bshad74

Hi w221 family,

I am back with another question (i have another post about airmatic stuck in sports with no resolution) but this time i would like to hard wire AI Dash Cam. I need help identifying ACC fuse and BAT fuse on either side of the dash that I can use for constant (BAT) power while the car is sleeping and power when the car is either on ACC or start mode. Any help identifying these two fuses will be appreciated [Fuses should be at least 2.5A and between 10-30V]

TIA

fun33

Best Buy used to install dash cams (no matter where they were purchased) for $50. Additional $50 if you have a second rear-facing camera. No idea what their current install fees are.

CQHall

No way in hell I'd have BB do this job...especially not for $50, which means that they expect to be done in like 30 minutes.

bshad74

I called them, first they did say they would hardwire the cam but when they heard it was s550, he said we don't touch that car! Go figure.
There's nothing to it if experts in w221 electronics can identify two fuses inside the cabin fuse boxes.

Shadly1

I don't believe you have any always on fuses inside the cabin. You may have to route a line to the trunk. There is a switched accessory fuse inside the engine compartment on the left side by the firewall. F43 is your cigarette lighter.

bshad74

That's what I am afraid of. How about rear SAM?

Shadly1

F117 is a switched cigarette lighter fuse in the rear. You could tap from that and run another line to the battery. Definitely add a fuse to that line before it leaves the trunk.

Or you could just use the switched source for your dash cam. Low-voltage cutout hardwire kits have a tendency to just kill batteries. You don't want that accessory battery running lower than 12v.

Arrie

I can't quite understand why you need two sources. If you plan to run the camera at all times, i.e. from BAT when car is off and then from ignition switch enabled source when car runs, why don't you just run it from the constant BAT source at all times?

For the constant source I noticed that in the left end of the dash there is constant +12 V coming to the "fuse rail" so your constant source could be there. It probably is the same way in the right end if there are any fuses there.

In my car I have a normal "cigarette lighter" socket in the clove box. I run my dash cam and radar detector from there. Wires go around the clove box door edge to behind the dash end cover and from there up under the bottom of the A-pillar cover. Dash cam wire goes under the A-pillar cover up to the head liner where it turns and runs between windshield and head liner to the dash cam that I have glued to the wind shield behind the rear-view mirror. This location so that the cam does not give a "bad" cop a reason to give a ticket for view obstruction as some of them hate dash cams.

Radar detector wire runs from bottom of the A-pillar cover in the gap between wind shield and the dash all the way to the left corner where my detector is.

I do not run constant power to either device.

bshad74

Well, according to the manufacturer, there are AI capabilities that can be left on when you are away (it does have auto shutoff if it detects a low threshold volt). So for that reason its asking for constant power. ACC is self explanatory. But i like the idea of constant power through fuse box rail (in that case i'd have to put a fuse between the hardwire and the camera. The ACC i'd have to see if i have cigarette adapter in the glovebox (i dont think so though)

Shadly1

Keep in mind that your low threshold is around 11.7v. Every other car wouldn't bat an eye at this. Our cars are "special". Once you get much lower than 11.7v and is detected by a SAM unit, it will throw an undervoltage code. If you've ever had to replace an accessory battery, you'll know just how many there are. It is a big battery though. If you never have to rely on the voltage cutout, you'll be fine. If you run your accessory battery at 11.7v pretty regularly, get used to clearing codes.

As far as the constant power source goes, you're going to have to test for it. I wasn't able to find anything in the front SAM control unit that stayed on after the car went to sleep. You're going to have to close the door, hit the door locks and wait. I think you'll find that just about every fused circuit up front will shut down.

bshad74

completely agree with you on every point.

Arrie

It would be great if the fuse rail shuts down when car goes to sleep. This sleeping happens in about seven minutes with the door open too. In mine the fuse rail stayed powered on the 2013 model I had. I have not checked it on the current 2012 model I have, but I assume it is the same way. I would rather run power to my detector and camera from there than from the clove box.

fun33

An easier solution for uninterrupted power to your dash cam would be to install a dedicated cash cam accessory battery directly into your fuse box. Power your dash cam from the accessory battery. Typically these batteries can power your dash cam in its sleep mode when your car is parked for 1-2 days. If the power level in the accessory battery gets too low, it just turns off the dash cam only and your dedicated vehicle battery is unaffected. Dash cam accessory batteries are usually small and fit under the driver's seat. Your dashcam battery is automatically recharged by your vehicle anytime the vehicle is operating

I have had Thinkware dual channel Dash Cams and accessories batteries installed in all of our vehicles for the past 7 years. This wiring system is very simple and it works perfectly.

bshad74

You are correct, the left (driver) fuse box is continuous power, even after 2 hours when I tested it. I did have to leave the door slughtly open so i can access the fusebox afterntwo hours without waking the car up upon opening the door. I do have empty fuses where I can install a fuse (can i?) and connect continuous power. The question remains about ACC.

bshad74

Never thought of installing a new acc battery. Any details would be appreciated

fun33

Try looking at blackboxmycar.com. They offer most major dash cam makes and models. Their phone tech support is outstanding. They also have numerous instructional videos on their website and on YouTube. Pricing is always very competitive.