Help Fuse Box Installation

FedeDC

New Member
Joined
Sep 19, 2018
Messages
2
Reaction score
0
Country
United States
Hello guys,
I'm installing a Smart Rearview mirror not a dash cam but the wiring is quite similar.
I need some help please. I saw similar posts about this in this forum but I need further clarifications I never did anything like this before.

I'm installing a Smart Rearview Mirror that gets the power directly from the Fuse Box. I have an Mk2 Audi TT 2008 2.0L Coupe.
I ran all cables and already installed the smart mirror. I need just to connect it to the fuse box.

I got 3 cables:

1x Red cable with ACC label (can I use an empty available space in the fuse box?)
1x Yellow Cable with BAT label (got also a "3" fuse on the cable itself) (can I use an empty available space in the fusebox?)
1x Black with GND label (where should I attach the ground? can I just connect the ground to one of the screws on the right of the fuse box?) see red mark

Also for the red and yellow cable how do I know which is the correct side to insert them in the fuse box? They are capable to connect directly to the fuse box. Should I create a "Add a Circuit Fuse Tap "Piggy for each cable or directly connect them to an empty fuse space?)

Can somebody please guide me where to connect these cables? in which fuse spot they should land?
I bought already a Multimeter in case I should do some testing but I never used one before could you please guide me how to use it... :}

This is what I got:
 

Attachments

  • IMG_0432.JPG
    IMG_0432.JPG
    253.6 KB · Views: 12
  • IMG_1064.JPG
    IMG_1064.JPG
    391.6 KB · Views: 12
  • IMG_2303.JPG
    IMG_2303.JPG
    307.8 KB · Views: 11
  • IMG_5788.JPG
    IMG_5788.JPG
    320 KB · Views: 12
  • IMG_6462.JPG
    IMG_6462.JPG
    198.3 KB · Views: 13
  • IMG_7040.JPG
    IMG_7040.JPG
    353.5 KB · Views: 10
  • IMG_7301.JPG
    IMG_7301.JPG
    194.3 KB · Views: 10
  • IMG_8608.JPG
    IMG_8608.JPG
    259.7 KB · Views: 10
  • IMG_8954.JPG
    IMG_8954.JPG
    313.1 KB · Views: 12
I'd recommend getting some add a fuse for a cleaner and more solid install, shouldn't be too expensive.
You could use empty fuses, but it's a little more work finding out which are constant or switched.

So ground your multimeter on some metal, with your car off then start touching the tiny bit of metal that shows through the top of the fuses.

Since your car is off, only constant fuses should light up. You need to connect your yellow wire (BAT) to a constant fuse.

For the Red (ACC) wire, you need to find a switched fuse.
So since you were already looking for the constant fuse before, you should have noticed some fuses that don't light up the multimeter.
Turn your car on and recheck those fuses that wouldn't light up - they should now that your car is on.
After you feel like you found one, turn your car off and double check if the multimeter lights up again. (If they still light up the multimeter while the car is off, your car might have a switched fuse delay - where the fuses still have power for usually up to 30 minutes, your car might not have these)


As for the black (GND) wire, under a bolt that is attached to the metal frame of your vehicle is best. So the bolt you circled in red, isn't ideal since it's on plastic. Try to find one that has the bolt on metal.

If you look on youtube "how to hardwire dashcam", you'll likely find a bunch of walkthrough results showing more about the multimeter and what not.


If you're still unsure, it might be worth asking your local dealership for more info on the fuses, you're manual will have more details too.

Hope this gives you a better idea.
 
Thank you for the infos!

So if I plug in the smart rearview mirror in the empty fuses with the cables provided without add a fuse is it a bad idea counting that the yellow cable comes with a fuse already installed on it?

If I go with the add a fuse way should I add them to both cables even the BAT that got already one pre-installed?

For the multimeter in order to test the fuses to see if they are constant or not should I put it AC Power 20 correct? what's I'm looking for in the results?

