Hi I have a 2006 daf of 55 220 oil tanker(it has 2 isolator switches both of which seem to be killing power when used), couple of weeks ago it wouldn’t turn on no dash lights etc, can hear lorry “clicking” when key turned but nothing on dash and wouldn’t start, managed to get it to start by earthing the starter relay but lorry won’t charge, no gauges working, indicators not working but head lights will turn on? Any suggestions would be more than welcome. I’ve replaced entire fuse board
Sounds like a faulty relay in master switch circuit. They can become slow to turn on and off then fail completely. If vehicle is pet reg’d the master switch must kill the relevant circuits within 10 seconds. It must also operate correctly for the slp scheme.