Parasitic Draw

Parasitic Current Drain Testing With an Ammeter

1. Turn the ignition and all accessories OFF and remove the key from the ignition switch.
2. Disconnect the cable from the negative battery terminal.
3. Follow the manufacturers instructions for the DMM or ammeter being used. This could involve plugging leads into different locations on a DMM and changing the scale to read amperage. On some testers you should start on the 10 Amp scale setting, and after verifying that current drain is less than 2 milliamps, set the scale to 200 milliamps or 20 milliamps.
4. Touch the negative battery cable to the negative battery terminal, and hold them together for 20 seconds. This will allow the modules on the vehicle to wake up.
5. While still holding the cable against the battery, connect the ammeter between the negative cable and the negative battery terminal so that it will be in series. Then remove the cable from the battery. Read the parasitic current drain from the battery.
6. Wait 5 minutes for the modules on the vehicle to go to sleep. The current draw may be greater than 100 milliamps for the first 2-5 minutes, then it should drop to 10-30 milliamps.
7. To find the source of excessive load, remove fuses and modules in a systematic way. When the parasitic current draw is reduced to a normal level, the circuit or circuits protected by that fuse is the source of the current drain. Repair the circuit and perform the parasitic load test again to verify the repair.

Typical Parasitic Loads

Typical parasitic load for this vehicle is 10-30 mA after 5 minutes.