Parasitic Current Drain Testing With an Ammeter
WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Turn the ignition and all accessories OFF and remove the key from the ignition switch.
- Disconnect the cable from the negative battery terminal.
- Follow the manufacturers instructions for the multimeter or ampmeter being used. This could involve plugging leads into different locations on a multimeter 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.
- Connect the ammeter between the negative cable and the negative battery terminal so that it is in series. Read the parasitic current drain from the battery.
- To find the source of excessive load, start removing fuses and modules in a systematic way. When voltage drops across the tester, the circuit or circuits protected by that fuse is the source of current drain. Also remove the fusible link from the generator to check for a voltage drop. If the voltage drop is greater than 2 volts, replace the generator. Repair the circuit and perform the parasitic load test again to verify the repair.