Shonky headlights!

[willcolumbine]

Okay, following on from the sucessfully concluded 'shonky indicators' thread. I've now got some headlight problems!

My lights failed yesterday, at night, on a remote country road and today I'm having a bit of trouble tracking down the problem. Basically if I press the light switch to the first position I've got sidelights as normal. If I press it to the second position I've got sidelights still, but no headlamps. If I flick the lights stalk by the steering wheel up and down I still have no high or low beam. If I pull it back I get the lights flashing as normal.

Could something in the stalk mechanism be the problem? Also, this has happened after upgrading my headlights to halogen ones. I've got the same wattages as before so that couldn't have made a difference could it?

[ferny]

Iffy switch? I've had similar things on the Herald but the flasher connection on the stalk failed on mine. I was wondering why no-one would move when I flashed them to let them through etc. I just resoldered it.

If you've got the same wattage as before then it should be fine. The amps won't have gone up.

[sparky_spit]

If you have the standard switch for a Mk4/1500 in the centre of the dash, then it's almost 100% certain it's that switch which is at fault. They come apart easily, and you will probably see that it's all black and horrible inside. As long as you take it apart carefully (it just pulls apart) and lay the bits and springs down so that you can reassemble correctly afterwards, it's easy. Clean the insides and contacts with switch cleaner or WD40. If using WD40 you can leave the insides a bit wet to help lubricate the contacts as well (some switch cleaners dry very rapidly and are not always that kind to 1970's plastics). It just clicks back together. As someone else on here just said - "job's a fish" :)

[piman]

Hello Will,

I'm sure S_S is right, but to elaborate, the reason the flash works is because that is a separate feed to the flasher and does not come from the light switch. (Else you could only flash when your lights are on.) Worth remembering if your headlights do go out, just hold the flash on until you can pull up.

Alec

[willcolumbine]

I've had a look at the rocker switch on the dash. It's obviously not that! The continuity is perfect and all there is inside is clean brass and switch lubricant. It's like new!

I guess that means my next suspect is the indicator stalk mechanism. It looks alright but I'll have to try and get it out and look over it. I'm not exactly sure how it works but I guess it'll be obvious when I take it apart. Any common problems to look for?

[Greeks]

Did you upgrade to halogen without fitting relays?

Could be that you burnt the switch out... sounds similar to what happens on the saloon and dolly light switches.

[sparky_spit]

On the light switch stalk, just look for burnt/dirty contacts, wires having fallen off (unlikely), or most likely overheated contacts that have melted the plastics moulding allowing the tension in the contact springs to fail.

Upgrading to same wattage Halogens should not have caused the problem, as they will draw the same current as before, in theory... unless Halogens do draw more current somehow over the equivalent Tungsten lamps. I can't see how though, as it goes against VxA=W theory.

Somebody tell me if I'm talking rubbish?

[neilnaz2]

I got the impression that Will had fitted relays? If not then similar wattage should mean similar current. I think that even if fitting similar wattage halogens relays and new high capacity wires and fuses are a very good idea. The existing wiring may be ion very good nick but is likely to be inferior to decent modern wiring. You use, as others have explained, the existing wiring to drive the relays and new decent gauge wires direct from 12v via the relays to drive the lights.

I remember losing my main light switch in my previous Spitfire on a dark road. It turned out that the rocker switch was getting hot with the current and that was just feeding standard sealed beam units at the time.

If you are considering changing to halogens then you might get away with using the existing wiring but do not use higher capacity bulbs than the sealed beam units as you will be running higher currents through the existing switchgear and wiring.

Best of luck finding what has gone wrong Will............

[willcolumbine]

When I upgraded my headlights I didn't fit relays. I'm using the same wattage bulbs as I had previously so I figured P=IV and the voltage and power are the same so the current should be as well.

Got to admit though it is very strange how it happened the first time I used full beam for a while. Tends to suggest that there has been an increase in current load on the wiring dosen't it?

Whatever, I will get back to the garage and start tracking it down!  :)

[willcolumbine]

After a few minutes with the multi meter I think I may have found the source of my problem. The light stalk switch appears to have a bit of a dodgy connection. There's no sign of burnt or dirty contacts but there's no continuity between the brown wire that brings the power in and the terminal it's attached to. It's pretty wierd actually because the terminal and the eyelet with the wire attached to it appear to be in metal to metal contact. The multi meter dosen't lie though - the powers just not going through!

These switch things look like they might be a bit pricey so I'm thinking a blob of solder might fix it but the terminal is backed by plastic so it might be a bit tricky! :)

[Greeks]

willcolumbine wrote:

When I upgraded my headlights I didn't fit relays. I'm using the same wattage bulbs as I had previously so I figured P=IV and the voltage and power are the same so the current should be as well.

That maybe so, but it's still a good idea to fit the relays. The car I had burned out switches (2 in 24 hours) had standard lights in. It's a good idea regardless, this is Lucas electrics we're talking about here. When I fitted relays to the next car without changing the globes, no other mods it went from this:


To this: