No headlights, or horn, or hazard lights....

[Kiajon]

Afternoon. Whilst getting on with my greasing and oiling (see my other questions) I thought I’d check out the electrics. To be honest I wished I’d kept greasing!

My back end seems fine - so to speak - indicators, brake lights, reversing light all good! The front, not so good! The headlights, side lights don’t work. The headlights will flash main beam but not go on to main beam. I then noticed the horn only worked with the main beam flash!? 
I changed the fuses - didn’t know which was which so I changed them all - but no improvements. I’m trying to get my head around the wiring diagrams - being a bear of very little brain this is challenging - and have a lovely colour version from a different thread. But where should I be looking at on the the car? 
Any clues/starting points would be gratefully received!

Thanks again.

Jonathan

 

 

[Colin Lindsay]

I'm assuming Spitfire? If headlights flash, that shows power is getting through to the circuit, but through the flasher arm, not the main dashboard switch - that's where I'd start, especially if the horn sounds when the lights are flashed. These all operate through the same fuse (brown wire circuit) and are on the same fuse as the hazards and the interior courtesy light.

Check the wiring in behind the fusebox and dash, but especially round the steering column; I suspect a short that's allowing power through the headlamp flasher but not affecting either the switch or the fuse, and if that's okay suspect the lightswitch itself, although if the tail lights illuminate I still reckon it's a short somewhere. Even wiggling the cables about, especially at joints, can cause the lights to flicker and point to a problem, so have someone keep an eye out or try it at night where you can see the glow from inside the car.

Do the indicators work? (Different fuse circuit but it rules out a bad earth to the sidelights).

 

[NonMember]

OK, first off it's important to know what model we're talking about. Even if it's a Spitfire, late 1500 is different to all the rest!

If it's an earlier one, the horn switch on the wheel is a ground-side switch. The power for the horns is all under the bonnet.

[Kiajon]

Cheers chaps. It’s an 81 Spitfire! 

[Kiajon]

And the indicators work. 

[dougbgt6]

The fuse box is a weak design. The two spigots at either end of the fuse, you’d think they were made out of one piece, they aren’t! You put the fuse in, then they’re connected. Because they’re two pieces they don’t grip well, so you get the fault that two at one end are touching the fuse, but only one at the other. This leads to all sorts of head scratching symptoms.

Take the fuses out clean the holders and pinch them together, this works, for a while! 😊

Doug

[Kiajon]

So I took the centre part of the dash out. When I put a multi metre from the connector with the big brown cable to one of the others on came the headlights! I took the switch out and ran the multi meter across it and no matter which connectors I joined or what position the switch was in the reading was 1! Presume this means the switch is b#ggered?! 

[Colin Lindsay]

Seems to be the switch, alright. They're readily available online or from suppliers. Am I right (I was never a great multimeter user) that it should read zero if the switch is working correctly?

[Kiajon]

28 minutes ago, Colin Lindsay said:

Seems to be the switch, alright. They're readily available online or from suppliers. Am I right (I was never a great multimeter user) that it should read zero if the switch is working correctly?

To be honest I had to read up on multimeter usage! I believe it should be close to zero or zero depending on how good the meter is! NoS switch ordered! I’ll go back to my greasing and brake jobs while I await it’s arrival.

At some point I hope to get the old girl MOTd but that seems a way off! 

[Kiajon]

I found a light switch on a replacement dashboard and having fitted it I now have headlights but still no side lights or hazards. Back to the fuse box? Or something else? 

[Colin Lindsay]

Could still possibly be a dud switch... I'm so used to my earlier cars having the switch on the dashboard but then the functions are controlled through the column stalk, so can't remember how the later cars work - three position switch, first off, middle for sidelights then fully down for headlights? Disconnect the headlights from the switch and connect the sidelights to the headlight terminal to see if they come on.

It could be an earthing problem at the sidelights, run a separate earth and see if anything lights up. Long time since I had a Spitfire (mine was a 1977 model) but I remember problems with the hazards that turned out to be incorrect wiring; with the left hand indicator on I had three that flashed, and with the right hand indicator on it was a different three. 

[Adrian]

Switches can be a pain - I found a replacement hazard switch fixed the hazzards, i believe these are notoriously poor. Having done my car I'd advise you sit down and trace the circuit both on the diagram and the actual car. I had wires that were redundant and others that wern't according to the diagram as it's quite common for PO's to cut corners. I'm no auto electrician but it's well worth making sure of your wiring first as you can't guarentee that it is as per the WSM.

