MG Electrical Grounds
- Gerry Masterman

As of:  16 April  2006 

        Damned grounds! 

        Ninety percent of the electrical problems on our MG's are from bad ground connections.  Sometime lights work, sometimes they don't.  If you find power at the socket and the bulb is good, then chances are real good that the problem is just a bad ground.  To make things worse, it seems that some of the light fixtures were just designed to fail.  Ever notice how some fixtures have a black ground wire attached to the socket and some don't?  The one's that do not have this wire already are counting on a good mechanical connection between the ground side of the socket and the body part to complete the circuit and could benefit from a bit better connection. 

        Here's what I do:


This is a front turn signal light from my 72BGT.  It had just two wires originally, both hot wires when the lights were on or the turn signal was in use.  There was a rubber insulator between the fixture and the body so in order for things to work, the designers were counting on an electrical ground through the mounting screws or a cast in locating tab.  Neither were consistently good grounds.  So, I drilled a 1/8" hole in the metal case and with a wire connecter and a stainless steel pop rivet, I added a third wire. the third wire has the same Luclar connecter on the other end as the others and can be hooked to the ground wiring harness that goes to the headlights.  After attaching the ground, the whole thing was repainted and the wires were wrapped with tape.  A bit of Vaseline under the connecter will prevent any corrosion from starting for years.

        Along the same lines, you ever installed an instrument in your dash and then realized that your light for that instrument does not work?  Then you remember that damned black wire with the loop connecter that you were supposed to put under the thumbscrew but forgot because you were doing everything you could just to hold the instrument in place, hold the mounting bracket in place as well, get the thumbscrew started without dropping it into the behind the dash bottomless pit of wires and dark places that have not been seen by human eyes in thirty years?  

        Well, here's what I did for the instruments in my car. 

I drill and mount the same ground wire as above to the back of the instrument cans. Now, I have a dedicated ground wire for each instrument that can be hooked up with ease! Just make sure you check for clearance inside the gauge case when you decide where to drill the hole.  Oh, and be sure you remove the gauge from it's can before drilling!