Is my digital tach stuffed?

[Twosheds]

Hi from Australia, I am a long time viewer of this site but first time poster.

I have a 2001 150 HPDI model Z150PETOX (US equivalent model Z150TXRZ) with the OEM digital tachometer containing tach, trim meter, oil level indicator and overheat warning. A few months ago I noticed the tach was only reading intermittently however the other functions were OK. Now the whole guage is blank with just a small glimmer of random LED's showing when ignition is turned on. Have checked the harness connections and look OK. The other digital speedometer guage is working OK. Is the digital tachometer stuffed... or am I missing something really simple??

The second question is which guage do I replace it with if it is stuffed? The Yamaha spare parts list shows my digital tacho is no longer available and has been superceded by a newer digital multifunction tacho with extra features. Which multifunction tacho will suit my engine and will I need an adaptor harness to make it work with my existing harness?

[boats.net]

If you have 12 volts between yellow and black wires at tach with ignition on and tach wont power up then tach is bad.
Part number is 6Y5-8350T-82-00 Multifunction Tachometer

[throrope]

IMHO checking the wires isn't good enough. I'd pull every connection apart, clean, pack with dielectric grease and if the problem persists, then replace stuff. I read a white paper I think by Faria that stated the most common issue with tach's is a bad connection.

Yamaha, or for that matter any outboard maker doesn't make the instruments. A search for Faria boat gauges may get you a match.

Good luck and keep us posted.

[Twosheds]

Thanks for the quick replies.

I tested the voltage between the wires as was suggested and my multimeter read 12 volts. I also checked the connections and fuses in the wiring harness and they appear OK (sprayed the connectors with inox - didn't have any dielectric grease). It appears the tacho is stuffed.

I found the replacement multifunction tacho you nominated 6Y5-8350T-82-00 in the parts list. This shows only 1 connector from the tacho to the harness but my existing tacho has 2 connectors. Do I need an adaptor to connect in the replacement tacho or should I just cut whatever wires that don't have a home and crimp in connectors?

[Twosheds]

Just an update....

Installed new multi-function tachometer. Had to cut off the 4 pin plug from the new unit and the two plugs from the existing wiring harness as they were not compatible. Crimped in a new waterproof 4 pin plug to match the wiring and everything now works OK... except for the trim level on the gauge (which hadn't worked for the 3 years I have owned the motor anyway). Traced that to a faulty trim sender unit for which a replacement has been ordered.

Thanks for your assistance, it is greatly appreciated.