Have no idea if this might help... a pic of the relays behind the dash on my 1986 +8 Ignore the blue relay which controls auto choke operation, the other two are flasher related and you can perhaps gain understanding by checking the colours of the wires and identifying them from the colour code list in the link below... Perhaps a handy sheet to print out ..?

http://www.mgb-stuff.org.uk/colourcodes.htm

Good luck.

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