DIY and FIXES
On my sailboat, when i got it, the tacho and hours meter LCD instrument was dead. It is marked VDO Model N02070009 or Volvo number 873660.
I wanted to find out the current state of the hour meter and have found a perfect solution to this on this page. If you are not able to do the programming of arduino, there are other options too:
Read more at http://www.ybw.com/forums/showthread.php?312217-Tachometer(VDO)-Problems-on-Volvo-Penta#xdmG6rBtqAHj2LJL.99