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MG MGA - Dimmer switch fastening

I have a missing fastener intended to secure the lower plate of the LHD dimmer switch assembly to its bracket. As far as I can make out, it uses a spring washer, LWZ203, which corresponds to a #10 zinc washer. The screw, as best as I can tell from the Service Parts List (Electrical, p. N3), is given as AJD1243Z, which doesn't correspond to any screw that I can identify from BMC documents. On the other hand,the MGA Nuts and Bolts listing gives PMZ0308 (a pan head 3/16" UNF 1/2" screw) for "dipper switch bracket to bulkhead." Does this latter sound about right? Just when I think I'm beginnng to master the BMC fastener codes I encounter something like this. Many thanks.

Cheers,
Ken
Ken Korey

That is about right
dominic clancy

Ken, I am about to mount my dimmer switch too. Is there a picture of wire attachments by color available?
Harley
Harley Johansen

Thanks, Dominic, for the confirmation.

Harley, my dipper switch is actually wired in (only not well secured to the bulkhead), but the wiring assignments to its three terminals are as follows:

blue with red: to the "dip" or low-beam terminal

blue with white: to the "main-" or high-beam terminal
blue: to dash panel main-beam warning light

blue: from the lighting switch

Unfortunately I can't see my terminal numbers or I could offer a better description of the wires' locations on the terminals themselves. I'll keep looking.

Best,
Ken
Ken Korey

Harley,

Tom Custer seems to have answered your question 12 years ago: http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=6&subjectar=6&thread=2000100301204112665 .

Art Dillelo came up with a more precise answer the year before, one that takes advantage of the "arrow" index for the hot side of the switch: http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=61541571400012&mode=archiveth&subject=early/6&subjectar=6&thread=E199908110027470 .

Cheers!
Ken
Ken Korey

Or you can check a wiring diagram and confirm the correct wiring and terminal numbers, it's as easy as painting by numbers......
dominic clancy

Ah, you could just that if the terminals were numbered, Dominic. As far as I can see, mine are not--and neither are those of others on the threads I cite. The index on the hot terminal, the input from the lighting switch, is a small arrow moulded onto the case. Maybe other Lucas models had numbered terminals.

Ken
Ken Korey

Use a test light or ohm meter to determine which two terminals are electrically common, and which one is not connected. Click the switch once and check again. The one terminal that is always connected to one of the others is the input terminal and will get the solid blue wire.

As it turns out, the center terminal is the input, and the other two don't care which is which.
Barney Gaylord

This thread was discussed between 11/04/2012 and 13/04/2012

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