Tohatsu 20 HP 2018 problem

[mark DV]

Hi, all!

I have an issue with Tohatsu tiller 20HP.
The problem is that every time when I lower the speed/RPM from (relatively) high to minimum or near the minimum, the motor makes a strange, not right sound, starts shaking/vibrates erratically and the red light lightens up.
First several times when it behaved like this I stopped the motor immediately. Then after some time tried to start it again using the rope but it did not allow me. It seems like it was engaged in the gear. Then when I tried to switch it from neutral to start and neutral to rear it would allow me to switch only to forward but not to rear. I had to pool/push the handle several times and once even to reach the propeller and turn it when it was engaged, and only after that I was able to start the motor.
Last time when it happened I decided not to stop the engine due to circumstances and the motor seemed to work normally after some time but the red light did not shut off for a few minutes before I finally stopped the engine.
Any ideas where I should look?
So far, I disassembled the lower unit and everything looks pretty good. Nothing wrong is in there.
Is it possible that the problem is in the shifting rod, it is either a bit shorter or a bit longer? There is a possibility for small adjustment but the question is why it could go off.
Also does anyone know if something similar to the OBD II reader is available with these motors?
Thanks a lot! Any suggestions will be highly appreciated!

 

[pvanv]

What exact model (not year)? Is your oil level too high? Yes, there is an adapter to attach the EFI motors to a laptop, but it's not cheap.

 

[mark DV]

Yes, exactly. The oil level was too high. Way too high. I’m not sure how I could make it like that.
But I initially stuck with the idea that this is a gear/shifting problem and checked the oil level only after I took down the lower unit.
And after that I started to think this way too. It may be that the red light and motor shaking after lowering RPM is due to high oil level and the shifting problem afterwards is just because I stopped the motor too quickly even without putting it to the neutral.
I really (really!!) appreciate that you pointed it out to me.
But I still cannot get why stopping the motor on gear could cause the problem afterwards after I shift to the neutral and attempt to start.
Thanks a lot for helping me! This confirmation is very important for me. I wasn't sure what to do - assemble everything back and try to run the motor or look further for something else.

 

[mark DV]

But I still cannot get why stopping the motor on gear could cause the problem afterwards after I shift to the neutral and attempt to start.

Any suggestions on that?
Thank you!

 

[pvanv]

High oil can cause aeration. That persists after stopping.

 

[cyclops222]

Why do you stop a motor while still in gear ?

 

[mark DV]

This is because I was too much disturbed by the red light and unusual motor behavior and I wanted to stop it immediately. I didn't even notice at that moment that I hadn't shifted to neutral.
Could it really cause a problem afterwards that I was not able to shift the gears and start the motor until I manipulated the propeller to realign (?) the gears in the lower unit?