Car has started complaining about a low battery in the morning as of a few days ago (plus it logs a "213601 power management, closed-circuit protection: closed-circuit current violation 80mA" error). I don't recall having changed/added any hardware in this timeframe, so I guess I have to get the multimeter out and see what's going on. There's a lot of aftermarket stuff hanging on the circuits (amp, nav, TV gateway, radar detector, front / rear cameras, etc), so I want to start pulling fuses while running off a multimeter and see where this lands me - but, since the F56 doesn't have door buttons, I'm concerned that the car will stay awake and give me the wrong reading.

What's the best way to make the car sleep with an open trunk / doors? Can I just open everything, put the key far away (it has comfort access) and wait a half hour and expect it "should have" a <80mA draw so I can start testing?

 

Take something like a screwdriver and manually close the latch on the door/truck when its open. That will make the car think the doors are still closed but you'll have access to fuse panels.

 

Yep thanks - discovered that. One thing I failed at was wiring the multimeter in parallel. I thought I had the electrics right, but the battery cut when I pulled the cable. This is what I did:

- Negative pole -> battery clamp -> multimeter black pole.
- Set multimeter to 10A
- Move red wire on multimeter to “fused 10A”
- Red wire -> red battery clamp -> shock tower bolt

I expected this now has a parallel ground via the multimeter. But when I clamped the shock tower, no spark came. Then I unbolted the 13mm main ground … and car power failed. So somehow my parallel wire was not routing any power. Any thoughts on what I did wrong?

 

Not sure if I'm completely understanding how you had it set up, but your ammeter needs to be ran in series with the battery to measure current. You need to disconnect the negative cable off the battery, hook one test lead up to the negative battery post and the other test lead up to the negative battery cable. Now depending on the type of ammeter you have you might have to run a jumper wire in parallel between the negative battery post and cable because the meter might not complete the connection when shut off. You would leave that jumper connected for about an hour so the modules in the car would go to sleep and then remove the jumper to then measure the parasitic draw on the system.

 

So what my friend told me is to make sure I do not break the circuit - ie disconnect the battery and then wire the ammeter and reconnect - because besides the car not liking a loss of power, the system that’s drawing the power might turn off and not exhibit the draw. He was saying I need to first wire it up in parallel so it’s live, and then break the ground from the battery to the body. So that’s what I was trying to do, but it’s almost like my ammeter just simply did not route current.

 

May want to check the fuse in your multimeter to make sure its not blown. Also I like hooking up the meter between the battery post and cable to insure a proper connection and also more late model vehicles have current sensors that won't be reading properly since your bypassing it by grounding to the chassis. I've been doing it that way at work for 15 years and I haven't had any problems tracing down a draw by disconnecting the cable to hook up the meter.

 

So you’re saying I shouldn’t try to build a parallel circuit and flip over to it? Fuse should be OK, I got a new multimeter for this (old one didn’t even have a fuse … it’s like 100 years old lol). It’s just that when I tried this a couple of days ago (and failed), the parasitic draw went away for exactly a day (because the following morning battery was mostly full) - and then it returned from the next day, so been discharging daily. So I’m trying to do this as un-invasively as I can. Would a clamp meter help? I borrowed one but it seems to have only 100 mA range (single decimal) so it doesn’t seem to be reading anything on the positive terminal.

 

Nah I would just try hooking it up inline between the post and the cable, wait with it hooked up for a hour, and then see how many amps it's drawing. Normally anything less than 50mA or .050 amps is considered acceptable. If it reads higher then it's time to start pulling fuses to isolate the draw. Also if you have to start pulling fuses it's good practice to leave them out until you find the one that is the cause so it's a good idea to take a picture of the fuse box so you can easily put them back later.

 

Yeah the bavtool has an error, current draw over 80mA so that seems to be the trigger.

The other thing I’m unsure about (which is why I wanted to be non-invasive) is: if i pull the battery cable and connect the multimeter, will it “wake up” the car and pull >10A and blow the fuse? Or will it still be relatively quiet?

 

I mean everything in the car will be powered once you hook up the meter but it won't pull over 10A unless you did something like try to start it.

 

Enh you’re right, worth a go, the draw is so bad now I have to hook up a backup battery daily to start the car lol.