Saturday 10 March 2018

Brake Lights

Just had a very interesting day.    On my last run I noticed the brake lights had stopped working again.   So I checked the circuit and the switch and found everything was OK.   There was 12V on one of the switch terminals and the other terminal connected to the lights.  

But when I bridged the switch nothing happened.   But, when I put a direct 12V to the lights terminal as a test. everything lit up.
So it seems that although there is a 12V supply on one switch terminal when measured with a meter, once you close the switch and put the load of the lights on the circuit there isn't enough current flow to illuminate the lights.    So I can only assume that there is some resistance in the live wire circuit.

Now, a 'real' mechanic would have spent hours tracing the circuit back to try and find the problem.    I spent 10 mins wiring in an alternative 'jump' supply from the ignition-live circuit to the switch.  I even included an in-line fuse.

Brakes lights now working again !