How To Perform a Parasitic Draw Test

How To Perform a Parasitic Draw Test? Vehicles come with lots and lots of complicated settings due to the fact they have numerous features supported by various connections and power sources.

The power sources could be the fuel you are using and the car battery. As its clear to everyone the fuel will be running the car while electric works are handled by the car battery, and a car with any of these absent or faulty cannot work at all or may cause issues right at the time when you start the car.

Here we are going to discuss one of the issues that most of us might have to face any time when we stop caring your or maybe we just start noticing something strange in our car that it doesn’t go to sleep when it has been set to sleep, meaning that it still is in a condition when there is an electric draw even when your car is not using any electronic component.

The result comes in the form of a condition when you try to start your car and start just saying, nay…

So, what you have to do is to try turning on your car through ignition key and if it doesn’t pick up the ignition, what you will think is, Yes! The battery is dead, right?

So, lets check out the battery and see if the charge is low. Let your car battery to charge overnight and let retry in the morning, put in the ignition key and try starting it over, now the awful situation would be the car still not picking up the ignition.

Now what? There could be a condition when the car may have a parasitic draw of electrical charge due to some faults in the circuit itself. That means when your car is set to sleep, it would sleep rather an electric discharge keeps flowing even when you are not using it, causing the battery to lose each and every bit of the charge.

How to test if there is a parasitic draw in your car?

Things you’ll need

  • A multimeter with amp scale up to 10 amps
  • Clamps with wires
  • Fuse picking tool

Follow the following steps

Step 1

Check your battery, let it charge till its fully charged and then start your test. You should check that your car is not using the charge at any point.

Turn off all the lights, take out your key, close all boxes and doors, turn off any component within the car, interior lights, and the doors should be closed before you start testing where the electric discharge is located.

Step 2

Connect your multimeter to your car. You just have to set it o amp value, so connect it via amp scale rather than mili Amps. As you have to start with a higher value. Set the dial to 10 Amps to check the charge disposal.

Connect the multimeter to the battery through negative terminal, though any of it is okay, but the negative terminal is preferable in order to avoid any short circuit in case of touching the ground, if you are attaching it in series with the positive terminal.

Step 3

Attach the leads to the negative terminal and see the electrical draw. You will have to attach one lead with the cable you have removed from the terminal and the other lead to the terminal.

The reading you can see on the multimeter is the amount of parasitic draw your car is facing. And remember, it should not be more than 50ma. But if it is higher, it surely is damaging.

Step 4

Start to explore where the amp draw is, pick your leads and attach to the point where the fuse box are attached. If you see the same reading on your multimeter then you must know you’ll have to check all fuses, including the ones under the box, and the ones located under the dashboard.

Put out all of them one by and keep looking on the multimeter. When you put out the faulty fuse, you will see a significant fall in the value shown by multimeter.

Step 5

Check on the faulty fuse and figure out the circuit using the circuit diagram of that unit. This will let you know where the problem lies and you can fix the wires or any connection issues that are there.


Disable your door switches by keeping it suppressed to avoid extra electric discharge and pressure on multimeter.