[Kiajon]

This is a fantastic learning curve. slowly learning how to read wiring diagrams. It’s a bit like working out the London Underground system without the social distancing concerns! 
It is a three position switch, off, side, headlights. I’ll switch terminals and see what happens. Not sure how to run a new earth but I’ll read up on that! I have a spare hazard switch (currently running the additional electric fan) and I’ll see if I can change that over with the current hazard switch, once I work out how to take off that part of the dashboard...... might be time to switch that over whilst I’m at it! 

 

 

[dougbgt6]

You’d think the hazard would be a simple switch, on or off, but no! It’s used as a junction point and I think there are 6 connection?

Doug

[Kiajon]

1 hour ago, dougbgt6 said:

You’d think the hazard would be a simple switch, on or off, but no! It’s used as a junction point and I think there are 6 connection?

Doug

Having looked at the wiring diagram I realise that now! This is going to be a bit of a b#gger I think! 

[Kiajon]

Had a rethink and second look (while trying to get to the hazards switch). What isn't working: the front side lights, the hazards, the gauge lights, the rear lights. Brake lights, indicators, headlights, courtesy light, seatbelt light, fuel gauge all work. 

Trying to work out the common link but I realise as it's an old British car there is likely to be very little logical about it!

Cup of coffee and head scratch required!

[Kiajon]

I keep coming back to the fuse/fuse box. How can I check it and cancel it out of the equation once and for all? 

[dougbgt6]

 

28 minutes ago, Kiajon said:

What isn't working: the front side lights, the hazards, the gauge lights, the rear lights. Brake lights, indicators, headlights, courtesy light, seatbelt light, fuel gauge all work. 

OK here’s the coloured digram, there are errors, the fuses are misnamed, but call them red, purple and green. It’s also for an American Spitfire so there’s stuff that you won’t have.

The Hazard switch is on the green fuse so that’s a separate fault. All the rest of the things You mention working and not working are on the red fuse. Which makes me think one of the “spigots” I mentioned earlier isn’t making contact

[Kiajon]

Took fuses out. Cleaned spiggots popped back in. Nothing. Pushed on spiggots when fuses were in and the middle one moved back about 1mm. I have lights! Doug you are a God amongst men! Thank you. Obviously the fuse box will need an upgrade (I've been looking at previous threads on that and I'm not sure I'm ready!?) but for now the old ones will do as I try and get her ready for an MOT!

Now on to the hazards. 

[NonMember]

As Doug says, all but the hazards are one circuit. If directly bypassing the master light switch doesn't make them come on, it's probably the fuse box (or the fuse itself, of course!)

The hazards are often caused by the switch, which gets little use and corrodes the internal contacts. Operating it several times can sometimes fix that. Alternatively, it may be the flasher unit if it's a separate unit to the indicator one - not shown as such on that diagram, though. I'm more used to the earlier cars, where it was. I think Doug is wrong on one thing, though. The hazard switch has both green and purple connections, which is both of the "other" fuses. The green one is for the indicators, it's the purple that powers the hazards.

[Kiajon]

Dashboard out. Hazard switch removed. Given a good dose of contact cleaner and manipulated lots. Refitted and hay presto we have hazards. Now just to put everything back! You need the hands of a Thai veterinary surgeon to get to some of those fastenings! 

Thanks for all your help again!

[yorkshire_spam]

Hmmm my money would have been on the contacts on the back of fuse 3 (bottom) as it feeds horn, main beam and hazards (brown - always live, purple - fuse always live), you live and learn!

 

[Adrian]

Just keep in mind if the hazard swith is corroded and you've cleaned it up it is unlikely to be a particularly long term fix. But at least you know what to do in the future.

[Kiajon]

47 minutes ago, Adrian said:

Just keep in mind if the hazard swith is corroded and you've cleaned it up it is unlikely to be a particularly long term fix. But at least you know what to do in the future.

Indeed. I will be looking for a replacement. But for now it'll do. My goal is to get her road worthy so I can take her down to my friends garage and have her MOTd. I'll then know if there is anything major that needs sorting. If not then I can run her and start doing some upgrades/longer term fixes.