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MG MGB Technical - Funny headlights

Came home late one night last week and been puzzling over something. I approached my garage door and flashed my highbeams at the door to see the alignment. Something looked askew. My right beam seemed to go from high beam to low instead of low to high, while the left beam went from low to high as it should. I traced my wires back to the valence where the bullet connectors are but all seems as it should. The wire colors are matched. Any ideas? How can I be sure that I'm driving with both low beams and not one low and one high?

Oh, its a '69 roadster and both lights were replaced during a rebuild a year ago. The original sealed beams were replaced with sealed halogens.

Thanks for any replys. Oh, and if Paul H. is around I could use a guru right about now.

Luis
Luis Azan

Though it did not happen to me on my B, it surely happened to me on a GM truck. Seems the guy at the factory put the incorrect wire into the plug in connector at the headlight. So when it was traced out the colors matched at the connectors, but was on the wrong pins at the headlight.
I think I'd try swapping the two wires at the connectors in the harness and see what happens. If both sides brighten and they both dim like they should, chalk it up to a dyslexic in the wiring shop at Abingdon!
Mark Thomas

Is this the first time you have ever noticed this, Luis?

Normally, if you "flash" your brights by pulling back towards yourself on the stalk, all four filaments are supposed to light up {the two high beam AND the two low beam filaments}. What you may be seeing is that one of those four is dead, probably one of the high beam filaments since we tend to use them so seldom.

Many folks don't realize that the headlamp flashing facility on Euro cars were set up this way. In the good old days in Europe (and even here, for that matter) the extra bright beams were used to signal slower traffic to move over to the slower lanes. Or to wake up inattentive drivers.
Bob Muenchausen

Luis - seeing as how the headlights have been replaced 'recently', and the wire colours match, I would follow up Mark's advice, also check orientation (is it upside down?) and adjustment. By bobbing up and down and squinting at the lights you should be able to tell when each is on dip and when on dip by where your eye is in relation to the centre-line of the headlight when you get maximum glare from the reflector.

I'm sure Bob meant what I am about to say. The headlamp flasher only lights the high beams, but if the low beams are already on then all four filaments will indeed be powered during flashing.

The flashing of headlights in the UK could mean one of two things when performed by two cars intending to use the same bit of road - "after you" or "I'm coming through". Two of the former was no problem, two of the latter... Which is why the official advice is that they are no more than a visual indication of presence, same as the horn being an audible indication of presence. The official line on use of the horn went on to say, much to the amusement of my son when he was learning to drive, "It is not to be used as a rebuke". Probably the most ignored piece of driving etiquette ever.

PaulH.
Paul Hunt

Luis, Paul is right about how the flasher works. I think, like you, I only ever paid attention to this at night when the low beams were already on. Thanks, Paul. I learn something every day.
Bob Muenchausen

Thanks for the reply guys. I can tell that all four filaments are working, it just seems that on the right side the light flashes differently from a brighter light on low beam to a "dimmer" than bright on high. I'll do what Paul suggests and squint to see which filament is on at what time and also check on the position of the wires on the bacl of the bulbs. I can tell that the bulbs or buckets are not upside down though.

If I have time I'll try to work on it on Monday.

Luis
Luis

This thread was discussed between 09/11/2001 and 11/11/2001

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