W205 C63s 12v Switched Fuse Help

[Aibonator]

Trying to fit a dashcam to the new motor. Want to wire it to the passenger fuse panel 301-341. Looked at the fuse map in the fuse box and there is a fuse for the Panoramic Roof. This must be switched 12v because the sunroof won't open if the egnition is off. But there is no fuse in the slot?

1. Am I missing something in the way I'm reading it?
2. Does anyone know if there is a 12v switched live in that footwell fuse box. I've put the meter on all of the fuses and I'm sure they are all constant feeds.

Alternative was to try the drivers side dashboard but I couldn't get the cover off. Felt like either it, or my fingers would break in the process.

Cam is a BlackVue 650. Currently wired to the constant feed. But this cam doesn't have an on/off button, and so is always on, so having to pull the power every night so it doesn't kill the battery.

Thanks in advance.

 

[chrisdean]

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Try something like this above and use an "add a fuse" to tap into the fusebox so you're not cutting any wiring.

 

[Aibonator]

Thanks for the reply. The cam came with a Power Magic Pro which does exactly what you describe but it needs a 12v constant feed and a switched feed, hence my failing quest to find a switched feed in this particular fuse box. I have the fuse taps as well to avoid splicing the wires.

 

[Deleted member 113659]

Just a shot in the dark but isn't the usual method to use the cigarette lights fuse?

 

[Aibonator]

Problem sorted. Looks like all the fuses in the footwell are constant. Wired it to the boot fuse box. Much easier than I thought. As stated above the cig lighter fuse and the seat heater fuses are both switched. Job done.

 

[richard]

Aibonator, just to explain your original point about pano roof, all the ECU's in the car have permanent power (some of which, on newer cars, do switch off some hours after ignition off or if battery is getting low).

The ECU's know whether ignition is on or off (and thus how to behave) because they are all networked together using a protocol/network called CAN.

The thing to remember about this, if that if you are testing for a permanent feed (for feeding a power magic pro for instance) you need to be sure the one you think is live with ignition off may well turn off after a few hours or if the car battery gets low.

Of course knowing which circuits do actually turn off could negate the need for a power magic pro, but it is much more configurable.

Cheers

Richard

(nb, a power magic pro keeps power to a witness camera on for a time after you leave the car, but also detects battery getting low and turns it off so you don't run down the car's battery)

 

[KrucaBomba]

Problem sorted. Looks like all the fuses in the footwell are constant. Wired it to the boot fuse box. Much easier than I thought. As stated above the cig lighter fuse and the seat heater fuses are both switched. Job done.

Hi Aibonator! I am trying to do the same thing - fixing Mivue Smart Box to power dash camera. Smart Box requires connection of one wire to fuse from which power is always supplied and one to fuse from which power is not supplied when the car is turned off. Which two fuses you've finally chosen? Does it work fine after instalation?

Thanks in advance for your help!

 

[richard]

Be slightly careful here, modern Mercs from W176 onward have lots of seemingly permanent power circuits that power down after 6 hours of ignition off (or if the battery voltage drops below a certain point). The more modern, the more turns off.

So if you're wiring a witness camera that you may want to work some hours after the vehicle has been locked you need to find the correct circuit.

Cheers

Richard

 

[KrucaBomba]

Sorry - I read Aibonator's post once more and I can see that you are using only switched fuse and I need both types. So rephrasing my question: I can take cigarette lighter as switched fuse and which one can I take for constant feed? I can use fuse box from the trunk or one from passenger's foot area - I do not know how to access fuse box in the dashboard (I have left hand drive car). Any suggestions?

Thanks!

 

[KrucaBomba]

Be slightly careful here, modern Mercs from W176 onward have lots of seemingly permanent power circuits that power down after 6 hours of ignition off (or if the battery voltage drops below a certain point). The more modern, the more turns off.

So if you're wiring a witness camera that you may want to work some hours after the vehicle has been locked you need to find the correct circuit.

Cheers

Richard

There is aniti-theft alarm fuse in the box in the dashboard - I guess this one is always feeded. However I do not know how to access this box :-(.

If the power is off due to battery voltage drop down - it's OK - in fact this is what Smart Box will also do.