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

Sorry to read of your headlight issue, though in truth it is unlikely to be too difficult to resolve using a bit of logic. Yeah, modernday expectations of vehicle build quality and reliability are perhaps best not applied to 25 year old hand-built cars, sorry.

As for your fault it is almost certainly caused by a loose or dirty connection causing a RESISTANCE to the flow of electricity at that specific point, the resistance will convert the electricity to heat at that same point which will rob the light of volts when it is switched on. Thus the light will fail to illuminate as the voltage across it`s terminals will have dropped due to the aforementioned heat build up at the location of the bad connection.

I do not know the circuit on your particular Morgan, but some have a dim/dip arrangement as opposed to the standard high and low beam direct switching. If yours is the standard switching set-up then you are looking for that simple bad connection, and using the wiring colour code you can pick out the likely points in the circuit where a poor connection might exist.

Blue with a white tracer is the main beam circuit, and blue with a red tracer is the dip beam.

Any and every connection in the circuit has potential to be loose, dirty or just corroded, it is just a matter of finding out where that bad connection might exist, and as has been suggested the fuse holder or fuse it`s self has been found to cause issues in the past on other Morgans. I suspect there may be other connectors under the wings of the bullet type which may have suffered water ingress and subsequent corrosion...?

All connections need to be clean and tight and if left switched on when dirty/loose, the heat will build up will exacerbate the situation.

For wiring diagrams if you visit GoMoG.com, pretty sure you will find some diagrams and descriptions there, but beware that they may best be used as a guide as opposed to "as fitted" in your car, Morgans can vary to some degree even in the same model year and may also be modified by their owners over the years.

Good luck, you will find that folk here are happy to stick with you until you get it fixed.

Worth noting George there is an embellishment of the generic headlamp cable colour codes you mention and particularly relevant, as I believe in this case where headlamp circuits are fused individually according to side and dip/main.

R/H main, blue/white
R/H dip, blue/red
L/H main, blue/slate
L/H dip, blue/pink

So in the OP's case it's the circuit with blue/slate cable he needs to be looking at.

Also worth mentioning to Thomas that any voltage measured at headlamp end of cable should be with bulb in circuit. Open circuit voltages measured by (high impedance) meter will likely not reflect the severity of corrosion resistance limiting current. If you measured 8 volts without bulb I can guarantee it would be a lot less with bulb present in circuit. Note my earlier comments that although fuse may be intact it could still have corroded contacts.

Yep, so if there are separate fuses then I'd guess that's where the feed splits left and right, just before the fuses. On my much older (1986) car there's only one fuse and the feed splits immediately afterwards on the downstream exit from the fusebox.

I'm pretty sure it's going to be a corroded connector somewhere, and my favourite place to look would be where the wiring is exposed the most to road dirt and water ingress.

My fuses are up on the top of the bulkhead under the bonnet and are reasonably well protected, so if it were my car I'd start by looking under the wing in the region of the front suspension as it's pretty exposed to spray there. Then I'd pull the headlamp bowl out of the wing and having a look in there as it's likely to not have been disturbed and might have been leaking for a long time.

If OTOH your fusebox and relays are up under the dash I'd start there, as Morgans are prone to having water leaks under the scuttle and you can get a fair bit of corrosion if the car has been driven regularly in poor weather.

Fuse box diagram here
Wiring diagram here

Useful pic of fusebox John. That would make it fuse 6 as the errant circuit. Although a good starting point for tracing connection issues it's likely to be a connector under the left hand wing where the short loom from headlamp joins the main one, as this area is open to elements and therefore corrosion. Removing wheel will make tracing cable much easier.

Hi thomaslea1, I had problems with one headlamp which turned out to be due to a faulty dimdip relay. In the 1980's cars often had dimdip where changing from full beam to dipped headlights was achieved by passing 12 volts through both headlamps in series, therefore running both headlamps on 6 volts each. Morgan achieved this by using a relay behind the dashboard. This relay is now unavailable, it has nothing written on it and is sealed with resin so can not be repaired.

There are instructions on the internet on how to remove the old relay and repair the wiring. If you feel the small sidelights on top of the wings are inadequate you can change the headlamp bowl to the ones with a sidelight included and couple them up to the sidelight feed at the same time. I have the wiring instructions for removing the relay if you are unable to locate them.

Thanks for the heads-up on the wiring colour changes re individually fused headlamp circuits Richard, seems I am more out of touch than I thought...

Apologies if I added to your confusion Thomas, but you will get this sorted without too much trouble.

Calypso Red thanks for providing the description of the dim/dip unit, I have oft times read of it but never knew how it functioned.

SOLVED: Thanks a lot for all the input. I attacked the fuse panel this afternoon. The panel reference from JohnV6 was close to what I have. That coupled with the wiring diagram really helped.
Pulled each one of the fuses, and found pretty significant oxidation on a lot of the blades. Even tho they tested good, I replaced them with new and coated the blades with a thin coat of silicon dielectric grease.
Lo and behold everything started working again.

Thanks a lot for the input and suggestions.

Tom

Well done Tom, you are obviously made of the right stuff to be a fully fledged Morganeer....

Well done. Clearly you own a Morgan given the comment "The panel reference from JohnV6 was close to what I have"