A word of caution when tapping into the interior fuse panel.

[sunkid]

Like a few of you, I couldn't wait to install a dash cam the first weekend I had my shiny pon-e in the driveway. Following the excellent tutorial by @MachDoc , I tapped into fuse #4 (see image below, "borrowed" from that post) for a constant-on installation of a Vantrue N4, which worked like a charm.

As the weeks went by (has it really only been 3???), I was loving driving the car, software quirks and all (current trip not resetting reliably, one spurious but scary "powertrain malfunction," a couple of "no chargers in range" warnings, etc.). I figure, eventually, Ford will address these with an update.

However, what bothered me "from the start" was that my key FOB had a very low range and that walk-up unlocking or walk-away locking did not work reliably. I tried both FOBs and replacing the battery of one to no avail. I also tested with just the FOB in my hand and not in my pocket with my wallet (I ended up replacing the strong-magnet-containing wallet anyway even though it didn’t make a difference). My last, desperate thought before talking to the dealer was that maybe the dash cam is blocking the sensors or that the cables that I had stuffed into the mirror housing were somehow causing electromagnetic interference. Sure enough, as soon as I unplugged the camera, my FOB worked well and the car reliably locked and unlocked. I then eliminated one possible cause after another: I removed the camera from the windshield, pulled the cables out of the mirror housing, and unplugged the rear camera, but the only thing that cured the range and reliability issue was unplugging the power from the camera.

So I moved the camera power to the #24 fuse (25 A) and all was fine (that fuse is also constant on).

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[MachDoc]

........

So I moved the camera power to the #24 fuse (25 A) and all was fine (that fuse is also constant on).

Interesting, my keyfob never showed any of those issues. Glad you found a cure.

 

[sunkid]

Interesting, my keyfob never showed any of those issues. Glad you found a cure.

I think the N4 might be drawing quite a bit of power since it is set up for 3 cameras. What still has me a bit puzzled though is that pulling fuse #4 does not disable the FOB sensors.

 

[Logal727]

Sounds like BT interference, happened with my 2019 Honda Odyssey fob whenever it was in the same pocket as my phone.

 

[scoopman]

I switched to a dashcam battery system to power my BlackVue dashcam in parking mode, as I'm afraid of consistently draining my 12V with all of the LVB issues I read from folks. My solution was expensive (and my passenger seat has quite the electronics bay under it with two gigantoid batteries!) but not having to worry about my 12V operating outside of what Ford expects it to do was worth it to me.

If you are drawing from constant power, I think it is prudent to have some protection to cut off power when your 12V reaches a certain low percentage (say 12.3v). Some BlackVue dashcams have this built-in, or there are aftermarket solutions you can wire up to your circuit to have some protection against draining your 12V completely.

 

[sunkid]

Sounds like BT interference, happened with my 2019 Honda Odyssey fob whenever it was in the same pocket as my phone.

I updated my post to mention that I had eliminated that possibility as well.

How do you think switching the fuse might have eliminated BT interference though?

 

[sunkid]

If you are drawing from constant power, I think it is prudent to have some protection to cut off power when your 12V reaches a certain low percentage (say 12.3v).

Valid point! I used the N4’a hardwire kit, which includes a low-voltage cut-off.

 

[Logal727]

I updated my post to mention that I had eliminated that possibility as well.

How do you think switching the fuse might have eliminated BT interference though?

Maybe it was further away from a module? I dunno, I just know that’s like the number one cause of fob issues

 

[ZuleMME]

I never have issues with my fob And have a N4 on fuse 4 exactly as shown. Electrically there is no way this is the problem you experienced unless the electronics connected were specifically creating very carefully designed back EMF. This isn’t the case I’m sure. It’s more likely youve essentially found that “some” wiring connection in that area is loose and intermittently causing trouble when you go digging in that fuse panel. I’d mess with it a bit while leaving it on the new fuse and see if you can cause it to come back. And/or switch back to fuse 4 to see if it returns. This boggles the mind otherwise to suggest what could be the trouble.

 

[DevSecOps]

Ok, so first of all fuse #4 is for the Multi-Function Display, so I don't know that you have correlation between that and the key fob. I think this might just be a case of coincidence or some other type of interference.

