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MG Car Repair/No power to brake light switch


Hi Howard, my 73B does not have live current flowing to the brake switch nor to the brake pressure switch. I have tried to trace the problem but since I am asking you I have had no luck. The Haynes manual has no information useful to me, can you identify where the power source is located leading to the switches. Any help would be most helpful. Thank you .

Hi Andre,

The brake light switch is powered by the green wire directly from the fuse box. The brake differential warning light switch is also powered directly from the fuse box but a different fuse. There are several green wires on the fuse box and most are on one fuse. The same is true for the brake differential warning switch except the wires are purple and on a different fuse.

It is a common failure for the spring clips on the fuses to get corroded and not make good contact so you should remove the fuses first and clean the spring clips with Emory paper or such.

If that don't correct the problem you are going to need to trace the power from the fluse box down the green wire to the brake switch and the purple wire the same way.


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Howard M. Fitzcharles III


MG from 1956 (USA versions only) up and Engine theory.


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Associate member SAE EAA member

Import Car magazine

ASE Master Auto with L-1 certification up to 2000

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