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 - no panel lights working

I have just brought my first mgb gt 1971 which i truly love but i have a small problem with the instrument lights THEY DONT WORK which is a real pain at night I have changed all the bulbs in the backs of the instruments but nothing i keep turning the little
switch in between the speedo and tacho and i am starting to wonder shoud i change this ? any ideas
thanks
Richard
r henderson

The lights in mine are very dim and turning that little switch makes no difference to mine either. My speedo is also brighter (a bit) than the revcounter. I will be interested to hear ideas on this.
J M Collins

Richard
Your rheostat is probably fried and when you find out the cost of a new one your eyes will water.
Try joining the two wires from that switch and the lights should, um, light.
Dave
Dave Wellings

Thanks dave thats good advice gives me a good starting point
r henderson

The early rehoststs can be cleaned, there's a small contact point that moves over what looks like a spring.

Also, check and clean all goundings in the instument circut, and too, all connections bullet and spade. It's a simple problem that very well be fixable.

Just go through it with a fine toothed comb using a wiring diagram to point the way.

good luck!

glg
glg

all of the dash lights are powered via a red/white tracer wire, this plugs onto the rheostat and receives its power from the red/green tracer wire from the headlamp switch. Make sure you have power at the red/green where it exits the light switch, if not, the switch inside could need repair. If you have power to the rheostat, check to see if you have it where it exits as you turn the knob. If so, check your grounds and then each individual bulb. HTH>
Jake

All the rheostats I have had to replace (and that is one on every car that had one) have been of the printed circuit variety and the failure mode of all these has been an adjustable but very dim glow. This is because the low resistance sections of printed circuit used for the higher brightness levels have burnt out leaving the higher resistance sections for the lower brightness levels, and as such I suppose that gives it fail-safe. With this type the greatest stress is occuring when the rheostat is almost but not quite in the brightest position, and in use it is quite easy for it to slip from maximum brightness to slightly less without one being aware of it.

I would expect the wire-wound type to be more robust and either work normally or not work at all. Even though they cost £30 or so I feel compelled to replace them as I hate things that don't work - even though I have never used them on less than maximum brightness! However the last one I bought was quite a bit cheaper, but although physically it looks exactly the same it operates the other way round.

The red/green feeds the parking lights as well as the dash lamp rheostat so if the parking lights are OK the main lighting switch is OK.
Paul Hunt


Just put a new Lucas rheostat in my '67 BGT. The clue that it was the problem was that when I turned the knob back and forth quickly I'd get a little blip of light from the gauges. I think the 'stat was about $45 from Victoria British.

Rgds,
Aaron
'67 BGT
'76 TR6
Aaron

I might be inclined to bypass the rheostat in future. I replaced one on my roadster when I rebuilt it a couple of years ago and it cost me £40!! I had to replace it because it was missing but bearing in mind that we don't have the need to dim these very poor lights and don't switch them off it is almost there for cosmetic reasons.
Iain MacKintosh

The only useful thing is being able to turn them off and save a little bit of discharge if you have to park with the lights on.
Paul Hunt

Well thanks chaps for all your help on this i start the repair on Wednsday ,ive managed to get hold of a switch from andy jennings who i found in the classified section on this site, for a fiver lets hope it works will update you
cheers
Richard
r henderson

be sure to check the ground near the windshield wiper motor as well. 4-5 wires in a knot screwed to the bulkhead.
J.T. Bamford

This thread was discussed between 16/03/2004 and 22/03/2004

MG MGB Technical index

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