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So when someone tells you that your battery is draining because an open circuit That means that the battery amps are travelling, then dissipating in the form of heat though something, and this can be found with my trusty multimeter set on the ohm's scale?


I've never had this problem but here's how I would proceed if the battery's not draining too quickly. Set your meter to read Amps. Disconnect the battery ground and hook the negative lead of the meter to it. Hook the positive lead of the meter to the negative terminal of the battery. You have now connected the meter in series with the battery. If no current is indicated, the battery may be partially shorted internally.

If the meter indicates current, then you indeed have a closed circuit somewhere in the vehicle's wiring. You probably won't see a big fat zero reading, there's a very small drain for the clock in the radio and the vehicle computer. Before getting any deeper, make sure you've accounted for things like the radio being on or a door ajar and the dome light lit.

Leaving the meter attached as above, go to the fuse box and pull each fuse in succession. Check the meter after you pull each one. What you are doing here is eliminating some possibilities. If a pulled fuse has no effect on the current reading you can eliminate the devices and circuitry served by that fuse as the source of your problem. If pulling a fuse drops the current to zero then you can narrow your search to the wiring and devices on that circuit.

Leave the fuse out which gave a zero current reading. Get the meter and set it up for reading ohms. Connect meter negative to chassis and meter positive to the wire or terminal on the load side of the fuse (the wire which goes to the various devices, ie. loads, to give them power). Note the reading. Trace this wire to all the devices served by the pulled fuse and disconnect each of these in turn as with the fuses.

When you remove the shorted device from the circuit the ohm reading will get really high, an open circuit or infinity is what we're looking for here.

If you've done this and still have the same ohm reading as when you started the problem is in the actual wiring. The offender is lying against the body someplace with insulation rubbed through most likely. This could be a real bugger to find because it may well be hidden.

Things which might help here are pulling on/jiggling the wires in question and opening/closing doors while keeping an eye on the meter.

Is this more useful?
 
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