Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing one High Beam is out!

I REALLY didn't want t project when I bought this car, but one high beam isn't working either on dip or flash it seemed like a simple bulb replacement.
Well, the bulb is fine. Connected to a separate battery both sides work. Checking voltages I do have battery voltage to the low beam side, but low voltage on the high beam side. Voltages checked on the bulb side of the headlamp connector.
Thoughts?

Oh yeah: 1995 Plus 8, USA spec, driver's side (left) headlamp.

Suppose I could "engineer" it and run it off the right side lamp, but I'd rather do it right!

Have you tried running an earth wire direct from the battery to check for a poor earth?

It might be a fuse. Some cars have sided fuses.

but you bought a Morgan......

James

p.s. hope you get it fixed OK

If you've got <12V on the positive feed to the main beam that's not working, it implies that you have high resistance in the feed. This is probably down to a corroded connector somewhere. I'm not sure of 95 model cars, did they have headlamp relays? If so, then that's where I would start looking, along with the underwing connectors that link the headlamp bowl with the main loom.

And if you don't have relays between switch and bulb, I would strongly advise you fitted some immediately. It's an easy job, and it saves the high current from burning the contacts in the dipswitch. replacement steering stem switchgear isn't cheap.

I believe as John V6 suggests there are separate fuses on your car for high and low beam, left and right, so four in total. For high beam left hand side look for the fuse with a blue/slate cable and check by replacement. If fuse ok, confirm full volts available each side of it. If ok check connectors on blue/slate cable under wing that feed that particular headlamp.

Obvs worth checking, but if a fuse has blown wouldn't OP be measuring 0V rather than low voltage on that feed?

thomas, as others have said it is probably fuse related, I had a similar problem the fuse was not blown so I cleaned the fuse ends with emery (and also the fuse holder) and all was well.

David Byrne

No not if fuse contacts are corroded.

Thanks for all the suggestions.
Both low and high beams use the same earth wire. Only the high beam is affected tho. Low works fine.
There IS voltage present, but low. To me, that would eliminate the fuse as the problem as some voltage (about 8VDC) is present.
If there is a relay I'm pretty sure it would be used for both high beams.

I don't have access to a wiring diagram, but somewhere the left and right high beam feed wire must merge. Anyone know where? Correct power must exist to that point for the right high beam to work correctly.

Is there an on-line wiring diagram available?

Thanks
Tom