Yeah, you'll have to break the circuit, i.e., remove the negative terminal from the battery and put your ammeter leads inline. Make sure you are selecting the right banana jack on the meter.The amps scales route the high current through a shunt and measure the voltage drop across it.
That would be an option for lower currents, but if yours is pulling upwards of 15A it's more than most multimeters can handle (so make sure you check that) and best case it's fused and you'll blow the fuse, worst case and it isn't and you'll fry your meter.
Yep, pretty sure you just saved my multimeter. Lol. It's rated for 10 amp maximum. I'm going to pick up a Klein clamp meter.
Wish I had known this when I bought my meter (an Ames from Harbor Freight). I needed it to measure the capacitance on my A/C's capacitor this past summer. I'd have splurged a bit more for one that did DC current had I known. I guess one can never have too many multimeters??This is an excellent idea. I would just note that most cheap clamp-on meters you find at Lowes or Harbor Freight will only do AC current (much easier to do). You will need a clamp-on that does DC current. Those are usually more expensive.
Look at the specs, they will all say AC/DC voltage, but will likely only says AC amps. You need one that says AC/DC amps. The symbols on the meter tell you which:
Hey Santa!
I have a BTMETER BT-570 (amazon) clamp meter with bluetooth which can measure DC current and can log Amps over time. It's showing -1.8A on the + battery cable when charging. 8.4A when not charging (frunk light is on, probably other loads as well). I plan on logging the 12v battery power when I get a chance... I recently had mine in the dealer for factory recall issue and asked them to look into a "powertrain malfunction" error I received earlier. They said they didn't see any issues and just reset the DTC codes. Luckily they didn't charge me anything but I'm not too confident they'll be helpful in the future.Update: I tested every breaker in both the frunk and the passenger-side panel. The only notable change was when I removed fuse 210 in the frunk panel, the current draw dropped from a steady 8 amps to 4 amps.
Fuse 210 is referenced as the Body control model. I dropped the vehicle back at the dealership this morning. They said I was only $200 CAD in the hole for diagnostic fees based on their hourly rate, but hinted that a considerable repair bill was coming since it will most likely require replacing the BCM.
This kind of sucks. I'm used to working on simpler vehicles, and it seems like I'm pretty much at the dealership's mercy here, since they can basically say it's anything. On one hand I wouldn't be surprised if this is fixed with a software update, on the other hand I'm looking at a 2-3K repair bill for a new BCM.
I'm just out of B2B warranty, it probably makes sense to just tolerate the parasitic drain when off shore power and potentially deactivate the battery whenever I leave the vehicle. Something I didn't want to do with a fairly new truck.
To make matters worse, I noticed a panel in the frunk was completely cracked. Something I don't recall doing, and have relatively recent photos with it being uncracked. I mentioned the damage to the dealership gently, and since I had already had it for the weekend before noticing, they said I could have cracked it myself.
Will update when I hear back from the dealership.
Mine was pulling about 8 amps when not charging. It took awhile to trace, but the dealer said they've diagnosed it to the telematics control module and have ordered a replacement.
