I have just replced the globes and still the dash lights arnt working properly, traced wiring back to light switch and thats fine, also traced back to fuse box and probe shows good power source , I have checked and cleaned the earth at fuse box and instruments,
It seems that somewhere there is a substantail drop in power,
at the rear of fuse box a yellow wire heads off towards the engine bay, I was going to follow this one back.
any other thoughts would be appreciated.

like to add that this is a great site and while ive only joined recently the help is fantastic, thanks to allthose who are active in solving these sort of issues.

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yes it works fine, so we have strong power supply from fuse box to light switch, stat knob is fine and tests reveal all is ok, from the light switch back to the dash lights indicate a severe drop in power supply ,even when the knob is turned to the bright