MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Electrical - headlights, turn signal, map light

Left headlight very dim, right turn signal turns on but doesn't flash and map light comes on when I turn on headlamp switch.

Turn Signal Problem: Replaced the flasher, no change, then checked the bulb (which I should have done first) in the right rear (switched with left one) and it was good. There was a hole in the old flasher unit but still spent a few bucks that weren't necessary.

Will go back through everyone's suggestions this weekend to track it down. My electrical knowledge is pretty elementary so s-p-e-a-k s-l-o-w-l-y and at elementary levels for me.

Related problems which occured later: My left headlamp glows slightly but won't light completely. Could that be ground? Where the heck is the ground for the left headlight?

Also, map light turns on when I turn on the headlight switch. I moved a few things trying to get the wiring harness extension that goes to the console area out of the radio slot where the PO put it and have it come over the crossbar then by the side of the radio. Had to disconnect hazard switch, map light switch, etc. to do that. Labeled everything and put back where I got it....I am pretty sure.

Also, un-did some wire near the headlamp switch so I could move them back over the crossbar behind the dash. That was pretty simple too but nothing has worked right since I did them both so I must have disturbed something.

Will go back and re-check everything this weekend. Any other diagnostic process advice would be helpful. Thanks.
J.T. Bamford

JT,

Lots of stuff there.

Headlights: could be ground or power supply; check the connections on the bulb, clean the terminals.

Since there was a lot of fiddlling with the wires, it sounds like a few are mixed up.

Best I can do for now.
glg gimbut

Hi.

The headlights are wired in parallel, so the left headlamp problem is almost certainly due to a bad connection close to the headlamp itself, assuming that the right headlight is working normally and you haven't moved any wires around at the front of the car.

If it is dim on both main and dipped beams, it probably is a poor earth, which could also explain the indicator problem if the car is a later model.

Don
Don

Re Map light...mine will only come on if headlights turned on..I assumed it was meant to be that way???
F Cunningham

John, did you ever see this MG Electrical Site? http://www.mgb.bc.ca/electrical Also, you should take a look at what Paul Hunt has to say as well at his site - http://www.mgb-stuff.org.uk/ Some of what is at both of these can help you out. Good luck.
Bob Muenchausen

I had a similar problem with a dim left headlight and it turned out to be the ground connector behind the grill. The headlight gounds from each side come into a connector there. Cleaning the corrosion from the lead end and replacing the connector solved the problem.

Good luck!
J Larabee

If the left headlight is dim on both beams it could either be the single ground wire connector on its side or the double on the other, where the 'tail' from the lamp joins the main loom. If only one beam it will be the appropriate hot wire in the same places. The eventual connection to the body for both headlamps is further back on the left-hand inner wing and would affect both lamps and both beams equally.

Apart from the final year when both maplight and courtesy light may have been used and both were always available, the maplight is shown on all my Workshop Manual diagrams as being available with the main lighting switch in its first position i.e. off the red or red/green wire.
Paul Hunt

This thread was discussed between 04/04/2003 and 09/04/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.