Brian Gaff (Sofa) wrote

That could be done by a chip called a window comparator, witch is capable
of monitoring the current or resistance depending on how its set up, of
each light, but do people really go to this complexity these days?

Nope, these days the system can work out if any bulb has failed.

Harry Bloomfield; "Esq." wrote in message
...
After serious thinking williamwright wrote :
I don't know but mine has the same thing except it sounds a buzzer.

My fancy system indicates nothing at all if everything is working
properly - I'm not sure it is entirely legal to the letter of the law.

Rather it monitors all of the trailer lighting constantly and puts an
icon up on the screen, indicating which bulb has failed. Once on, it
stays on screen, until the engine is restarted - so no chance of it
missing an intermitant problem.