Hover over a wire to confirm the colour
Tell-tales: Mk1 cars use a bulb holder with two connections as the bulbs are connected between the indicator switch and a special terminal on the indicator flasher, the same as for the ignition warning light. This takes an MES E10 screw-type bulb. Below you can see the 'claw' is insulated from the rest of the bulb holder by a white insulator: (Moss Europe)
Mk2 tin dash CB (not V8) use a standard one-wire instrument light bulb holder (as here) pushed into a metal bracket, picking up an earth from its physical mounting. In front of both types there is a brown 'cardboard' tube that concentrates the light onto the back of the green 'lens' behind the arrow-shaped cut-out in the dash panel. There is a wider black tube at the end of the brown one, the green disc is not visible, encompassed by the black tube. The screws securing the bracket to the dash are behind the plastic moulding round the speedo and tach:
Image from Moss catalogue showing the combined bracket AHH6275 (51, central hole is for the rheostat), 'cardboard' tube AHH6333 (52), green 'lens' AHH6334 (53, the only part shown in the Leyland Parts Catalogue), and 'shield' AHH6332 (54) with a flared end:
This from Andy Jennings shows everything except the green 'lens' disc, including the black shield with the flared end.
My 73 has a straight black tube - without the flare - at the dash end of each of the brown tubes. When I removed my dash 30 years ago I distinctly remember the lens being stuck to the back of the dash with a bit of sticky tape, that was way past its dump-by date. I may have glued them back in as there is no tape visible, but it begs the question as to why the tape was there. One would imagine that the tube and shield support the lens in some way, keeping it pressed against the cut-out in the dash. But that doesn't seem to be the case with mine as sometime in the last 30 years one of my lenses has moved a bit and there is light showing at one edge. That can stay until the dash has to come out for other reasons, although it might be possible to get the bracket etc. out just by removing the tach and speedo ... and rheostat ...
Another view of a Mk2 CB tin-dash car, tach removed:
Early padded dash have a unique lens with arrow fitted from the front ,,,
... and it looks like a metal tube to accept the claw-fitting bulb holder is screwed onto it from the back. The Leyland Parts Catalogue lists this as BHA5124 but shows the V8 version as below, Moss Motors shows the correct item as 142-260: (Image from Betaset)
1970 padded-dash with 2-wire (green/white for this right-hand and black) claw type holder that takes an MES E10 screw-fitting 2.2w bulb. This has a brown insulator between the claw and the holder - not needed in this application but no point in making a 'special' 2-wire unit: (Bill Etter)
Padded dash, all V8, RB 4-cylinder - lens carrier BHA5124 pushes into the front of the binnacle panel:
As originally fitted they are held in place with retaining washer BHA5125 which makes them difficult to remove with the dash in-situ, however the bulb and bulb-holder (13H1925 bayonet, 13H1926 push-in) just push in to the plastic lens carrier, which is plastic so the bulb holder needs two wires, the additional one for the earth. This is the main-beam warning light which is the same:
This is the ignition warning light, indicators and main beam are the same except for the wire colours:
They take a BA7S (GLB281) bulb i.e. bayonet fitting. However unlike bayonet bulbs with pins they do not push, twist and lock, if you turn them through more than 90 degrees they come out again:
V8 and RB main-beam are difficult to get at as access is restricted, RB and early V8 particularly so as the centre console is in the way. For 77 and later with the plastic dash the main beam and right-hand indicator are actually the easiest as the tach is relatively easy to remove. These dashboards have their own sub-harness so were fully assembled on the bench, the sub-harness being plugged into the main harness when the dash was fitted to the car.
The original arrangement is NLA, current replacements don't have the arrow. At least two types - SPB355 on the left, AAU4824 on the right being closer to the original:
You can prize the bulb holder out of the back to replace the bulb and keep the original appearance. These bulb holders have two connections as they are mounted in a plastic panel hence need a wired earth: (Datch.fr)
Ignition and main-beam tell-tales are basically the same.