Second why would anyone tap into a used fuse spot when there's availability of unused?

If anyone wants to tap into an always on use the unused fuses in spots: 5, 6, 13, 24
If anyone wants to tap into a switched on fuse use the unused fuse in spot: 1-2

All of the micro 2 spots are always on and all of the micro 3 spots are switched.

Don't tap into a used fuse unless you absolutely have to. It increases the draw rating and has the potential to pop-out since taps don't always grab as well as regular fuses. If your tap for a dashcam comes out, boo-hoo, if your fuse for your gearshift module (Fuse 21) comes out then I think you'll have bigger issues.

In the same guide that the OP referenced I posted the correct fuses to use, and that can be found here: https://www.macheforum.com/site/thr...a-dashcam-and-radar-detector.5542/post-262345

 

[sunkid]

It’s more likely youve essentially found that “some” wiring connection in that area is loose and intermittently causing trouble when you go digging in that fuse panel.

I didn't open the fuse panel until I had established that merely disconnecting the power to the camera cured the problem I was seeing. I did this several times in different "configurations" (as originally mounted, cables pulled out of the mirror box, camera dropped to the dash, camera dropped below the dash) and each time the FOB range was low with camera powered and reasonable with camera unplugged.

 

[sunkid]

Ok, so first of all fuse #4 is for the Multi-Function Display, so I don't know that you have correlation between that and the key fob. I think this might just be a case of coincidence or some other type of interference.

I am with you right there. I cannot explain my observations.

Second why would anyone tap into a used fuse spot when there's availability of unused?

If anyone wants to tap into an always on use the unused fuses in spots: 5, 6, 13, 24
If anyone wants to tap into a switched on fuse use the unused fuse in spot: 1-2

All of the micro 2 spots are always on and all of the micro 3 spots are switched.

I need to double-check, but I believe some of these have fuses in place and I have no way of knowing whether any of them are wired to accessories downstream or not.

It increases the draw rating and has the potential to pop-out since taps don't always grab as well as regular fuses.

The first part is true but irrelevant. With all the fuse boxes I have worked with, there is one switched power connection and one always-on connection to the fuse panel itself. Using a proper tap ANYWHERE on the panel only increases the draw on one of those and not on the appliance originally in single occupancy on that fuse spot.

As for taps not being as secure as a single fuse, that is certainly a valid point with low-quality taps. The ones I wouldn't personally use even if I was 100% sure that all that would happen is that the radio stopped working, for example.

 

[DevSecOps]

I need to double-check, but I believe some of these have fuses in place and I have no way of knowing whether any of them are wired to accessories downstream or not.

1	5 A	Not used.
2	5 A	Not used.
3	10 A	Extended power module.
4	10 A	Multi-function display.
5	20 A	Not used.
6	10 A	Not used.
7	30 A	Passenger door module.
8	5 A	Not used.
9	5 A	Auto-dimming exterior mirror.
10	10 A	Extended power module.
11	5 A	Power liftgate. Hands-free liftgate actuation module. Telematics control unit module.
12	5 A	Anti-theft alarm. Keyless keypad switch. Front driver door activation switch. Rear driver door activation switch.
13	15 A	Not used.
14	30 A	Driver door module.
15	15 A	Not used.
16	15 A	Active suspension (GT).
17	15 A	SYNC.
18	7.5 A	Wireless accessory charging module. Driver status monitor. Front passenger door activation switch. Rear passenger door activation switch.
19	7.5 A	Headlamp switch pack. Bluetooth low energy module. Push button start.
20	10 A	Anti-theft alarm horn.
21	7.5 A	Gateway module. Climate control. Gearshift module.
22	7.5 A	Instrument cluster. Steering column control module.
23	20 A	Audio unit.
24	20 A	Not used.
25	30 A CB	Not used.

 

[sunkid]

1

5 A

Not used.

[...]

Great info! What's the source of this?

 

[DevSecOps]

Great info! What's the source of this?

https://fuse-box.info/ford/ford-mustang-mach-e-2021-fuses

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