Evening all.

Sidelights are fine.

Dipped beam, the OS light is visibly dimmer. Swapped bulbs and it's the same. When the main beam is switched on, the OS dims even more. When the main beam is switched off, the OS returns to its visibly dim state BUT, the main beam indicator on the dash stays on (albeit not as bright) and anything using relays triggered by the main beam (roof lights, etc) stay on.

Any suggestions?

earthing or high resistance. Could even be a dodgy steering column switch.

change the headlight plugs for ceramic versions and do the relay mods as in the CFAQ section.

Cheers. I did think the "sticking" main beam might be the column switch. The relay mod looks cool and makes sense, my difficulty would be where I could add four more relays.

auf_wiedersehen_pet said:

Cheers. I did think the "sticking" main beam might be the column switch. The relay mod looks cool and makes sense, my difficulty would be where I could add four more relays.

Click to expand...

Using relays as in the @The Mad Hat Man mod will definitely take the electrical stress off the stalk switches due to the very much lower current required to drive the relay coils than that required to drive the lights directly.
It also has the advantage that a larger gauge of wire can be used to feed the headlamps, therefore reducing the voltage drop across the wiring and remembering that the power feed from the battery to the additional fuse block and relays must also be increased to carry the high current.
The wire between the battery and the fuse block will carry in the case of two standard bulbs of 55 watts together which will draw almost 10 amps (2 x 4.3 amps each) in a pre-facelift Disco; either two main or two dipped lights and almost 20 amps on main beam on a facelift Disco 2 where all four bulbs are illuminated at the same time.
However, the relay mod won't improve headlight performance if any earthing problems at the headlight fittings are not addressed first.
I'm sure that with a bit of thought you can find about six inches on a bulkhead or inner wing to fix a 4-way relay block, one of those which includes the required fuse holders too.

Cheers Brian. If I get chance tomorrow I'll get a photo of the inside of the bonnet - it's tight in there but I'm sure I can squeeze some in.

The good news is I took the headlight bulb out this AM and everything returned to normal. I guess this points to the fault as a wiring fault. Most of the bits I need for the relay upgrade are in my wiring box the garage so I'm probably going to fit the relays inside each of the headlight boxes.

Check carefully the wiring which is common to both filaments down to earth.

Here's the available space.

Pff ..... plenty of room ..... somewhere, just have to look closer!