"Electrical System Drain. Service Required." DIY Fixes?

[lister coggs]

@lister coggs did you manage to get your drain issue sorted? I'm curious what was causing your problem.

Nothing yet! Ford had my vehicle for a couple of days last week. At first, they said the terminal bolts were loose again (I'm pretty sure they weren't), then they had it for another day and said they were having trouble with it, but were able to reduce the draw from 6 amps to 1 amp. I had to take the vehicle back for the weekend, and I'm giving it to them again tomorrow.

I put the monitor back on last night. The symptoms are the same as before I gave it to them (SOC stays at 100% when the HV battery is plugged in, drops immediately when not connected).

I don't know how much it will cost to have Ford investigate this issue. I was under the impression they charge for time spent diagnosing, which could cost a fortune since they don't seem to be familiar with the issue. I found this video on checking parasitic draw and might give it a whirl later today:


I have a feeling that it might be related to the motion sensor refusing to turn off as I hear that is a common culprit.

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[Adventureboy]

I think there are multiple motion sensors all connected to the BCM so I expect it isn't a simple thing to track. Keep us in the loop - I'd like to see what they track it to.

 

[lister coggs]

The monitor only estimates SOC based on the voltage trends so it can be off a bit since it doesn't directly track the current in/out of the battery like a BMS, but it is close enough to show the trends pretty clearly.

The voltage chart doesn't show the SOC trends as well, but it tells the same story. Something isn't shutting down properly in the truck. I'm curious how many cycles it will charge/discharge before going into sleep mode. On my 2023, it would only do it once initially. Ford updated that charge profile sometime in 2024, I think.

Another thing to watch. When the truck goes into sleep mode, does the drain still happen?

Any chance you have or know someone with an infrared camera? If you point it at the fuse box and snap an infrared photo about an hour after shutting down, without a keyfob or PAAK around it may tell you which fuse is carrying the current. The problem is you need to sit in the truck and wait for 45 minutes to get the picture since opening a door will light up the modules.

If you're curious, I tried an infrared camera on the passenger fuse panel and this is what it showed.

I tried taking the top fuses out and the parasitic draw remained, though, so I gave up on that technique.

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[mr.Magoo]

If you're draining your 12V battery in 1.5 hours it's pulling around 15A which is a heck of a lot more than "parasitic" drain and as such it should be fairly easy to track down.

Personally I'd start off with getting a cheap clamp meter, stick it on both positive and negative leads to verify that it's more or less the same, then leave it on either one and start pulling fuses until it redicuces / goes away (it'll be faster if you have someone keep an eye on the meter while you pull fuses), once you know which fuse you now know which direction to look, rather than fumbling more or less in the dark.

Just keep in mind that the truck will wake up when you open the doors and it'll take 10-15min to go back to "sleep", so you'll have to give it that time. It would buy you some more time if you were able to hook up a charger / powersupply.

 

[bmwhitetx]

Personally I'd start off with getting a cheap clamp meter, stick it on both positive and negative leads to verify that it's more or less the same, then leave it on either one and start pulling fuses until it redicuces / goes away (it'll be faster if you have someone keep an eye on the meter while you pull fuses), once you know which fuse you now know which direction to look, rather than fumbling more or less in the dark.

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:

 

[lister coggs]

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:

Great call out. It looks like the cheap one at Princess Auto (Canadian Harbor Freight) will do AC/DC. https://www.princessauto.com/en/mini-digital-clamp-meter/product/PA0008344707

Will give that a go later today.

 

[bmwhitetx]

Great call out. It looks like the cheap one at Princess Auto (Canadian Harbor Freight) will do AC/DC. https://www.princessauto.com/en/mini-digital-clamp-meter/product/PA0008344707

Will give that a go later today.

It looks like that one will only do AC amps, not DC. It has the sine wave symbol next to the 20A, 200A, and 400A scale. That indicates AC only.

If it did DC there would be a horizontal line with three dashes below it. Note for the Volts scale there is a setting for 300V AC (sine wave) and 300V DC (line with dashes).

 

[lister coggs]

It looks like that one will only do AC amps, not DC. It has the sine wave symbol next to the 20A, 200A, and 400A scale. That indicates AC only.

If it did DC there would be a horizontal line with three dashes below it. Note for V=Volts there is a setting for 300V AC (sine wave) and 300V DC (line with dashes).

Great call (again).

From the description: "Measures AC/DC voltage, AC current".

I'll probably just set up my regular multimeter for the testing. Confirmed it can measure DC current.

 

[bmwhitetx]

Great call (again).

From the description: "Measures AC/DC voltage, AC current".

I'll probably just set up my regular multimeter for the testing. Confirmed it can measure DC current.

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.

 

[bmwhitetx]

This is the cheapest DC Clamp meter I can see on Amazon. Note for the Amp scale it has both the sine wave and the line - indicating AC or DC.

To specify AC or DC then , you press the Z/F button until DC shows in the display.

 

[mr.Magoo]

I'll probably just set up my regular multimeter for the testing. Confirmed it can measure DC current.

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.

 

[lister coggs]

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.

 

[bmwhitetx]

I'm going to pick up a Klein clamp meter.

3 of theirs that also do DC amps.

 

[Zprime29]

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:

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?? Hey Santa!

 

[lister coggs]

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.

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