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MG MGA - Light switch failure

While driving home last night, the side and headlights both failed. I managed to trace the problem to a faulty light switch.

I still have the orginal switch, and wondered if anyone has managed to repair or service the light switch?

Regards...John
J Bray

Not sure if this is your case or not. When my 63 MGB light switch was acting up. I tooked it out and sprayed PB Blaster into a small hole in the corner of the light switch box. Let it stand a few minutes and blew it out with my air hose. I did this several times. Never had a problem again. My problem was apparently corrosion, if yours is the same problem. What I did may fix your problem.
Ray Ammeter

Hi John

Yes I have taken apart the light switch and cleaned it up. The shaft running through the centre of the switch has a nut on the end which is soldered on to retain it. I managed to get the nut off with a bit of heat and used thread lock when I put it all together again. Its relatvely simple to take it apart and clean up.

There was a NOS switch on ebay the other week which I think did not sell.

Looking forward to the beer for the seat belt bracket drawings!

John
John Francis

Question for J Bray:
Did the lights work then fail while you were driving?
Or did the lights not come on when the switch was pulled?

I have a replacement switch from Moss Motors (2007 purchase) that on at least two occasions did not connect when pulled. The first time the car was parked on a dark city street, and no lights when the switch was pulled. I fiddled with the switch knob (on-off multiple times) and poked at the wire connections without success. I then drove it some, and when the car hit a bump the lights came on. The second time it happened in my garage before I left home, pull switch and no lights. While poking around the back of the switch I touched the tail end of the switch rod, and the lights came on. I have been able to duplicate this situation a couple of times.

This is not the only quality problem with the Moss replacement switch. See here: http://mgaguru.com/mgtech/electric/et117.htm
I have been looking for a good used switch or new OEM switch. Sorry I missed the eBay sale.

These are gross motion switches. For an older switch with corroded contacts, in may cases simply cycling the switch multiple times will clean the contacts to restore good operation.
Barney Gaylord

Ray/John

Thank you for your observations. I will try unsoldering the end nut and see what the contacts are like inside.

Barney,

The lights failed while I was driving. They worked fine for the first 150 miles of the day and then failed without any warning on the return trip when I went from side to headlights.

I managed to get the lights working by tweaking the wires in the back of the switch, but every time I went from side to headlights they would again go out.

My presumption is an intermittent connection inside the switch and the main brown and blue wire is running hot at the switch end.

It's an original switch and I have the extra fuses on the lighting circuit and these were all fine

Regards...John
J Bray

John,
I'm attaching a photo of a repair my friend use to fix his headlight switch. Loss of connection is not an uncommon problem. Notice the solder joints. This is a way to fix that.
Cheers,
GTF


G T Foster

GTF,

Very interesting, I hadn't considered a loss of contact under the posts but a quick check does show poor continuity at this point.

Regards...John
J Bray

Barney, John look for ebay item Uk 271054588939. It might still be for sale but hasn't been re-listed. It may not be NOS but looks in good nick.

John
John Francis

Not surprised it didn't sell, as a new one is only $5 more. Given a choice, I'd buy the used original one, but the ad says the seller won't ship to USA.
Barney Gaylord

I had all the issues mentioned By Barney when I bought a new switch back in about 2007. I was actually trying to adapt such a switch to operate my windscreen wipers and washers. First pull put on the wipers; second twist and pull the washers. It kept shorting out, resulting in random, sometimes unstoppable water sprays giving me a 'facial' behind the sports windscreen. The switch is now in my junk box.

Steve
Steve Gyles

This thread was discussed between 30/09/2012 and 03/10/2012

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