Relay upgrade for Square Headlights - problem!!!!

Post by **VWlewis** » 25 Sep 2007, 17:35

Having spent too many hours trying to sort this out

I am asking for some help!

The low beam headlights are powered with yellow and black/yellow wires (LH and RH side respectively). I cut the wires on the output side of the fuse box and used them to drive the relays - the other side was connected to ground to complete the circuit. I ran a new power feed from the battery (via a fuse) and connected this to the relay power inputs. The relay output power lead was connected to the yellow and black/yellow wires going to the headlights.

Having done this, checked and re-checked, I measured the voltage coming from the fusebox in the yellow and black/yellow wires. I noticed these show 11.49volts when the ignition is on and the side light switch is on. This means the relays cut in as soon as the light power switch is turned on to sidelights when the engine is running, giving me dipped beam headlights. Then when I switch the headlight switch to dipped beam I get main beam lights coming on as well as the dipped beam.

Great lights

but not what I wanted and not legal!

Any ideas what is going on? Perhaps I have cut the headlight power on the wrong side of the switch but I can't see how as the wires definitely go to the headlights (I checked the resistance from the fusebox to the headlamp connector.

... Thanks

Post by **Westy.Club.Joker** » 25 Sep 2007, 18:00

Did you look on the Wiki for the wiring diagram for this mod? I followed the diagrams from there and mine worked fine. Not sure what you`ve done as it`s a bit confusing, but if you have a look on the Wiki for the electrical mods it may help you understand where its gone wrong.

Post by **VWlewis** » 25 Sep 2007, 18:11

Thanks for the direction to the WIKI - I have read all these documents - did you use the white & white/black wires or the yellow & black/yellow wires? - the white ones seem to feed the main beam and extra square headlights but one description I read talked about the white wires...

hmmm .. still confused!

Post by **Westy.Club.Joker** » 25 Sep 2007, 21:44

It was a while back, but looking at the Wiki diagram again (the one by Horace) --

white and yellow/black are the switched feeds to the relays

low beam power feed out of the relay goes to yellow and yellow/black on the 2 lights

main beam power feed from the relay goes to the white and white/black at the lights

On mine I powered the inner (main beam only) lights by using a piggy-back from the main beam relay switched feed (the white wire) to operate another relay just for the inner lamps, to avoid overloading the first main-beam relay, in hindsight I could have just used a heavier duty relay to operate all 4 main beam bulbs.

I cut the original switched feeds (white and yellow/black) BEFORE the fuses, and fed the relays with them, the new 12V power feeds to the relays are fused.

I would advise you to buy new bulb connector plugs (Vehicle Wiring Products do `em) and run new cables right from the relays to the headlights, getting rid of the old wiring completely and so not having to have any un-needed connections between power and bulb, which is the reason for doing it in the first place !

Also make sure you use heavy enough cabling and relays, in case you upgrade the bulbs to bigger wattage. 2 x 100 watt bulbs will draw nearly 20 amps, so go for 30 amp relays etc. That`s the reason I ran 2 relays for the 4 main beam lamps, 400 watts draws some current

Post by **VWlewis** » 26 Sep 2007, 07:19

Thanks Westy.Club.Joker ... just what I needed to know!

Sorted with the additional help from Mr Baxter - seems the dim dip resistor behind the right hand side light fitting needed to be disconnected and all was working beautifully .... can't wait for it to get dark now!