KrashDH
Top Post Dawg
I figured I would consolidate this into its own thread instead of updating the "what did you do to your Mk4.."
When I did my headlight retrofit, I custom wired the inside headlight harness for the functionality that I wanted it to have with all my extra goodies. I put led bulbs in the projector housings for the fog lights, but it was a very back burner project
Now that I wired the gauges in and ran stuff through the firewall, decided it would be a good time to run the fog light trigger wires and such too.
On the euro switch, fog position 1 will be headlight fogs, and pos 2 will be the in bumper amber/yellow fogs. I could have been done, but I decided I didn't want relays all over the place. Plus I already have some extra wiring from my morimoto harness, the under hood lights, and the addition of a BEW lift pump.
I ordered an auxiliary fuse/relay box and am going to send both sets of fog lights throught relays in there (even thought both draw such little current). Its got spots for non relay fused power as well, so I'll send my under hood lighting to there as well. Headlight ballasts im going to keep directly connected to battery power (and the ground) just for peace of mind. Fuel pump power I'm not sure if I'll keep it directly to battery or go off the new aux box, I'll make a game time decision.
Aux box is supplied by 2x 12ga wires. I'm going to install an inline 40a breaker between batter pos and the aux power since the 2x 12ga wires I'll tie together in parallel can safely handle that. The side going from the battery to the breaker will have 8ga which can also handle 40a.
So for some reason if something goes bad, the individual circuits are all protected by fuses and itlf it goes really bad, the breaker will trip (it's resettable)
I don't plan anything with massive current draw to be on this car, so 40A at the same time is plenty. I think the bumper fog light bulbs I have draw like 3A if that, and the ones in the actual headlight housing are around 1A. The under hood lighting is about 1A, the fuel pump is (?). I'm well within the parameters.
Here we go.
While I was waiting for things to get in, I made my Euro trigger harness that goes from the back of the switch to whichever relay trigger wires. I'm using the "front" fogs for the in-headlight trigger and the "rear" fogs for the bumper fogs that are on the way:
Here's the pins inserted, looking back I probably shouldn't have put the shrink tube on there, it's got a glue adhesive liner and they were a snug fit in the slots:
I ran the wires through the firewall with the other wiring from my gauge install, ran it along the parking brake cable housing, and terminated it between the gap between the battery and airbox. This is where I decided everything will come together:
I searched for a while for what fuse/relay combo I wanted to mount in there. I knew where I wanted it to go, so I found this pre-made box on Amazon and the dimensions seemed like they would work well:
This car isn't going to have a ton of accessories. Both sets of fogs are going to be run on relays, and there will be 2x spares if I ever need them for other goodies.
As can be seen above, it also has the fused slots if you just want power out to an accessory. This was nice for me because I have some underhood lighting that could be run on a standard fused slot, and I opted to move my lift pump power over here too to get it off of the battery. I left my ballasts for my HID's connected directly to the battery since if for some reason the breaker ever tripped, I'll still have headlights (but no lift pump, so I may run it like this for a while but if it's a problem, I'll revert back). I shouldn't have any reason to trip the 40A breaker though.
Now, since I removed my catch can setup, that freed up the left side of the battery, which was holding the catch can bracket prior. I decided a similar bracket could be utilized for this box setup, so I repurposed the L brackets I made for the catch can, added a thing metal "book end keeper" for stability, then added a layer of kydex (used for making holsters) on top of that so the fuse box was against plastic rather than metal. Probably didn't need to be, but this worked out well:
The 2x middle holes are from my catch can mount, the new ones in the L brackets are for the spacing of the fuse box mounts:
After a bunch of futzing around, I had my basic assembly together. You can see the resettable breaker on the top left of the image:
Ran the 2x power supply wires to the breaker on the bench for ease of install:
After removing the bottom-most relay, I was able to sneak the L bracket down through the gap between the coolant line and the battery, and slide it underneath the loosened battery. I tightened the battery back down, and now you have a solid mount that isn't going anywhere:
Test fitting to see if I could get the cover in there. I did as you can see, but it took some Tetrising around the coolant line:
When I did my headlight retrofit, I custom wired the inside headlight harness for the functionality that I wanted it to have with all my extra goodies. I put led bulbs in the projector housings for the fog lights, but it was a very back burner project
Now that I wired the gauges in and ran stuff through the firewall, decided it would be a good time to run the fog light trigger wires and such too.
