QuestionI recently purchased a 1974 MGB GT in good condition. Everything works except my brake lights (which apparently worked when I purchased the car). I checked all of the fuses (as I don't know which fuse goes to the Brake Lights) and they all appear to be intact. Is there a straight-forward way to identify the problem? Thank You!
AnswerHi Robert. The brake lights are wired from fuse #3 (green wires one side, white the other side). This fuse also powers other circuits such as the heater fan and the wipers, so if they are working, it isn't the fuse. The fact that both brake lights have failed rules out the bulbs.
You will have to trace the fault as follows:
The 74 MGBGT brake light switch is operated by pressure in the brake pipes. Look for a connector near the fuse box with a switch screwed into it. If you turn the ignition on and put a short piece of wire across the switch terminals, that will tell you if the switch is faulty. Also, check that the green wire to the switch has 12 volts going to it. If not, trace the green wire back to a multi-way bullet connector.
Also coming from the switch, a Green wire with a purple stripe goes to a bullet connector near the heater. This may be corroded or perhaps a bullet has popped out.
In the boot, look for the other end of the same wire, same colours. There is usually a 4-way bullet connector with 3 wires going into it. This may have been disturbed.
