Parasitic drain... UGH

[Stradbrother]

Well... I'm stuck, guys.

Here's a rundown...

I have a 1991 Ford Festiva. Runs and drives awesome. But every few months, the battery dies.

-Multiple batteries have been tried, all drain.
-New alternator
-New battery terminals and cables
-New timing belt

The alternator does charge the battery. This morning the car's electronics were running slow and the horn was quiet, so I knew the battery was dying again. Once I got to where I was going I locked up the car and let it idle (turning off the car would have me trapped), after about 25 minutes in the store I came back out to the car still idling well, and the electronics were working normal like the car just got a boost of energy from sitting there.

There is a drain somewhere and I cannot figure it out. The battery runs dry every few months almost predictably, but the alternator is working...

I'm just lost, guys. Anyone have any ideas?

[bravekozak]

What is the amp draw with the car totally shut off?
No engine running, no lights, no buzzers, doors shut.
Clean all your grounds (where the black wires bolt).
Remove inspect, clean and replace both door switches.
Bypass the dimmer switch on the dash and report back.

I really hope its not your ECU turning on sporadically.

Your best friend.

[David88]

I bought a 93 Mazda protege a few years ago that had the same issue. Took me a while but ended to slowly tracking it down with a volt meter. Someone probably punched the horn button and it stuck on, so they unplugged the horn wire at the horn. That left the horn relay energized causing the draw. Unplugged the relay and all was well.

[WmWatt]

Could you hook up an ammeter to the battery then unplug fuses one at a time and see if the current drops? That would isolate the drain somewhat?

[ryanprins13]

Does the charge light come on when your electronics start running slow and the horn gets quiet? Does it come on when the car is off and the key is on?

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[ryanprins13]

Because it comes back on randomly it could be a loose connection somewhere in the wires that signal the alternator to charge and how much to put out. Here is a photo of the diagram. If the fuseable link is corroded or has a bad connection it could intermittantly not charge. Same as where the wire goes into your instrument cluster and by the bulb. That connection needs to be complete i believe. Plug needs to be tight on the alt obviously. Is the clip that holds it on there still good? My one festiva sometimes will stop charging and the light comes on while im driving. I have to pull over and wiggle wires in the engine bay till it charges again. Then im good for another 8 months or year. I think the wires are perhaps broken inside the insulation or something on mine.


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