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 - Fog lights not working and smell

I took the B out last weekend for thr first time in 2 months just to stop it getting too stiff before MGB session starts. Everything was workng well apart from the fog lights ( I have front fog lights fotted) When i pressed the fog light button with the headlights on all the lights went dim so i imedatly swiched the fog lights off but there was an electrical smell that hang around for a bout 5 mins. I continued driving another 5 miles or so before going home everything else was working as god intended. What could have caused this fault anyone got anyideas how to rectify it?
Rab

A short to ground between the fog light switch and the lights.

You have wired them incorrectly, or inadvisedly perhaps I should say, but in this case it has acted as an instant warning of a problem enabling you to switch them off before doing too much damage. You are right to have taken a connection from the existing lights for your fog lights, but it should be to operate a relay and not the lights directly. The main and dip switches are already under quite a lot of 'strain' electrically speaking and supplying the current for fog-lights as well could easily cause them to fail, losing all your lights at once, as well as suffer from excessive volt-drops in the wiring and a slight but constant loss of illumination. It is the relay contacts that should power the fog lights, from a brown circuit, but via a fuse (you can get relays with a built-in fuse) so only that fuse blows in the event of the problem you have. You might like to have a look at http://www.mgb-stuff.org.uk/wn_electricsframe.htm and click on 'Lighting' and 'Fog & Spot lights'.

I don't know whether you have them powered from the side-lights or the head-lights, but for me there is little point in additional fog lights if you are being dazzled by reflected glare from headlights, so I have mine wired to come on with sidelights, both front and rear fog lights. Judging by the number of idiots one sees these days driving on side-lights and factory fitted fog-lights in conditions other than fog, snow or spray, which is illegal, this method of connection (as opposed to usage) is current (ho ho) practice and therefore legal.
Paul Hunt

How do I sole the short to ground or will the relay do that?
Rab

This thread was discussed between 22/01/2004 and 23/01/2004

MG MGB Technical index

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