1989 Yamaha 90 hp oil display wrong

[cub@2185]

I have a 1989 Yamaha 90 hp model ETLFJD with a multi function gauge( tach, trim & oil indicator). It's shown the correct oil levels for the last 20 years but now always shows the yellow indicator- (middle icon)-even with a full tank of oil. On advice from a local boat repair, I replaced the multi function gauge-no difference- and then the oil sending unit in the tank- still no difference. (And I'm about broke now.)

My sealoc book shows there to be a "control unit" that could be bad but shows it to be either behind the multi function gauge or in the switch, throttle, shifter assembly OR on the motor. It is not behind the gauge or in the switch module and if it's on the motor, nobody can find it.

I can take the float out of the tank and move it until the low oil warning buzzer comes on but it still shows the middle oil indicator on the gauge.

My questions are:

1. Is the control unit the problem or something else?

2. Where the heck is it, if that's it?

3. If that is it, do you know the Yamaha part number?

4. Without fixing this, could the motor get the wrong signal at some point and suddenly shut my motor down to idle?

ANY help is greatly appreciated. This has been going on now for about a year. Thanks!

[99yam40]

have you checked the wiring?
It is always better to test until you fine the problem and then buy only the parts that are needed

[cub@2185]

I've checked it for broken wires, loose connections, etc and didn't find any. The local repair shop was supposed to have also checked and on their recommendation, I replaced the two parts mentioned.

[rodbolt17]

find a real repair shop with real techs and real multimeters.
the items you replaced are easy to test.
an open circuit on the green/white wire will trigger a yellow lamp.

[dmcneane]

2001 200 hpdi

I too have a similar problem with my 2001 HPDI's. Both multifunction tachs are displaying a flashing center bar. I have the 3 bars to indicate oil level. It seems unusual to have both tach's indicating the same remote tank oil level at the same time. Both tanks are full. I've checked and rechecked all of the wiring and related components on both engines. Both engines work fine, i.e. transfer oil. I even had a certified Yamaha tech take a look at the wiring, etc. We even replaced all the cabling from the remote oil tank including the multifunction tach with his "test" parts. After reading this post I am leaning toward the Yamaha 61B-85830-00-00 CONTROL UNIT ASSY. as the problem. Any and all thoughts would be appreciated.