I have a 1999 R170 recently bought. At times the indicators will stop working and the warning light will display on the panel. After much searching I find that by moving the main lightswitch/fusebox I can make the fault come and go as I like. has anybody any experience of this? and can you suggest the cure. it would be useful if someone had a wiring diagram to show me. Is there a ground point in this area? All other functions are OK.