Yanmar Tachometer Sender.

[Norman_E]

Can anyone tell me where to find the sender for the tachometer on a Yanmar engine. Its a 4JH-DTE but I suspect that the senders are in the same place on most. My tachometer suddenly stopped showing anything and I suspect that a wire might have come off somewhere. How does a diesel work a tachometer anyway, as there is no ignition to have its pulses counted like a petrol engine?

 

[Talulah]

On our Yanmar there is an extra lead coming out of the alternator with a bullet connector on it. (I think the wire was white.) That is used for the tacho signal.

 

[Norman_E]

I think I might have found it. There is a fitting with two wires coming out of it in the engine block at the back of the engine on the port (exhaust) side in line with the flywheel. That makes sense if the sender works by receiving a magnetic impulse as the flywheel turns. Am I right? The wires disappear into the wiring loom and are intact so I think the problem may be at the instrument panel end.

 

[earlybird]

On the GM series of engines, the standard tacho. sensor is a pickup looking at the flywheel gear teeth. The mounting is via a threaded hole on the bell-housing. On my 2GM20, at the top position IIRC. Likely to be similar for your engine I'd think. There was no tacho output on the alternator.

 

[VicS]

I think I might have found it. There is a fitting with two wires coming out of it in the engine block at the back of the engine on the port (exhaust) side in line with the flywheel. That makes sense if the sender works by receiving a magnetic impulse as the flywheel turns. Am I right? The wires disappear into the wiring loom and are intact so I think the problem may be at the instrument panel end.

You will find a manual for your engine at http://www.motoren.ath.cx/menus/yanmar.php

There should be details and wiring diagram with colour code in there.

 

[Norman_E]

Thank you Vic, I do have the printed manual but the wiring diagram is totally incomprehensible, as well as needing a powerful magnifier to read.

I found the wiring diagram for my type of instrument panel in one of your links, and can blow it up large enough to read on screen. Now all I have to do is get the panel off as it was screwed on and stuck down with a very tough adhesive.