IDIOTS GUIDE TO HEADLAMP RELAY MOD

[Gunslinger]

Is there one, ie, which relays to get, do they need wiring directly to the battery or a feed off of the fuse box etc.
I have read the wiki and could probably sort it but more info would give me a little more confidence

Thanks
Stuart

[Titus A Duxass]

This is what I'd do (have done):
1. Run a big wire from the starter battery (I used two 6mm for redundancy and because it was free). Don't forget to fuse it near to the battery (15amps). I my case it was from the rear battery and runs alongside the waterpipes over the tank and up behind the grill(s).
2. Get some 30amp normal 12v car relays (Now you can either have one relay for dip and relay for main fed to two lamps or 4 relays. One each of dip and main for each lamp).
3. Grab a handful of quality crimps and a good crimping tool.
4. Find a suitable place to mount the relays (close to the lights is good).
5. Wire them up. Piggy back the leads where you can (I did this with the positve and negative (earth) feeds.

[Titus A Duxass]

I meant to say that the hardest part is breaking into the exist lamp feeds and connecting them to the relay driver coil.
You could, if you wished, grab some lamp connectors (plugs) with a good bit of loom attached and piggy back them alongisde your existing lamp connectors.
That way you have a fall back if the relays fail (unlikey as a relay has a good failure rate).
Or you could cut into the existing loom and use the existing connectors, which is what I did.

[Titus A Duxass]

With no particular preference (Maplin is easy to remember).
Maplins for relays - N03AW - 30A SPDT Automotive Relay
Likewise for the cable - CK17T

Merlin for the fuse box - Grayston GE71 4 way Fuse Box.

[Gunslinger]

Thanks Titus, I'll be giving that a go then.
So 1 live feed from battery to 4 way fuse block near battery (under drivers seat), 4 lives to 4 relays behind grilles, wire into existing lamp connectors at lamps.
Does that sound about right?

[Titus A Duxass]

About right, feed the 12v to the first relay then piggy back it to the next (you can get double crimps for this).
That leaves you with spare room on your fuse box.

Here's a link to a crappy sketch that shows what I mean:
http://t3-infos.de/images/SW-Relais-Skizze.gif" onclick="window.open(this.href);return false;

Abblendlicht = dip beam
Fernlicht = main

Zusatzlampen = any other driving lights/spots

[Gunslinger]

That diagram is very useful thank you.
Just one query, earlier in the post you mention a 15 amp fuse but your diagram shows a 50 amp, is this because there are 4 relays?
I presume 4 relays is better than 2?

Should I replace all the lighting wiring to switches etc for heavier duty or is that not necessary?

Thanks again
Stu

[Titus A Duxass]

15 amps is enough, I've been running with 15 for 4 years. (50amps is OTT).
I don't why the diagram has 50amp, the Germans do tend to be a bit OTT.

Four relays are better than two, better distribution of power and built in redundancy.

Don't touch the switch wiring.

Simply put, you are taking the current (voltage) that, at present, goes directly into the bulb filaments and using it to switch a relay.
This relay switches 12v direct from the big battery feed direct to the bulb filaments.

On a none modified circuit the 12v to the bulbs comes through the van wiring and switch gear.
This path and the thickness of the standard wiring causes a voltage drop at the lights (dim lights).
By taking a direct feed from the battery via a thick wire (6mm or thicker) via a relay you do not get the voltage drop at the lights (brighter lights).

[Gunslinger]

Thats perfect. Thanks for the advice.
Guess what I'm doing this weekend?

[Red Westie]

4 relays....why on earth would you want four relays when there is only a max of 20amps flowing?
2 relays, one for full (say 40amp type) and one for dip (30amp is plenty as this is only carrying 10amps)
There is also a major flaw in your diagram, one heavy 6mm wire with 50amp fuse feeding 4 lower rated circuits means if any of the lighter circuits short out their wiring will melt causing a possible electrical fire rather than blowing that heavy fuse (that is unless all your feeds and earths are going to have 6mm wire and appropriately rated terminals and relays) Fuse on each circuit needs to be rated lower than the wire used on that circuit.

Given that you propose to have these relays open to the ellements I suggest:
Soldering and not crimped connections
Terminal shrowds
Relays mounted terminals down
And some sort of water splash cover over the relays and terminal ends.

Martin

[Gunslinger]

Is 18 amp cable ok with a 15 amp fuse?

[lloyd]

Had a very knowledgeable electrician mate do mine and we wired from headlight plug to relays... used 3 relays as have quad headlights (dipped on one and one for each pair of highbeam bulbs). All new harness with plug ends from relays to lights. Fused each lead from relay to lights. Main power from original fuse block power. Wiring runs from left light into fuse block area, relays and new fuse block mounted on metal vent duct to door, then wires go back to left headlights with new plugs and over to right lights with new plugs. If any problems ever arise I can unhook plug for original left headlight from new harness and plug it back into headlight.. unplug new harness from other lights and plug in old harness. Back to stock.

He put an extra relay in for future fog/driving lights.

We didn't take any pics of project as it was a Dubfreeze last spring... and it was cold and windy. Had to eat bacon egg baps during and big bowls of chili afterwards around fire... with plenty of consumable antifreeze. Fantastic difference!

[Titus A Duxass]

A) It's not my diagram I placed the link to show the piggy backing of the power line.
B) I did say that 50 is OTT, I have 15amps in mine.
C) Four relays gives an amount of redundancy in the system. On a two relay circuit one relay failure means the loss of both headlamps and running lights through one means the surge current at the switch transition is near peak and could lead to arcing which in turn could lead to sticking relays.

Crimped connections are more than adequate if done correctly and a piece of heatshrink over the crimp gives enough weather protection.
Naturally the relays should be mounted with terminals down.

[bigherb]

Yes four relays should be used for safety the same as four fuses are used, if one fuse or relay fails you are not left without any light when you most need them. And for the same reason running two induvidually fused wires from the battery to a pair of dip and main relay rather than one. Having four relays and one feed is defeating the objective.

[richnewton]

have a look on the samba aswell

http://www.thesamba.com/vw/forum/viewto ... mp+upgrade" onclick="window.open(this.href);return false;

pm'd ya gunchucker