# How to *properly* upgrade headlights to full voltage relay system. (MK2 Jetta)



## adhdcanuck (Nov 15, 2010)

OK So my goal was to run my low beams off the dash switch, have them OFF unless i had the switch turned on, and to use the high beams as normal. I exchanged my Old square lights for a new grille with quad rounds, you can do this the same way with the old lights, same process applies. I'm an electrician, so this was very frustrating but also a lot of fun. These represent best electrical practices for good connections. 

For any wire carrying power I suggest Red #12 Wire
For switching & grounding for lights you should use Black #14 Wire. Use proper wire not cheap radioshack stuff. Go get automotive hookup wire from Partsource or something. The insulation will be better, and the wire will be easier to work with. Its called primary wire, if you have better stuff use it, but as a minimum use that. 
As always make sure you use a good ground. I increased my wire size for the negative battery terminal to the block and added an extra cable grounding to the frame. This means ANYWHERE i tap into metal on my car is an awesome ground now. I also have a very well secured to the frame ground distribution block but you don't have to go that far.

The stock headlights are square and come with a High beam and Low beam wire to each.
I put in quad rounds.. Big rounds for low beam, small brighter ones for high beams.
Basically ran new power from the battery to the PWR connection on each relay (1 relay each for HI and LO sets), then ran power wires out from the relays to each light (2 outputs per relay, so 2 bulbs each).Instead of running two #12 wires for the power I ran a single #8 gauge and split off it, cleaner I think, easier to fuse, and this is how you properly splice multiple small wires off one larger wire safely.I had it laying around to use up.

Switching was the hard part.
High beam was easy, just identified one of the wires for High beam (Yellow wire on passenger side) and put it to the switching terminal on the HI relay. tucked the same wire (Black/Yellow) on other side back into the harness out of the way, no longer needed. The high beam wire is an ON/OFF situation, direct from the steering column switch.









LO beam was a pain in the ass. The MK2 Jetta uses an "always on" headlight system on lower voltage as daytime runners. Impossible to disable, despite reports of some kind of dim/dip coil for the golf it does not apply to the jetta. The power wire to the Low beams gives voltage anytime the ignition is on. When you push the headlight switch it just adds a circuit and gives it higher voltage. So you might read ~10v with the switch OFF then ~11.5 with the switch ON. Hence all the dim headlights even fully on.
So if you use the low beam wire to switch the relays the headlights will come on as soon as you turn the key and stay on full always. Thats fine if you want headlights on all the time but I wanted mine off, so I could control them and save battery power.

I hacked into the *only* wire on the back of the headlight dash switch that is ON/OFF, every other wire is either ignition, pass through, dimmer, or connected to other stuff. It is a GREY/BLACK wire. See image. I used Spade connectors to securely tap into it and also connect the original wire back together so as not to interrupt the circuit for anything else thats on it. Added tape after to secure and insulate the connection. No need to solder.
I ran a fresh wire through a hole in the firewall (behind and to the left of the brake booster, theres a couple you can use or just make one) and attached it to the relay for the Low beams on its switching terminal. The yellow/black wire I also cut into is IGNITION direct to the key switch. I needed it for something else. The little grey/black wire next to the little yellow wire on the bottom of the switch is what you need.









All the wires hid nicely, the relays and all their wiring fit behind the passenger light, in front of the airbox almost impossible to see. I ran them around the battery, under the fan/radiator and up by the other rad hose. Protected, clean, invisible.









Instead of running two wires for the power I ran a single #8 gauge and split off it, cleaner I think, easier to fuse, and this is how you properly splice multiple small wires off one larger wire safely.









Then wrap it in insulating rubber tape (or GOOD electrical tape) followed by a layer in the colour of your choice. It will never move, never give a bad connection, and always be serviceable. 
Like this:










Now my factory controls work like normal and my headlights are super bright. 

VW Has issues with wiring loom sizes on MK2 and probably 3 as well. The wires are too thin and long. My headlights were drawing 10.2v originally off a fully charged battery, now theyre getting 13.5v and are plenty bright.

