I've just fitted and wired up the Prodrive driving lamp kit as supplied for the MY03 blobeye (PIAA 130mm 600 series lamp).

So that I can safely run a higher wattage bulb I've made up my own loom rather than run it through the original fog lamp loom (basicaly the old loom I had running Cibies on the old classic).
I've wired them up to run via the fog lamp switch via a second relay so that they can either be on or off with the headlight main beam.

The problem I have is that I can't find a switch feed from the main beam (HB3 bulb) on the car to activate the lamps with main beam. There seems to be a constant live feed to the main beam.
I seem to remember on the old classic (H4 bulb) I just connected the relay to the main beam live feed to switch it.

Where can I find the switchable main beam feed for the relay, or is there some other wiring trick for newage scoobies?

 

you may be better changing the wiring to the foglight switch (I have done this) then using this to switch the relay.. I've got a wiring diagram somewhere I'll try and find... it just takes main beam power to the switch rather than dipped power....

 

There's a permanent live to one side of the bulb and a switched earth to turn it on and off (for some obscure reason).

Wire the relay coil to both sides of the bulb (terminals 85 and 86 on the relay) and you can't go wrong.

Or take the bulb out and see which side of the wiring is at 12V with the lights off and wire the other one to one side of the relay coil and the other side of the relay coil to permanent 12V. You have to take the bulb out when measuring otherwise both sides are at 12V with the lights off as you've no doubt found.

 

Thanks for the options guy's.
Chelspeed - If I understand your first method the two relays should work out something like this?

Main relay
30 - battery
87 - lamps
86 - from 30 on second relay
85 - earth

Second relay (for fog switch on/off control of lamps while on main beam)
30 - from 86 on main relay
87 - from +fog lamp
86 - main beam +
85 - main beam -

If not I'd appretiate any corrections.
Thanks

 

That sounds like it would work but you don't need two relays. One relay:

87 - to driving lamp +ve
30 - from +ve on fog lamp
86 - main beam +ve
85 - main beam -ve

And finally earth the -ve side of the driving lights. Should work.

 

That would take the main feed to the lights from the foglight switch/relay though? I'd far rather take it direct from the battery, via a fuse, using good quality thicker (28A) cable, and soldered spade connectors. Less chance of volts drop

Alcazar

 

True. But as you say there is a relay in the fog light circuit. So if the driving lights are 55W (the same as the foglights) should be OK. If off road use only (!) bigger watt blubs are planned for the driving lights then I'd agree.

 

I want to stick with the + feed direct from the battery for the added security with the 55w (!!) bulbs.

So if I use one relay and Alcazar's suggested + feed from the battery how do I get the switching from the fog light feed? That was my reasoning for the two relays.

 

If you want the direct feed then your original 2 relay approach should be OK.

Only change I'd make is I'd add a fuse in the new +ve feed from the battery to the first relay terminal 30 or in the wire between the relay and the lights. Or use a relay that has a built in fuse. For a pair of 55W lights a 15A fuse should be about right.

 

I'm using fused relays so it should be OK.
I'll try the new set up at the weekend and see how it goes.

Cheers for the advise.