Hello , hope i'm not repeating posts if so please tell me , got problem with my Focus ; when cold in the morning starts no problem , no smoke no rattles everything's fine , drive few miles or even longer leave the car standing for half an hour or so and can't start , glow plugs are new , service just done filters, oil etc ,checked that there is no voltage on the plugs , gave him 12 v from battery when doesn't want to start and starts straight away ,noticed that glow plug light comes off after a second or second and half when doesn't wanna start , when normally stays there for few seconds , looked up under bonnet and looks like there are 3 relays , what You suggest ? changed all 3 of them ? help please... many thanks

 

Don't know at all on these but on some the CTS input is used to determine the glow plugs 'On time', just a thought as if it's giving duff info it may be saying it's hotter than it is and so the plugs arn't staying on for long enough, clearly it's something to do with the supply to them.

Martin