Amp power cable through firewall?

Dec 31, 2020
Has anyone here fitted an amp in a mk3 leon? I'm really struggling to find a way through the firewall on either side of my 2019 FR. My main problem is not being able to see behind the glove box. It's the uk version so the fuse box is directly behind the glove box which appears to be blocking my view.

Has anyone else successfully done this and if so how did you get the cable through? Any pics would be great. Cheers


Active Member
Jun 1, 2018
I've found it best, on modern cars, to use one of the existing cable loom glands in the bulkhead - push a stiff wire (coat hanger) alongside the existing loom, from which ever side you can reach of the gland. Then attach your power wire to the end of the draw write and pull it all through.

Have to just be careful not to puncture the loom etc.


Active Member
Jul 6, 2019
there is a grommet in the firewall already large enough to take 1/0G cable, that's what I fitted.. you need to remove glovebox and pull carpet up a but to reveal it, maybe remove sill/kick cover too (would need to do that anyway to route cable through.

in the engine bay you can just reach the grommet behind/under battery, can't remember if I actually removed battery or not!



Active Member
Jan 29, 2019
Athens Greece
This what you're looking for. The photo is from my LHD car but I guess it's the same with RHD cars as well. Imagine this being behind the clutch pedal of a LHD car.


Coat hanger is the way to go as mentioned above. Battery can stay in place. You don't really have to remove it.


Mods mods mods
Staff member
Mar 24, 2015
Ilkeston, Derbyshire
I covered this on a RHD car in one of my guides, here's an extract regarding this:

Routing the loom
The next task is to feed the loom into the interior cabin. There is a rubber grommet behind the battery we can use to do this. You need to access it from both sides. From the engine side, you can move the battery forward and gain just enough access without having to remove the battery. You can remove it if you prefer, it will grant more space to work with, but I didn't want to fuss of removing it and having to reset settings etc on the car. It can be done by just moving it forward while still connected. To move it you need to remove the holding bracket, which is secured with a 13mm bolt:

Pull the battery towards the front of the car as far as it will go.

Now you need to get access from the inside. Start by removing the lower panel in the passenger footwell. It is secured by 3 torx screws:

Then, looking up towards the left, there is some insulation you need to remove. After you will see cables running through the rubber grommet already. This area is confined and hard to work in, so patience is key. Use your hands to feel for the grommet and the existing cables. Once you have found/located it, you need to pass some spare cable/string through it to establish a route. Use a generous amount to work with. I used a stick and taped the spare cable to it. I pushed it through the rubber grommet and into the engine bay. This is the view from behind the battery:

The red thing you can see is the stick poking out of the grommet. This part is also tricky and may take time. When you've got it through, attach the wires from the washer jet loom and pull them into the cabin, then route the remaining cable around the back of the battery, and refit the battery & bracket.

As Stefan said you haven't got to remove the battery, I loosened the retaining bracket on mine and moved it forward to allow more space to work with but you can get away without doing this.


Active Member
Jul 6, 2019
if anybody is worried aberyout loosing settings when removing battery you can always connect up a 12v supply to the negative post on firewall and directly to one of the M6 positive posts in the fusebox, using something like a Ctek trickle charger with 7amp power supply is enough to keep the car OK but don't try to start it without battery! I did this when upgrading the battery terminal to take the 1/0G cable.
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