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Headlamp relay, wiring and fusing


Adrian
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Hello all, just a quick one. I’ve read a number of online threads relating to the wiring and fusing of retro fitted headlamp relays. Some say have the relay close to the headlamp units, others say close to the fuse box. They seem to suggest a single 30 amp feed but others say split it to two 15 amp feeds. Typically I know any fused relay is an improvement on the original but just wondered what you thought.

thanks

Adrian

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I have a pair of relays tucked up behind the NS headlamp bowl. (spitfire) and they don't seem to be suffering from dirt/water ingress despite extensive use in all weathers.

I ran a single power feed cable to them,  "bundled" within the std loom. The existing feeds trigger the relays.

With the relayed power supply, crystal lamps and philips extreme bulbs the lights are superb. Difficult to way what the biggest improvement was out of the 3, they all helped, but relays have the added advantage of preserving the light switches.

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Location of the relays is largely irrelevant - you will always have a power feed from the battery so there will be volt drop however you do it - but for ease of switch wiring local to the headlamp bowl has to be a good option - just make sure the common feed (if you have a common and don't run a feed to each lamp) is man enough to take the load of two lamps (V=IR will give you your volt drop)

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Got the same sort of eBay kit as Doug and Clive on my Spitfire.  Rather than doing any drilling to the headlamp bowles I just cut the H4 plugs off the kit and added bullets to connect to the standard headlight wires where they join the car loom.  To mount the relays I used the grill mounting bolts.  Been there a few years now and not noticed any corrosion.

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You have to plug the single male H4 into one of the female H4s off the back of the head lamp. You could use one off the cut off H4s and crimp it to the old wiring but that's 3 crimps for each lamp plus 3 more for the male control from the switch. That's a lorra, lorra crimps. Perhaps solder and shrink wraps would be better.

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  • 1 month later...

Dave no, one kit does both. 

If you look at the picture there's a relay and a female H4 for each headlight plus one male H4 to interface with the original wiring. I cut off the H4s and used bullet connectors.

My brother also bought one and managed to source some unmade up H4s. He cut the head lamp wires and put on the new H4s to interface with the kit.  A much neater job than mine, God damn him!  :angry:

Doug

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The kits I got did high and low beam. There are some that do just one... but as Doug points out, that kit does it all.

My one tip, spray some waxoil/grease/chain lube over the terminals for the relays (unplug, spray liberally, push back in), and indeed the plugs for thelamps etc. I had a kit that failed, and the connections were rusted solid. Luckily I bought a spare kit, so easy enough to swap over. and this time sprayed everything. Seems to have done the trick. (this is a car that is left outside, used all year etc so cars that rarely see rain etc will likely be OK, but for the small effort, not a bad idea)

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  • 3 weeks later...

Hi,

On 03/12/2018 at 13:16, dougbgt6 said:

My brother also bought one and managed to source some unmade up H4s. He cut the head lamp wires and put on the new H4s to interface with the kit.  A much neater job than mine, God damn him!  :angry:

I'm hoping to do the same as Doug's brother and put some H4 male plugs into the headlamp wiring to match the female sockets in the kit. Does anybody know the orientation of the Main Beam and Dip Beam terminals in the existing socket on the back of the bulb? Imagining that the photo below is of the headlamp socket, I think that the terminal at 3 o'clock links to the black earth cable in the headlamp loom, but don't know which of the other two is the Dip (blue and red) and which is the Main (blue and white). Once I know those I can wire up the new plugs accordingly without disturbing the headlamps themselves. I know I could remove the headlamp to look, but I'm being lazy! If anybody knows, I'd be grateful

Wayne

 

IMG_1413.JPG

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Yes, I agree with Colin. In the kit earth is blue, the other two are red and black, main and dip, but which is which? As I was using bullet connectors which could be "reassigned" I arbitrarily connected red to blue/red and black to blue/white which turned out to be right.

Doug

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  • 1 month later...

Yes second kit is for 4 x 5.3/4"  lamp  set as in vitesse /2000

All these kits are a good way to save a lot of messing about there is only one snag you cannot fit the blue 3 pin bulb plugs through the hole/grommet in the lamp bowel,  so you either add lucars to the orig wires and just plug in or its a cut  , refit   , rejoin   

Getting 12/14 to the old seal beams will make the glow worms awaken, you dont have to fit halogens untill the sealed units give up

Yes halogen are whiter brighter but its not imperative  or a must have , but all this makes a difference worth while

Pete

 

Pete

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just doing a post purchase shake down of the car and theres an issue with the headlights - when i pull the switch out on the dash the side lights come on, then as I use the column switch the headlight is the inner light which Im guessing is main beam and the outers remain off. The outs glow when main beam selected but an orange glimmer rather than a bright light. when i use the flash the inner lights flash. confused as to where to start - any pointers gratefully received

 

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first check all the units actually work , so youre not chasing a failed filiament

earths are most important , odd glowing sounds like earthing needs attention

column switches do degrade the small rivet contacts and the sweep plate are often cooked ,worn or corroded , its worth a close look see.

and yes outers should    dip and main.........  inners just main 

pete

 

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Earths and old lamps always a nightmare, on my Vit6 we ran a earth bonding cable to co join all the rear lamps body tub to chassis

Body tub to baulkhead  and front chassis and bonnet , no more rusty panel joints to drag the voltage down,

Somethingnto add when all other jobs are done ...if ever  Ha!

Pete

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  • 3 months later...

Just about the try to fit the relays that Doug mentions earlier in this thread.  I intend the cut off the two yellow H4 connectors and solder bullet connectors in their place to connect directly to the respective headlamps. I will then use one of the cut off yellow H4s and solder bullet connectors on to that to link in with the mail loom. I assume the red wire is a permanent live (with or without the existing fuse) and that the blue goes to a suitable earth point . I am no auto electrician so if this is wrong can someone correct me please. This kit is probably simple but there appears to be a lot of wires!!!

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Badwolf, I gave up with the idea of these kits and used Andy Cooke’s blog, this gives a new fused supply to each light. On the vitesse I added 4 relays (1 for each dipped headlight unit and 1 for each set of main beam) it was a bigger job than I expected but I’d inherited a dodgy earth connection which this did away with. 

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BW,

That's exactly what I did, a lot of bullet connectors required, but hidden in the lip of the bonnet.  My brother bought the same loom for his Spitfire but he sourced the male and female H4s and put those in, a much neater solution, as he keeps telling me. :angry:

I've seen Andy's, 4 relays seem a lot, but hey, my modern's got relays for EVERYTHING. :lol:

Doug

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