Testing a Motorcycle System for Current Drain

Make sure your digital multimeter is set to DC AMPs which is “A” and “-” for VDC. Connect the black (negative) wire to the “com” (common ground) input and plug the red (positive) wire into the lowest amp input. If the current drawn is more than your multimeter low setting, move to the high setting.

Switch everything off on the bike such as the lights and radio. Turn the motorcycle off.

Disconnect the negative battery lead. Connect the negative multimeter Lead to the battery negative terminal. Make sure the negative lead you removed from the battery does not touch anything grounded, like the bike frame. Connect the positive lead from the multimeter to the negative lead you removed from the battery. You should now see current drain measured in amps.

The acceptable amount of off-key drain depends on the motorcycle’s onboard electronics and accessories. A factory service manual should list how much is permitted.

Start to unplug the fuses on your motorcycle. If the reading on the multimeter does not change, plug the fuse back in and move to the next one. If the current reading goes to zero or drops significantly on any, you have found what is creating the parasitic draw.

Look at your user manual to find out what is powered by the fuse that is causing the draw. The repair will be determined by what the issue is, but at least you now know what it is.

If a parasitic drain is identified, then leave the battery disconnected until the issue is fixed.

See our Multimeters & Battery Testers