MG Car Repair: turn signals/brake lights, voltage drop test, turn signals

Question
QUESTION: Hi Howard,

On my 1979 MG, all the electrics seem to work with one exception.  When the brakes are applied, the turn signals stop flashing.  With the brakes released (and brake lights off), the turn signals work just fine.  Is this a flasher problem or should I be looking for something else?

ANSWER: Hi Danial,
I would check the grounds at the tail light assembly on both sides. If the grounds are good, look at your wiring diagram to see if wires are plugged in wrong at the tail light assembly. And it doesn't matter if it is an MGB or a MG Midget.
Howard

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QUESTION: After extensive testing with the multimeter, it appears the the voltage drop that occurs when both brake lights are applied is enough to prevent the original Lucas flasher mechanism from operating.  When either of the brake lights is taken out, the blinkers work fine.

Answer
Since you are familiar with the voltage drop test you should look at the wiring diagram and see if both share the same power supply. I am sure they share the same ground so check it too as a voltage drop test must include the ground circuit also. Do a voltage drop test on the ground circuit first to get that out of the way first.
You still didn't tell me if it was a 79 Midget or 79 MGB.
Howard