Re: Indicator light in speedo problem
Posted: Wed Mar 14, 2012 6:38 pm
ricarbo wrote:Brian, I should like to think I am wrong, because I like LEDs, with their much improved reliability and lower power use. I'm puzzled that you get the right flashing rate using them, as it is supposed to be affected by the load.
But, I think there may be a problem with using them, from a legal standpoint. As I understand the Road Vehicle Lighting Regulations, you are not going to meet the rules. I've had a look on the internet and have copied the following extract:-
11. Tell-tale?(a) One or more indicators on each side of a vehicle to which indicators are fitted shall be so designed and fitted that the driver when in his seat can readily be aware when it is in operation; or(b) The vehicle shall be equipped with an operational tell-tale for front and rear indicators (including any rear indicator on the rearmost of any trailers drawn by the vehicle).12. Other requirements?(a) Every indicator (other than a semaphore arm, that is an indicator in the form of an illuminated sign which when in operation temporarily alters the outline of the vehicle to the extent of at least 150 mm measured horizontally and is visible from both the front and rear of the vehicle) shall when in operation show a light which flashes constantly at the rate of not less than 60 nor more than 120 flashes per minute. However, in the event of a failure, other than a short-circuit of an indicator, any other indicator on the same side of the vehicle or combination of vehicles may continue to flash, but the rate may be less than 60 or more than 120 flashes per minute. Every indicator shall when in operation perform efficiently regardless of the speed of the vehicle.
I understand this to mean the lamp in the speedo will have to work at MOT time and a failure of a lamp has to alter the flashing rate, but I can't see how your arrangement will do this. You could fix the speedo lamp by running it off a relay easily enough,and maybe your audible device might get you over this anyway, but the other part of the rules would be much more difficult to satisfy. I wonder what they do on modern cars with LEDs - presumably a much fancier electronic flasher unit?
Richard,
Perhaps I'm missing something, but as I see it, I comply with all the condition of rule 11 & 12. I know I'm a bit thick, but having read the rules four times, cannot see where I don't comply.
I fitted LEDs primarily for two reasons: 1. to make the system more reliable and reduce the current demand on 40 year old cables (this includes the rear side, stop, reversing and front side lights). 2. IMHO, LEDs give better light saturation than filament bulbs on all the individual lamp optics.
Not unlike Alex, I have always been in the Elan driving seat at MOT time so the issue of any of the dash lights not working has never been a consideration of the test.