similar amount of power, but then you wouldn't be able to turn off the engine very easliy. This situation would also most likely burnout the coil or something electrical in the ignition system first.
 
4.4 amps could be as simple as two incandescent bulbs on. Have you checked it in the dark. The glove box and ingnition switch lamp both on could draw that. Likely not them but look harder.
 
What are we working on here? Does it have a "key in" light?

Good ideas above, disconnect the main alternator wire, the nut/ stud

Also try disconnecting the ignition switch

That is a "fair" amount of draw.....should not be that difficult to find
 
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