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MG MGB Technical - No High Beams

Just started having interesting problem with my 68 MGB.
When I turn on my high beams my lights go out. Also no high beam indicator on the dash. Seems strange for both lights to go out at the same time. I'm figuring a wiring problem or a problem with the turn signal assy. Which is only about a year old.
Anyone had a similar problem? Any suggestions as to where to start would be most appreciated.

Rick
Rick Bartell

I'd get a wiring diagram and start with the headlights and work your way backwards. Figure, there should be two similar color wires to the lights themselves, these will morph into one somewhere in the egine bay, this should connect to the high beam switch, which should be powered by the headlight switch. Just take a multimeter and check for voltage as you go. If you get to a switch, highbeam or lights, and you have power in and nothing coming out, you figure the switch is faulty. The reason I say start with the lights is, if both bulbs are burnt out (rare, but poissible), you'll do all the work with the rest of it to find out. Also, the lucas wire connectors are pretty bad at aging and either coming undone, or corroded to the point of no longer allowing electricity to pass. These are also very easy to test.
John A

Rick,
As John says, "get a wiring diagram". I would then jump between the wires for high beam to elimenate your high beam switch. If they work, you know the problem. If not, start tracing the circuit. There are several connectors (e.g. engine bay, near each horn) you can check, as well as the light bulbs themselves.
Dave
David Steverson

Rick,

i had this problem very recently & it was due to a bad earth. On my car the headlamps are earthed to the inner wing, this connection had some surface rust, i cleaned this up with some emery paper & all was working again.

Also check all the bullet connectors for rust. I cleaned all mine up as a precaution, unfortunately most of these for the lights are at the front of the car & get a hammering, from road salt, water, etc.

Good luck

Scott
Scott Ralph

Rick,

The high beam wiring should be blue/white. Check the connectors just at the sides of the radiator that connect the lighting wires to the main harness (these are the bullet connectors). However, since the blue indicator is not coming on, there may be a connection or switch problem inside the switch assy. You can remove the cowl and check it out. Also, there is an excellent site with wiring diagrams that you can probably find by visiting the archives and searching on electrical.

Cheers, Doug
Doug Keene

Do the lights work on the headlight flasher - if they do then the problem is the switch - buy a new one - they are impossible to repair satisfactorily
Chris Betson

Ive got the same problem - wire broken off the indicator stalk switchgear. I keep soldering it back on but it only lasts about 3 months. Embarising when it fails and you are out in the dark. Mind you no one notices if I drive on dipped or main beam they are both dim.
Paul Hollingworth

Rick:

Here's the link to the wiring diagram.

http://www.mgcars.org.uk/electrical/lighting.html

I'm trying to solve a problem with my headlamps too - so far no luck but I've only made it half way through the circuit.

Good luck.
Boris

Yes I had a problem with the new expensive multiply switch on the steering column. Seams the contact for the highbeam melted. However the highbeam flasher worked when I pulled back the lever. Oh, 1969 BGT.
I have installed relays for headlights and now need to order another stalk mounted highbeam switch assembly. Yikes! Your right can't repair it.
Geoff
Geoff Kimler

If the panel and parking lights stay on it is simply a problem with the dip-switch which disconnects the power to the dipped beams before it connects power to the main beams and tell-tale. If the panel and parking lights are going out as well there is probably a short in the main-beam wiring but a bad connection in the feed to either the main or dip switch, ar in the main switch itself, is 'protecting' your loom against melt-down. As Chris says if the headlight flasher works OK the problem is in the dip-switch.
Paul Hunt

This thread was discussed between 24/02/2003 and 28/02/2003

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