On the euro switch, fog position 1 will be headlight fogs, and pos 2 will be the in bumper amber/yellow fogs. I could have been done, but I decided I didn't want relays all over the place. Plus I already have some extra wiring from my morimoto harness, the under hood lights, and the addition of a BEW lift pump.
I ordered an auxiliary fuse/relay box and am going to send both sets of fog lights throught relays in there (even thought both draw such little current). Its got spots for non relay fused power as well, so I'll send my under hood lighting to there as well. Headlight ballasts im going to keep directly connected to battery power (and the ground) just for peace of mind. Fuel pump power I'm not sure if I'll keep it directly to battery or go off the new aux box, I'll make a game time decision.
Aux box is supplied by 2x 12ga wires. I'm going to install an inline 40a breaker between batter pos and the aux power since the 2x 12ga wires I'll tie together in parallel can safely handle that. The side going from the battery to the breaker will have 8ga which can also handle 40a.
So for some reason if something goes bad, the individual circuits are all protected by fuses and itlf it goes really bad, the breaker will trip (it's resettable)
I don't plan anything with massive current draw to be on this car, so 40A at the same time is plenty. I think the bumper fog light bulbs I have draw like 3A if that, and the ones in the actual headlight housing are around 1A. The under hood lighting is about 1A, the fuel pump is (?). I'm well within the parameters.
Here we go.
While I was waiting for things to get in, I made my Euro trigger harness that goes from the back of the switch to whichever relay trigger wires. I'm using the "front" fogs for the in-headlight trigger and the "rear" fogs for the bumper fogs that are on the way:
Here's the pins inserted, looking back I probably shouldn't have put the shrink tube on there, it's got a glue adhesive liner and they were a snug fit in the slots:
I ran the wires through the firewall with the other wiring from my gauge install, ran it along the parking brake cable housing, and terminated it between the gap between the battery and airbox. This is where I decided everything will come together:
I searched for a while for what fuse/relay combo I wanted to mount in there. I knew where I wanted it to go, so I found this pre-made box on Amazon and the dimensions seemed like they would work well:
This car isn't going to have a ton of accessories. Both sets of fogs are going to be run on relays, and there will be 2x spares if I ever need them for other goodies.
As can be seen above, it also has the fused slots if you just want power out to an accessory. This was nice for me because I have some underhood lighting that could be run on a standard fused slot, and I opted to move my lift pump power over here too to get it off of the battery. I left my ballasts for my HID's connected directly to the battery since if for some reason the breaker ever tripped, I'll still have headlights (but no lift pump, so I may run it like this for a while but if it's a problem, I'll revert back). I shouldn't have any reason to trip the 40A breaker though.
Now, since I removed my catch can setup, that freed up the left side of the battery, which was holding the catch can bracket prior. I decided a similar bracket could be utilized for this box setup, so I repurposed the L brackets I made for the catch can, added a thing metal "book end keeper" for stability, then added a layer of kydex (used for making holsters) on top of that so the fuse box was against plastic rather than metal. Probably didn't need to be, but this worked out well:
The 2x middle holes are from my catch can mount, the new ones in the L brackets are for the spacing of the fuse box mounts:
After a bunch of futzing around, I had my basic assembly together. You can see the resettable breaker on the top left of the image:
Ran the 2x power supply wires to the breaker on the bench for ease of install:
After removing the bottom-most relay, I was able to sneak the L bracket down through the gap between the coolant line and the battery, and slide it underneath the loosened battery. I tightened the battery back down, and now you have a solid mount that isn't going anywhere:
Test fitting to see if I could get the cover in there. I did as you can see, but it took some Tetrising around the coolant line:
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. At least half of the cars I see coming to me either are missing the screws or the mount plastic there has been so torn as to be useless. 