Overheating light switch wire connection

Hi all, have a 1990 200TDi disco. The bue wire connection in the light switch on the control column gets well hot when the headlights are on. It has melted the connection point on the last switch. New switch assy and is getting hot so not a switch problem. Have traced the wire on the wiring diagram and it appears to only go to the headlight relay. If this is correct could the relay be drawing too much current? Any advice would be greatly received. All systems work correctly otherwise. If you think it is the relay, where is it please?

Heat is a result of Current Flow through Resistance. Therefore you could have one of two problems either too high a current flow or a high resistance joint.
You say it melted the connection point on the last switch was any damage done to the connector on the wiring loom? is so this would cause the problem.
Two solutions i) with a mutimeter measure the current flow through the switch, if this is only powering the relays should be between 0.1 and 0.2 Amps, ii) with a mutimeter measure the voltage drop across the contacts on the switch should be next to nothing if it isn't then it is a connection problem.

Andy

Thanks for that Andy, will get the meter fired up tonight.
John

Andy,
Found and fixed the problem thanks to your help. Did it before the Bosnia trip in Feb but only now had a chance to reply.
The wiring diagram I have is cr..p; for the dip beam the whole supply is through the column s/w and the problem as you suspected was a high resistance which I found between the wire where it is crimped in the pin in the plug. Stripped, soldered and now fine.
Thanks a million.

Well done Slowly it's great when someone comes back and thanks a member who has helped him. Shame that it doesent always happen.