Hi,
Looking for advice for fitting lightbar to Volvo FH12 version 1. Lightbar will have 4 Hella 3000’s. Just wondering is there fuses/relays already in place to connect into,with loom in dash for switch? Have wired in beacons on FL10’s where loom was in place, just to add switch with connecting block behind panel.
Or just take feed from mainbeams/parking lights through relay fuse and switch. Should wiring be split with 2 connected to left and 2 to right circuits? Anyone got circuit diagrams available?
Have seen some crude installations with feed taken from mainbeam on oneside to 4 spotlights with no relays or fuses. Also sorted out some very dim worklights on a FM tipper that were wired into the 12v radio circuit!
Thanks in advance for your replies.
Hi Skelly,
once youve fitted your lights run your cable through a hole that you need to drill, ideally near to the interior light on the passenger side of the roof (that way you can reach the cable without having to take all the headlining out) need to use a good grommet to make sure its water tight.
Then feed your cable down behind the plastic on the door pillar and across to the centre of the dash.
For the main beam signal wire to the relay, you just need to identify the wire at the headlight, and follow it back to the cab,take off the long black plastic cover(yes the one that says do not remove) behind the grill that protects all the electrical harness plugs, this makes it easier to identify the correct harness, as sometimes the wires change colour when they go through a plug. (very helpfull!!).
If you go to volvo and ask for Fitting Kit-20569981, this has all the bits you need plus some you dont (wont be cheap).
If you need to wire side lamps in your lights you can pick up a feed straight from a roof marker lamp which will already have a fuse in its circuit.
Be carefull if you have 100w bulbs in your lamps coz you’ll need some robust cableing. 
Hope this helps, sorry if its a bit sketchy, it was 2004 when i did mine. 
Mike,
Thanks for reply. Yes I would like to trace main beam signal to relay/switch from under dash rather than routing more cable from back of headlight. Will use entry point as suggested above interior light, also use this for cable to strobe beacons. Will be using 70w bulbs.
Regards,