Extra tips:
-Use proper criming tool to put spade connectors on wire, and add a drop of contact cement to the back part so it stays on the wire really good. If you are putting them on a relay terminal slide heatshrink over the whole thing after and it will hold tight forever but still be removeable with a knife if needed.
-When soldering use plenty of heat and when done use either two layers of heatshrink, or one layer plus a good wrap of electrical tape.
- When your relays are wired up and ready to hide, put them in a double baggie (two sandwich bags trimmed to cover just enough) then tape the end up good onto the wires for a relatively weatherproof seal. 
- Use ty-wraps (zip-ties) to secure your wires everywhere as you run them through the car. If it doesnt move, or get very hot it is fair game to ty-wrap it to. The less wiring you have in the open the more protected (and better looking) the install.
- If you need something to be removeable (like the grille with new wires going to it) use spade connectors and tape them up when theyre secure.
- Test everything three times, then once more. 1) with power off 2) with key in run position 3) with key in off position again, then take a look to make sure your power and grounds are all good and check with power on one more time. That saved me a couple screwups.


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## BiH (Nov 27, 2000)

I didnt know mk2's had DRL? mine are off-on only and city lights as parking lights. I need to do this as well soon. where do you get wire terminals and such?


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## cuppie (May 4, 2005)

OP's in Canada - they've mandated DRLs for quite some time now. We in the States didn't get those. 

Another option for the parts needed: order a kit from Daniel Stern Lighting - that's where I got the kit to do my 'rocco. 
You'll get dual-output relays, relay sockets & pins, fuse holders, headlamp connectors & pins, male connectors (to connect to the factory wiring), and ring terminals (for the battery connections) - literally everything needed to relay the lights, save for wire, tape (for which I highly recommend 3M Commercial 300, as it's weather- and heat-resistant), zip ties, and (if you want) flex loom (get these items from the store.) 
Total install time: about 1.5 hours (spent, mainly, building the relay harness.) 
Value of not having to hunt down parts: priceless.


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## gti_matt (Oct 9, 1999)

1990-1002 Mk2s had DRLs in Canada since 1990+ model years were required to have DRLs.


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## gti_matt (Oct 9, 1999)

cuppie said:


> Another option for the parts needed: order a kit from Daniel Stern Lighting - that's where I got the kit to do my 'rocco.
> You'll get dual-output relays, relay sockets & pins, fuse holders, headlamp connectors & pins, male connectors (to connect to the factory wiring), and ring terminals (for the battery connections) - literally everything needed to relay the lights, save for wire, tape (for which I highly recommend 3M Commercial 300, as it's weather- and heat-resistant), zip ties, and (if you want) flex loom (get these items from the store.)
> Total install time: about 1.5 hours (spent, mainly, building the relay harness.)
> Value of not having to hunt down parts: priceless.


 Stern has all good parts, but on the flipside I like not having to build the thing either. Knowing that I tend to be a blit sloppy when building harnesses (I can fix existing or patch things well but building from scratch it looks like a hack job when I do it), I like just buying a pre-made harness even if the parts aren't the highest quality. It doesn't have to be military-grade for automotive use; it just has to *work*. To each his own though.


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## adhdcanuck (Nov 15, 2010)

im a huge fan of doing it yourself and not paying for kits especially for things like this... theres no need and unless its SUPER cheap theres really no benefit.

Except that its easier, but, thanks to the DRLs this would not have worked with a kit, no part of the factory harness was used from the original headlights here.

Because of discoveries like that, I find its best to do it all myself. I save money buying the parts usually, and i tend to do decent quality work. 

What that guy says about good quality tape is so true. Best tape on the market is 3M or Scotch electrical tape.. its called super-88.... soft and flexible down to 30 below zero and has a real electrical insulation value, unlike pvc/vinyl tape.

Having real rubber tape (the stretchy stuff) is handy for insulating power connections.

I buy my terminals on ebay, because at the local electronics shop I can buy a 50 pack for the same price as a 250 pack online including shipping. Hardware/auto parts stores are even more expensive.


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## T-redmk2ABA (Jun 9, 2009)

What kind if alternator do you have that you can jump a lead off the top


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