QuestionGreetings, I have very much appreciated many of the answers I have read here. I have had my 1979 MGB for about 10 years now and have recently pulled it out of a poor storage situation. I am trying to get her back on the road but have not done much, if any work on here in the past. I had an amazing Mechanic down in California and never had the courage to dive in (as I have never been much for fixing cars). My regular mechanic had not been available to me for a period of time and I had a problem that was unfortunately handled terribly by another mechanic. My heater valve was leaking onto my Dist Cap, and he could not figure that out and consequently my entire electrical system was messed with, replaced and in general ravaged ($1,700 for a $5.00 part../cry ). I just wanted to give some history as I may have more questions in the future :) Now the current problem.
My MG had started running poorly and I did not have to time to work on it so I covered her and left her for a couple years. I have been tinkering now and gotten her running again, But I had to buy a new Headlight Dimmer Switch and I foolishly did not check to see if the headlights were working prior to putting the new one in, and so I have no idea if it was a problem that occurred during storage (mouse maybe) or something I did).
I got the new one installed and fresh headlights in and once getting it all set up. Nada. All other lights are working, Turn signals, etc, but neither the brights not regulars have anything.
I am a rookie at wiring diagrams and looking at my Hayes Manual makes my brain hurt. I cannot figure out where some wires go etc, and the layout location of some of the things do not see to make sense to me (like the battery in the diagram appears to be located in the front of the vehicle). Is there some sort of simple diagram that a newbie can use or am I stuck just trying to decipher the Hayes one? Also, what are some possible reasons Both headlights would not be working while everything else is? I greatly appreciate any help in advance and have learned a lot already reading other questions. I know some of these questions must seem very basic, but as someone just trying to get not working on their own MG I just lack some basic knowledge (like how to use a tester to check and see if something has power ) and am trying to figure it all out.
AnswerHi Bob,
Since you have lost both beams you need to take a 12v test light ground the clip and use the probe to test the brown wire on the light switch to see if it is powered. Turn the light switch on and test the blue wire to see if the switch works and if it does go to the dimmer switch on the column and test the blue wire there to see if the power is getting there. If it is, alternately operate the high/low beam switch and test the blue w/white and blue w/red wires at the switch and follow the current on the diagram to the head lights.
A wiring diagram is nothing but a road map so when anything fails test only one circuit by either starting at the source and test each step to the end (the item operated) or some start at the item and work their way back to the source.
Lucas in any British car use blue as a headlight circuit. Browns are always power wires and blacks are always grounds, greens are accessories, whites are always ignition, purple are unfused power wires for some accessory, reds are small lights.
let me know,
Howard
