Originally Posted by sea_quest
tachometer not doing anything apart from when i'm turning the engine over its working as soon as it starts nothing.
or does anyone know of a wiring diagram i download from somewhere.?
Are you saying that the tacho only displays a reading when you have the starter motor engaged? Has it always been like that?
You should have 3 wires going to the tacho:
- + 12V (either live all the time the main battery switch is live, or more commonly when the ignition is in "run/on" (not "start/crank").
- "Signal" - the feed from the engine which varies with rpm.
You may also have a extra wiring for:
- Backlight (often wired into nav light circuit),
- Any oil, temp or other warnings that are displayed on fancy multifunction units.
Assuming I've understood your problem right, and its been like this all along (or following some recent change - and not happened randomly) then it sounds like you have inadvertently connected the +12 V connection to the "start/crank" wire on the ignition rather than the "run" wire.