Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Relay needed to wire fog lights on a '65 Plus 4?

Hi all,

Getting ready to wire the fog lights that I recently installed on my 1965 Plus 4..

I'm installing these Lucas replicas from Moss Motors.

I was able to locate the red/yellow trace wire that runs from the dash toggle to the front of the car (it is currently disconnected from the dash). When looking at the factory wiring diagram, it appears the hot (red/yellow trace) wire from the toggle is simply split with a snap connector and then connected to the foglamps (which I plan to ground to the chassis.)

I plan to add a 10 amp inline fuse to the hot (red/yellow trace) wire before the snap connector...question is, do I need a relay as well?

Looks like the factory didn't even fuse the foglamps - is a 10 amp inline fuse sufficient protection?

I know that a relay is often recommended - but it seems that's the case for more modern, electrically demanding, Morgans.

Any advice is appreciated.

I always install relays for the lighting.
Head lamps, high beam and low, route through the stalk switch. Toasted those contacts more than one. Last time I replaced the stalk switch I wired in two BOSCH light relays. hardly any amperage to pick the armature. Contacts rated for 20-30 amps. No worries.
Your fog lights are probably going directly through your dash switch. Gets hot, contacts fry. Put in a relay.

Been there, done that. Live and learn. Don't lose your lights at night!

Ron Davis

Thanks Ron - any recommendation on what type of relay to use? I have a 4 contact relay for the horn on my Alfa - are they all the same if they have the 4 contacts (85,86,87, 30)? Was planning on jumping 85 and 30 together, connecting the wire from the toggle to 86 and connecting the lights to 87...diagram below:

That's not quite correct crowbar. 86 is relay coil positive. 85 is coil negative to ground. 30 takes your fresh fused feed from battery and 87 is that relay switched feed out to lamps.



Generic 4 or 5 pin cube shaped 12 volt 30/40 amp relay will work fine (ignore 87a contact on 5 pin).

So this is the relay I was going to use:

Headlamp Relay

So looking at the above diagram and comparing my wiring plan (hand drawn) above:

So is this an appropriate plan?:

1) Red/yellow wire from toggle switch connects to 86
2) Long wire direct from +battery terminal connects to 30 (with an inline 10 amp fuse) - is there a closer location from which I can draw power (from the control box?) rather than running a wire to the battery?
3) 85 Grounded to chassis
4) 87 Connects to foglamps

Many thanks all!

Agree with your current proposals. Terminal A1 on the regulator feeds the lights (brown/blue) so you could tag onto that with an inline fuse.

So I wired things directly as described in Richard V6's very helpful diagram - but I'm blowing fuses immediately - started with a 10 amp fuse and went up to a 35 amp fuse and the fuse blows immediately when flipping the dash switch. I do hear the relay clicking when I throw the switch - so that seems to be working...should I go to a higher amperage fuse? The fuse really pops when it blows...

I drew the power for terminal 30 on the relay directly from the terminal on the ignition cutoff switch that the PO installed in the footwell. I combined both the red wires for both foglights onto the spade connector at terminal 87 on the relay...

I was pretty meticulous with the wiring, all connections were soldered and shrink wrapped. I used one snap connector and soldered bullets to connect the existing yellow/red wire from the switch to the red wire to terminal 86 on the relay. I used this 40 amp Bosch relay

When wiring the foglights I wired the red wire to the contact that touches the bulb, and the black wire to the contact that touches the foglight shell/body.

Shouldn't be the grounds - they're all on soldered eyelets to sturdy bolts/nuts on the radiator supports.

I seem to have a short somewhere...can't figure out where. Unless even the 35A fuse is too small...should I jump the inline fuse as a test? (could let the smoke out...) The fuses I bough from Amazon were from overseas and very cheap for a large selection...

Would appreciate any thoughts from the group...

Best,

GC

Sounds like a short . You need to find it . Don't keep blowing fuses.

Maybe the relay is faulty. Try going back to the rated fuse and bypassing the relay. If it works there is your issue

You do not need a 35amp fuse! Your bulbs should be 55 watts which is, using dear old Ivy Watts, is about 5 amps for each bulb (I x V = W) giving you a total of 10 amps. Anything larger than a 20 amp fuse is way too much.
As John says above you have a short somewhere.

Although the wiring diagram showed a negative earth system, being a 1965 model, it’s not a positive earth system by any chance? In which case, the diode would be reversed! Double check battery connections to see which pole is connected to earth.
If thats the case, then 86 needs to ground and 85 the input from the switch.