Greetings Experts,

I'm experiencing a large current draw that I cannot seem to trace. I believe my car has had a parasitic current draw for a few years now, as the battery would be dead after a week of inactivity and I have to replace the battery every year.

However after heavy rains two weeks ago, the current draw seems to have increased (4.6A on the multimeter). I tried removing the small form-factor fuses, both in the engine compartment (as outlined in red in the picture) and the passenger comportment, but so far, no dice.

Once I jump start the car, it seem to run normally and recharges the battery,


if only for a bit. I am therefore curious to see if anyone has suggestions how to further troubleshoot the cause of the draw.

 

How do you have those leads hooked up? If I am not mistaken, you have to use the 10A jack on a Fluke Series 77 DMM to measure current draw. And you have to have the meter hooked up in series between a disconnected battery cable and its respective battery post. If you hook up the meter with the lead plugged into the 10A socket and put the leads across the battery, you will instantaneously blow the fuse inside the meter.

Also, a constant 4.5 amp draw would probably discharge the battery in something like 12 hours to the point that it would be unable to start the car.

Measuring parasitic draw can be tricky. I believe this is what you need to do.
Disconnect the leads from the vehicle or battery.
Leave the range switch at DC Amps (where it is in the pic)
Move the red lead to the 10A jack on the meter
With the vehicle turned off, doors closed, nothing plugged into lighter sockets etc,
Disconnect the negative battery cable.
Connect the end of the meter's black lead to the negative battery terminal and the meter's red lead to the negative battery cable.
Now if for any reason, the vehicle is drawing more than 10 amps, the fuse in the meter will blow. That's why it's important not to open a door or touch the keyfob remote while doing this.
The meter should display the actual current draw but, because we just re-booted every system in the car by disconnecting the battery, it may take 30 minutes or so for the systems to go into sleep mode when the current draw may be significantly less that the initial reading.

 

You need to check the power relays as well.

 

Did you hook up your dvm to the negative battery cables and pull the fuse's one at a time ? That's the way i have always done it . Have you checked the BCM ?

 

That's something I had not tried (always a problem removing these things). Thanks will try it out and report back

 

I did half my tests with with the ampmeter on the positive side before finally thinking better of it and switching to the negative side. The meter didn't burn so I'm assuming the tests are still valid.
However, I did not try to remove the BCM. Will try it out and report back. Thanks!

 

Good catch, you're absolutely right, I didn't even realize I had forgotten to switch the leads! I guess I'm repeating the experiment tomorrow and this time, including the relays and the BCM. Thank!!!

 

So as a quick update, after some investigation, if I disconnect 3 fuses in the engine compartment:
-AT Eng
-ABS
-Room

The parasitic draw drop by one amp (from 1.16A to 0.18A).

Would this point to a specific problem or three separate problems that are overlapping? The only non-stock item on the car is a remote starter.

Thanks

 

This is usually the main issue on vehicles. If you can, try disconnecting it temporarily and get some measurements on if any power is still being drawn.