Truck I was in yesterday had tacho running 3 hours behind! Time shown on display was correct but flashing. I couldn’t get it to reset from the tacho panel. I think it was a Seimens. Truck was a 7.5 tonne DAF and dash speedo panel had red light which I’m sure relates to tacho.
Back at the base nobody had a clue about it and said nobody else had mentioned it.
Any ideas on how to reset it? I’ve just been asked to do another shift for them on monday through agency, so I might as well try and get it sorted.
From memory! If i remember you eject the draw pull out the plastic divider thats in disc2 slot. Press M and hold, this gives you access to the time and date, adjust as required. Press and hold M again then close draw, it should spin round like mad and settle down with clock correct not flashing, open draw again refit plastic divider and insert you card.
IIRC it should update its self. you just need to open and close the drawer but without a tacho in the head. this is what I did when the clocks changed and it worked( was told by another driver at work)
Maybe the problem was that I think there was a blank in the 2nd driver slot. I could alter the time on the display via the menu buttons, but when I reinserted the drawer it had no effect and the time display was still flashing. If I’m in the same truck on monday I’ll let you know how I get on, thanks for the help 
These type of tacho heads do not require a blank, or plastic protector, disc in slot two. The only time a disc should be in slot two is when the vehicle is being operated by two drivers. You can adjust the time but with a disc in either slot it cannot update. Remove any discs from the second slot and leave it empty and adjust the time before putting your disc in position one.
Imp:
From memory! If i remember you eject the draw pull out the plastic divider thats in disc2 slot.
That will likely be the cause of the problem, it has been unable to make small time adjustments while a disc has been in position two.
Imp:
open draw again refit plastic divider
No, don’t do that. Bin the plastic divider as these type of heads do not require one. The operating manuals for this type of tacho head state that a disc should only be in position two when the vehicle is double manned.
Oh right well every truck with that type on our fleet have a plastic disc in!
Imp:
Oh right well every truck with that type on our fleet have a plastic disc in!
Which means that every truck on your fleet, with that type fitted, has a tacho head that won’t be able to work correctly. 
