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MG MGA - taillight wiring, which wire where?

I have two questions about wiring the tail lights. Where does each wire go (see image) and how to connect the wires? Do you use one of those soldered type wire tips on each wire and stick it into the round famale openings? I am realizing that the wire harness did not come with the required wire tips for these connections.
Thanks,
HJ


Harley Johansen

The factory method used an extruded brass barrel termination. The stripped wire went thru the barrel and the wires were then fanned out around the outside of the barrel. They were not soldered together. Then this "termination" was inserted to the round openings you mentioned. The bare wires were wedged between the OD of the barrel and the ID of the openings in the lamp base.

That is why they were not on your harness. I'm not sure but you may be able to substitute the soldered-on connection if you can't find the original style. I'm not sure about that though. You may want to test fit one first.

For reliability, I'd recommend using dielectric grease on these terminations as well as the lamp bulb socket itself.
Chuck Schaefer

I will look at the old harness for those connectors, but doubt they are there. Does anyone solder the wire directly to those female openings? But which wire goes where?
Thanks,
Harley
Harley Johansen

Harley,
You could look in your shop manual wiring diagram or go to Barney Gaylord's web site for lovely colored wiring diagrams. However, it appears your harness may not be standard...anyhow, the black wire should be ground. Please check it to verify. This connects to the terminal on the body of the light socket. The red wire could be either brake/turn light or tail light. Put a voltmeter from the red wire to the black wire. Turn on your lights. If you see 12V this is the tailight. If not, test the white wire. Whichever one has 12V with the lights on is the tail light. Connect this to the terminal for the tail light. The bulb will have two filiments. The shorter one is useually the tail light, the longer one is the brake light/signal. Once you get the tail light wired connect the other wire in the brake light/turn signal connector.
Soldering wires to those terminals is not really a good idea, in my opinion. If you don't have any bullet ends you could buy some crimp-on bullets at the hardware store. Normally 14 gage. They likely will fit tightly enough into the terminal connectors.
Good luck,
Gerry
G T Foster

I went out and snapped this photo. It should answer all your questions. I would not solder directly to the terminals on the lamp base. I did see that I used the bullet connectors and soldered the wire to them. It has worked well for me over the last 10 years. It was long enough ago that I couldn't remember how I did it.




Chuck Schaefer

By the way Harley, your PLINTH is mounted upside down.
Chuck Schaefer

Chuck, thanks for noticing. Maybe it will fit better if put right:)
HJ
Harley Johansen

For bulb connections, see here: http://mgaguru.com/mgtech/electric/et107a.htm

The grounding connection is obvious as it connects to the socket shell. If you get the other two wires switched you would have a bright tail light and dim brake light. Easy to swap the wires if you check it and fix it before installing the lens.
Barney Gaylord

This thread was discussed on 04/08/2010

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