Light switch melting

[fishboy]

Looking for any ideas/direction. My light switch on the dash failed (later determined it melted internally). I replaced the switch thinking it was just worn out. However, the switch failed again after 1 use of headlights. I removed the switch and the internals were melted like the original switch. The wires stay cool when just the parking lights are on but become VERY hot when the headlights are turned on. I checked voltage and only have @10 volts at steering column when headlights turned on but 12 volts when headlights off. The only change was that I cleaned grounds on all of my parking lights and tail lights (not sure how that would affect it). Thanks in advance!

[JEEPER]

Did you leave a ground off? You said you did nothing else. Are the voltage readings with the engine running or not? I would look for the headlight grounds and be sure they aren't on the same ground screw as the parking lights.If you find nothing I would reground the head lights then see it the switch gets hot. Good luck, Bad grounds do strange things.

[So Cal Mark]

Fiat routed all of the current through that cheap little switch. It's best to install a relay upgrade in the system

[spider2081]

Cleaning the grounds would make a better contact (less resistance) resulting in more current flowing through the switch.
The switch is designed to carry the current of a properly operating circuit. If you increase the current draw by installing bulbs that are a different part number then the original the switch can easily be over worked.
Are all the fuses associated with the lights the proper value?
I agree with Mark's suggestion to install the headlight relay mod.

[GeorgeT]

Install headlight relays and this problem goes away. The original design results in full headlight amps to go through the ignition switch, the column light switch and the dash light switch. Relays eliminate high amperage going through these parts and reults in brights lights as well.

[fishboy]

Thanks Everyone,
I think I may go the way of the relay AND double check all grounds once again. I have a feeling that as I clean the grounds I am improving voltage flow but with so many old connections etc. I may be constantly chasing my own tail.