switch with 10mA

Suggest in-line fuseholder (e.g. RS Components 414-601). Lowest value 5 x 20mm fuse I can find quickly is 50mA (RS 480-4317), which won't protect against long-duration, low level overcurrent, but should save the switches in the event of a direct short to the supply. Look for 10mA 5 x 20mm fuses from other suppliers for long-term solution (or use miniature PCB mounting types).

Increase thickness and width of tracks to a point that any fusing will act BEFORE the PCB track acts as a fuse.

I had to do this on a huge (3/4 Ton) line printer about 30 years ago. I had to solder thicker copper wire the length of all the tracks on the PCB to prevent that happening. It was when I worked for Univac on their 770 printers!!!

I have had to do it from time to time on other equipment where the designers forgot such details......

If V = 12 V:

Test switch with current limiting resistor of 12V/10mA = 1.2K, in line with the switch.

It is likely that the ECU will still work with this in line resistor due to high input resistance.

Guest - please register & give us some feedback. It is very frustrating to take time out to give advice (good or bad) without even some indication that it has been received.

You are right John, I have rated this comment as good for that reason, sadly you and I cannot expect any "quality" of manners in someone who only logs on as "guest"......we both know that as we see it time and time again....

I feel that we should re-write the name "Guest" as "Jest"!What do you say to that?