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MG MGB Technical - mgbgt ignition wiring

bought a 72 gt as a project and am having wiring trouble, got a lucas ignition to replace missing ignition steering lock but which wire where? have an owners manual and put white to double terminal and followed diagram but nothing. have changed all fuses and 2 in line fuses and am at a loss. any helpers out there!
j killip

These diagrams may be of some help. Go to pages 12-16 to view wiring diagrams 11-15. These cover 71-72 and 72-73 model years

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

Forget the fuses, the ignition doesn't relay on them. There are wiring to terminal number diagrams here http://www.mgb-stuff.org.uk/isw.htm but that is only of help if your switch has numbers and they are the same as the ones in the diagrams. Failing that you will have to check the continuity between each contact and the others and draw up a chart. Fortunately a UK (I assume) 72 only has four terminals so it shouldn't be difficult.

The switch should have four positions Off, Accessories, Ignition and Crank.

When Off all terminals should be isolated.

In Accessories two terminals should be connected together and the other two isolated. The two connected ones will have Brown and White/Green wires, eventually, call these A and B.

In Ignition one of the previously isolated terminals should be connected to A and B making three connected together, White goes on this terminal. White/Red goes on the remaining terminal that hasn't been connected to anything so far.

In Crank, one of A and B will now be isolated, this has White/Green on it, and Brown goes to the other. Now Brown, White and White/Red should all be connected together and White/Green isolated.
PaulH Solihull

This thread was discussed between 06/11/2010 and 07/11/2010

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