MGB Tail lights do not work- 1977

The tail lights, rear parking and license plate lights on my 1977 MGB work intermittently. The head lights and brake lights work fine. Any idea the problem. I am guessing there is a problem with the lamp switch on the steering housing.

First thing to check ~always~ is ground. If I'm not mistaken, there's a common ground point back there for those lights. Take a look along the back panel and you should find a grouping of black wires. Check that connection - loosen the screw and clean up all contact points and see how that does.

And welcome to the party here!


Mickey

Open your boot. Look straight down and you will see two nuts holding your license plate mount to the body. The drivers side is where the grounds are attached. That "should" be the ground for those lights. I have a 78 B opened up in the garage now. Thats the only reason I could tell you where. Your lucky, tomorrows the day I start to pull all my wiring out. Then I would have had to keep my mouth shut for fear of making a fool out of myself.
Welcome to the BCF! Were looking at moving to portland in about a year for my wife's masters program. How do you like it?

If its the HL switch the parking lights in the front would also not be working. The rear lights have separate wires off the fuse box for each side. I guess it could also be a fuse making contact some times and not other times. If the ground was bad at the license plate the fuel pump gets its ground there. No mention of a non running car. (if the fuel pump and wires are as original) Bob

This is one of those times when "bad grounds" is not just a one-size-fits-all solution to electrical problems. Seems highly likely to me.

This would be a good time to buy a cheap multimeter, or at least a test lamp, and start practicing troubleshooting--trace through the circuit to see where you are losing voltage. Check for voltage at the lamps, and if they have no voltage, continue up the circuit toward the source and see where you are losing it.

By the way, don't assume that the problem isn't simple. Are the bulbs OK? Are the socket contacts clean? Seems unlikely that more than one bulb would die at one time, but coincidences do happen sometimes.

"Practicing" is a good term for it. I feel like I learn some thing new every time I pick that tool up.
muhrich, whats your progress?

Look to the Lucar connectors at the firewall on the passenger side. Specifically the green, green/white and green/red wires.

Green/white right signal, green /red left signal. Green just keyed power. Red circuit for tail lights. Fuse box probably just dirty at the red terminals. Marker lights have a blue wire that plugs into red at the rear of the car.

Also, see if they work when headlights are on, or just don't work at all. That bolt behind the license plate others have mentioned as a ground point - clean up the connectors and the actual part of the body they screw down on. Also possibly the flasher could be bad.