Wednesday 19 October 2016

Tacho ups and downs

Erin Mae's new tachometer arrived this morning – that was speedy, and very exciting (if you like that sort of thing). However, there's little photographic excitement to be had from a rev counter sitting on the kitchen table – photos will have to wait until installation.

I spent a couple of hours (such is retirement) examining the instrument and its various connectors. It had come with a wiring harness to connect it to the old system, so I was busy comparing the wiring diagram in the manual, the wiring diagram for the old tacho in the engine manual, and the actual wires in the bits and pieces they'd sent. The more I looked, the more confusing it was – there seemed to be a lack of logical consistency in it all. I rang the supplier, but they didn't know. However, they did give me a name and number for technical support from VDO – something I'd searched for in vain on their website. It turned out he's on holiday till Monday, but an email was a good way of getting it all put down in black and white anyway.

Being at home, I can't simply get on with taking the old one out and seeing what works. I would also rather be safe than sorry – don't want to blow anything by mistake. It's not as though I haven't got anything else to do – there's all that accumulated mail from two months of cruising waiting to be dealt with…


  1. I think a photo would have been a good idea! I would say that, apart from an earth connection and a switched +12V connection, the important wire is that which goes to the engine alternator's tacho feed terminal. On my new domestic alternator there is a "W" terminal for this purpose; I assume there is an equivalent on the engine alternator. Sometimes, I understand, the tacho output from the alternator just emerges from the innards of the alternator. Does your new one have an hours meter built into it as mine does?

    1. Maybe I'll put up in a new post the photos I emailed to the technical guy, along with a bit more detail about my concerns.