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Electrical guru question

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Electrical guru question
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  This topic is about my 1973 MG MGB
mansep2 Avatar
mansep2 Paul Mansell
Nanaimo, BC, Canada   CAN
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I have changed my entire dash board/gauges and I am using a whole new set of switches (not MG - yes I know for you purists out there.......) however I was sick and tired of the hazard switch breaking any time I tried to use it, so I have replaced the switches with the same as you find in the Caterham super seven, plus I have re located them down on to the center consol. Now the headlight, fan, and hazard switch were easy, in fact the original hazard plug fits the new switch without having to make any changes.

However I also got a brake test switch however the new switch only has two terminals (plus a spade connection for the warning light) where as the MG one has four terminals, so I am trying to decide how to wire this up and every time I think about it my head hurts as I am not the most proficient at electrical circuits.

So anyone out there that can suggest the correct way to deal with this I would be most grateful. I am adding a photo of the MG switch wiring to help.



1973 MGB, restoration while maintaining drivability

I own an MG............Lots of fun and frustration........Just can't beat it.


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rntanner Avatar
rntanner Roger N. Tanner (Disabled)
Oxnard, CA, USA   USA
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1970 MG MGB
1977 MG MGB
Bring up this "very detailed" complete set of MGB electrical diagrams:

http://www.advanceautowire.com/mgb.pdf

Print the Sheets 14 through to 17 in full color.

The real fun/difficulty is that the manufacturer changed the electrical systems several times in the early years

The lower right corner shows the 1973 year model(s).

Sheet 15 is the first with the HAZARD SWTICH Flasher/ HAZARD SWITCH/TURN SIGNAL option

Sheet 16 & !7 are more HAZARD SWITCH, TURN SIGNAL options.



Roger N. Tanner
Professional Engineer, Retired

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gofastandfalldown Avatar
gofastandfalldown Glen Horne
Edmonton, AB, Canada   CAN
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1970 MG MGB MkII "Miss Pandora Moneypit"
Not too difficult at all.

There will be those who will come along shortly and preach about how you don't need the brake test switch, etc. So ignore them. eye rolling smiley

If I'm reading the photos correctly. you have the red and black wires daisy-chained across all of the indicator lamps. If you want to have a brake warning light, then you'll have to wire that one separately. Look closely at the switch symbol in the Advance wiring diagram. You'll see that it really consists of a switch and lamp. Just connect your switch and lamp as separate instruments, just like in the diagram.

Also, your brake test switch should be a "momentary" spring-loaded switch.



Edited 1 time(s). Last edit at 2017-04-30 11:54 PM by gofastandfalldown.

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29desoto Avatar
29desoto Gold Member M Wayne Sanders
Otis, OR, USA   USA
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1965 MG MGB V6 Conversion "Carmine"
1973 MG MGB GT "Eliza - FIRST PLACE - MG2013"
1984 Chevrolet Corvette "The Green Weenie"
1994 Chevrolet S10 "Lil Red"
No idea as to the answer to your question. But nice work, Paul! Looks gorgeous and that's just the back!



Wayne Sanders
Rose Lodge, OR
(TD 4288)

"I don't care to belong to any club that accepts people like me"-joined Willamette Valley Club in 2011

79/65 MGB - Carmine- V-6 - T-5

This car is now very nearly completely done. Sure to find something else, but not now.........And 12 years later, I'm starting to fix things that were new when we built the car. It's pretty well de-bugged!

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mansep2 Avatar
mansep2 Paul Mansell
Nanaimo, BC, Canada   CAN
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In reply to # 3501355 by gofastandfalldown Not too difficult at all.

There will be those who will come along shortly and preach about how you don't need the brake test switch, etc. So ignore them. eye rolling smiley

If I'm reading the photos correctly. you have the red and black wires daisy-chained across all of the indicator lamps. If you want to have a brake warning light, then you'll have to wire that one separately. Look closely at the switch symbol in the Advance wiring diagram. You'll see that it really consists of a switch and lamp. Just connect your switch and lamp as separate instruments, just like in the diagram.

Also, your brake test switch should be a "momentary" spring-loaded switch.

You are absolutely correct after spending half the night thinking about it I came to the same conclusion. I will change the way I have the daisy chain done and wire the light the same as the original switch. It was simple once I realized that I had to seperate that las light from the dash lights.

Thanks



1973 MGB, restoration while maintaining drivability

I own an MG............Lots of fun and frustration........Just can't beat it.

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