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MG Midget and Sprite Technical - Have I melted my main beam switch?

Hi all

during last nights driving about, the main beams went out. Alarming, but not a disaster, as the dipped and flash still works. If I try and put the mains on by pushing away from me on the switch it turns everything off apart from the sides, and there's no blip on the ammeter.

Has the main beam switch melted itself?

even if it hasn't and it's something else I think i'll be relaying the switch, and the dipped beam switch as well.

have just fitted halogens last weekend - maybe the last straw? I have extra lights fitted but they're relayed.

any thoughts?

cheers
Rob Armstrong

Sounds like the column switch needs cleaning or is broken

>>put the mains on by pushing away from me on the switch it turns everything off apart from the sides<< that's correxct as it's switching from dip to full

If the wiring and connections are in good condition and you're not adding massive loads then you don't need relays - our cars didn't have relays, my two Spridgets have survived well without them

but if you want to add them and feel happier doing so or your wiring is old or suspect then it's a good idea

I got halogen headlamps last year, recent (but possibly 10 years old) wiring and a possibly suspect column switch without relays on the car (except the one that came with the new electric cooling fan) and all my lights are fine
Nigel Atkins

Rob,
If you look at the size of the contacts inside the column stalk switch you wills see that they are very small. The original Lucas ones seemed to be OK and as Nigel points out were probably perfectly adequate for standard lights.

But the aftermarket ones are poor quality copies and if yours is one of those then for it to burn out is about par for the course. The solution is to wire in relays so that the column switch is only operating to carry the relay current, and not the full load of your headlights and anything else like spots that you have attached. As a bonus you can wire in with decent capacity cable direct via the relays to the lights and will get less voltage drop and brighter lights.
Guy

Halogen doesn't NEED relays - but they do help!
rachmacb

Good point by Guy I forgot to allow for modern made column switches

I shouldn't have forgot as my previous car had a modern made column switch and it used to smoke and smell very worringly and had to be stripped downed to be sorted and cleaned

Some people (not those who suggest so on here) wiring in relays slightly worries me as the quality of their work makes me think they might be introducing more problems than solving

As I said my present, and IIRC previous, Spridgets had halogen headlights without relays and work(ed) fine but I had good wiring and connectors

I'm sure a day will come when I put relays on to my headlights too
Nigel Atkins

do keep in mind that the original fitted headlamps were 35/45W (dip/main)

modern bulbs are often 55/65W, something like 40% increase power going through the switch

on top of that, the aftermarket switch available is probably not as good as an origina, what with the lead being eliminated from solder, and other "modern" touches

as a result, a relay is your headlight switch's best friend


Norm
Norm Kerr

thanks everyone :)

I'll take it apart and look at it later - it may well be a repro one - no idea.

I'd agree with relays adding more complexity and more potential issues - so I'll avoid it if I can, though after wiring the K in a couple of relays should prove no problem.

cheers :)
Rob Armstrong

Norm's figures don't tally with my memory

Rob and my car would have started out with sealed beams of 60/45w (or 60/50w) and the halogen are 60/55w so not a big increase in load

plus our cars have the later design column switch and four fuse box

with the headlight flasher in use wouldn't the load through the column switch be at least (60w + 45w) x 2, 210w for the short time it's used on our cars as standard

certainly with old wiring and connectors and/or a poorly made modern column switch then the UK cars need a relay

with good wiring and connectors plus a column switch in good condition the UK cars don't need a headlight relay unless additional lights are to be added

of course I could be wrong and tempting fate now and will probably have problems with my headlights, very distinctive smell to electrical burning
Nigel Atkins

This thread was discussed between 04/04/2011 and 05/04/2011

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