Wiring engine hours counter to alternator

[nigelmercier]

Did you connect up the new meter to a permanent supply first to have it match the hours on the original? How did you do that?

As you say, "connect up the new meter to a permanent supply first..."

I didn't know what mine should read, so I started at zero. I've got a fully working unit now, by taking the memory chip out of the old tachometer and putting it in a replacement one.

 

[nigel1]

I have an hour meter from RS following advice an earlier thread 2 years ago
I have a Volvo md 20 20
The hour meter uses 2 wires ( provision for 4)
The blue wire goes to the same terminal on the alternator as the large black wire
The red one goes to the terminal marked "D+"
The hour meter only works of the engine is running & does work on tickover
I have checked it several times & , for example, on a 15 hour run it is virtually dead on

Just done the same with one of these meters


Positive connected to the D+ terminal on the alternator, and the negative to the main negative terminal on the alternator.
With engine stopped, there is no volts across the two terminal, with egine running, measured voltage was 14.2.
It was a lot easier to connect at the alternator rather than try and get into the ignition harness.