Fog light wiring

[Collette Dobson]

The cappo has been getting a lot more use lately as our son is learning to drive in it, so it is also getting more TLC.
We have been fiddling around with the electrics fitting an LED in the high level brake light – I know it should have been done 20 years ago but it has just languished on the to-do list. Anyway got that done and am now looking at the other two things from that same list. 1) A timer on the interior light so when we accidently turn it on with our elbows we don’t end up with a flat battery, and 2) the problem that the fog light switch keeps the relay activated regardless of the ignition, with the same result.
I have been looking on the forum regarding the fog light – I am pretty sure Ian posted something years ago but I can’t find it. Is there any reason not to just move the feed for the fog light to a fuse that is only live with the ignition? It seems a simple fix but I am sure people have used relays in the past.
Any info much appreciated.

I tried to add a picture but don't know how to!!

[Ian Linden]

Hi Collette,

Good to hear the Cappo is earning its keep. The Foglight Scheme is here.

I don't recommend just moving it to another fuse, as you can then have the foglight on without other lights, which is, I believe, contrary to the Construction and Use Regulations. That could get you the Law's attention, and maybe fail an MoT? Come to think of it, that applies to how it was originally wired as well!

[Collette Dobson]

Thanks for that Ian. Good point about it working without the lights.
How do you post a photo on here? I click Img and get the start and stop markers for an image but can't see how to point to one. I vaguely remember you have to load it into the gallery but I couldn't do that either!

[Collette Dobson]

So the headlights are switched by taking their relay coils to earth - I hadn't realised that.

[Ian Linden]

Thanks for that Ian. Good point about it working without the lights.
How do you post a photo on here? I click Img and get the start and stop markers for an image but can't see how to point to one. I vaguely remember you have to load it into the gallery but I couldn't do that either!

Yes, it's not exactly intuitive.
1 Click Gallery in the links at top-right
2 Click Members Photos
3 Enter an Imagename of your choice, then, below the Image Description text input panel, click Choose File and navigate to the file you wish to upload, then click that.
4 Now click Back in your browser (so back to Members Photos) and find your image. Right-click the image and choose Copy Image Link
5 Now go to the post you want to post, and paste the link between the [img]and[/img]. That's it.

[Ian Linden]

So the headlights are switched by taking their relay coils to earth - I hadn't realised that.

Yes, it's a Japanese practice to control the lights by switching at the earth side. As the Americans say. the lamp filaments are always hot (i.e. have +ve applied, not the temperature!). Can be really puzzling when chasing faults, to find the pos and neg leads of the lamp are at +12V when the switch is to off! If the lights are relay-switched, they follow the same practice.

[Collette Dobson]

Testing my photo insertion skills!

[Collette Dobson]

...............which failed

[Collette Dobson]

Looking at the headlight wiring it looks like on DIP the main current load is going through the relay but that when you put on the BEAM the main current flows to earth through the column switch - which is usually best avoided, especially on older cars with rare parts. Have I got that right?

[Ian Linden]

...............which failed

Sorry, I should have said Copy Image Link, not Copy Link. I have edited your link accordingly, and it works. I will now edit my instructions, to avoid confusion.

[Ian Linden]

Looking at the headlight wiring it looks like on DIP the main current load is going through the relay but that when you put on the BEAM the main current flows to earth through the column switch - which is usually best avoided, especially on older cars with rare parts. Have I got that right?

Yes, the Lo beams go through the relay when the switch is to Hi or Pass (aka flash), but Lo beam goes thru column switch when switch is to Lo, and Hi beam always goes through column switch. See the Service Manual Page 8-17-1 for UK car circuits, and 8-17 for JDM.

I daresay one could come up with a scheme to modify that, but it could prove complex, as you have to cater for the Dim-Dip unit in the UK model.

[Ian Linden]

I think you would need two new relays to achieve the headlamps being relay-supplied. The redesign would involve a fair amount of rewiring.

The design has other imperfections - the action of the headlamp relay to illuminate Lo beams when Hi or Pass is selected will not work for the RH Lo if the left fuse blows, and the Hi beam indicator will not work for the LH Hi if the right fuse blows. Those could be eliminated with the redesign to add the two new relays.