Headlight relay fitting for dummies!And

johnk

Member
Hi, I'm planning on fitting relays to the headlights on my 1972 2000tc to take the strain off the fuse box but being a bit of a dummy where electrics are concerned I'm hoping someone with more knowledge will confirm my intentions or point out why if it's not correct.

I've bought a 4 pin 30a relay which i intend to wire as follows;

Supply 30. Live feed from the battery
Switch (live) 86. Blue/red wire from loom
Earth 85. Direct to Earth on the chassis
Accessory 87. Blue/red wire to the light.

Is this correct? If so I assume the earth wire from the light unit still connects to the earth in the loom. Being a 30a relay can I wire both dip beam lights through it? I intend to fit separate relays for the main beam also. Is there a convenient continuous live feed in the engine bay that's easily accessible?

Thanks,

John.
 
In a word....yes.

Connections 85 and 86 are the relay coil and require an earth on one connection, and +12V on the other to operate.

Connections 30 and 87 are the relay contacts, so 30 is the supply, (+12V in our case), for whatever you want to operate, and 87 goes to the item being operated, in this case the lights.

I did this addition myself, and is a sticky topic in the reference section:

https://classicroverforum.net/index.php?threads/headlight-relay-conversion.35168/

I used the live feed from the back of the alternator, which easy enough to get to.
 
Thanks for the reply, Ive had a look at the sticky and I think I'll need to forgo my crimped connectors and invest in a soldering iron to do the job justice!
 
I used crimp connectors and they are fine. I did however use four relays to run the lights.

1/. N/S dip
2/. O/S dip
3/. Outer full beam
4/. Inner full beam.

I did it this way because if one of the relays failed, I wouldn't lose both dipped lights at once; or if on full beam, I wouldn't lose a complete side.

Then it was just a simple wiring job, one bit at a time.

Find a place for the relays and fit them.

Take the wires that feed the headlights and connect them to 85 on the relays to turn them on.

Take four wires from 86 of the relays to earth. Now when you operate the headlights, the relays will fire instead of the headlights.

I spliced into the wire from the shunt to the headlight switch and ran a wire down each inner wing to 30 on the relays, jumping one to the other to get all of them live.

Then 87 from the relay goes to the headlights to run them.

Whenever I do any non standard wiring I always make up a small wiring diagram so I know what I have done in a few years time (Sometimes it's only a matter of days at my age ;))

Here it is.

after.jpg

Richard
 
I would be tempted to fuse the main feed to the relays, just in case a short occurred in the new installation or headlamps.
 
Hmmm,, I fitted unfused relays.... Oh well, a trip to halfords tomorrow then!

I took my supply from the starter relay as its on the inner wing on the 2000 and the loom runs from it to the lights.

Do I need to change the fuse in the box now for something lower? If I check the current across the fuse will that give me an idea of the new rating?
 
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