Does it matter If I plug in the modified cables in the small fuses at the top of my fuse box (5 or 10 amp) or if I go in the bigger fuses spots at the bottom (5-10-15-20-30-40)

I was looking at the Fuse Box Diagram and the Cigarette Lighter Spot would be great for ACC but it is a bigger 20 amp fuse. If I create an add-a-fuse with bigger fuses and I add back the original 20 amp fuse + a new 20amp fuse should work or do I risk to fry something?

As a rule of thumb do I have always to match the fuse that I see on the fusebox spot with same fuse amperage on add-a-fuse cable for the rearview mirror?

Thank you!
 
Anything ran from any power source needs to be fused. "Add-a-fuse" is the simplest easiest way, but in-line fusing will work too. Most of the newer cars have at least a partially computer controlled power scheme which can affect the behavior of different circuits, so always do a 'real world test' after wiring to be sure it's working as you intended. Some cars have a fully computer controlled power scheme which may make it nearly impossible to find an "ACC" circuit which behaves as you need it to. All you can do with those is try different circuits or contact your dealer (or car audio shop) for assistance.

Phil
 
  • Like
Reactions: Mtz
Thank you for the infos!

So if I plug in the smart rearview mirror in the empty fuses with the cables provided without add a fuse is it a bad idea counting that the yellow cable comes with a fuse already installed on it?

If I go with the add a fuse way should I add them to both cables even the BAT that got already one pre-installed?

For the multimeter in order to test the fuses to see if they are constant or not should I put it AC Power 20 correct? what's I'm looking for in the results?

Does it matter If I plug in the modified cables in the small fuses at the top of my fuse box (5 or 10 amp) or if I go in the bigger fuses spots at the bottom (5-10-15-20-30-40)

I was looking at the Fuse Box Diagram and the Cigarette Lighter Spot would be great for ACC but it is a bigger 20 amp fuse. If I create an add-a-fuse with bigger fuses and I add back the original 20 amp fuse + a new 20amp fuse should work or do I risk to fry something?

As a rule of thumb do I have always to match the fuse that I see on the fusebox spot with same fuse amperage on add-a-fuse cable for the rearview mirror?

Thank you!


You want to the V (DC) 20 setting, which is the 5th dot looking clockwise from the top, or exactly at 3 o'clock, or 90 degrees right, etc... The V is for Voltage, and the solid + dashed line next to it indicate it's for Direct Current (DC) measurements. The V with the ~ line indicates Alternating Current (AC), which you don't want to use in this case. Just so you know, the number (20) indicates the resolution. 20 should mean you can measure up to 20V but might also mean it measures 2 digits to up to 99V. Anyway V DC 20 is what you want to measure with.

Personally I would use a piggyback (add-a-circuit) fuse to supply your red wire. As @SawMaster said, you should fuse everything. Why it didn't come with an in-line fuse like the yellow cable I don't know.

Your idea to tap the cigarette lighter fuse is good, I would do that too. The way a piggyback fuse works it that it leaves the original circuit in place and as such the 20A fuse in there currently should remain. In the second slot for your new circuit you should add another 3A fuse. If your dashcam is faulty and pulls more than 3A then the 3A fuse will break. If the cigarette lighter draws 19A and your dashcam another 1A then your 3A fuse will not break, but the 20A fuse will. That is how it should work.

Anyway always check the instructions with the piggyback fuse you buy, but most of them are like this:
fuse5.jpg

The original fuse should be your 20A one, and the new one should be 3A. Just make sure you get the right size piggyback fuse, as it looks like your 20A fuses are possibly Maxi fuses, and those are not available in 3A versions. So you might want to consider tapping a different circuit (with mini fuses), or use a larger fuse for your dashcam.

For the yellow wire, I would find an empty slot that is live while the car is off and fit it directly - no need for piggyback.
 
Back
Top