2005 Yamaha F150TXRD has high idle

[Lunasea]

Completely frustrated trying to deal with adjusting the idle on my 2005 Yamaha F150……
I have been using YDS program to no avail.
It did show four codes….two not recent 13 Pulser coil and 28 shift position switch. Two are recent 29 Intake pressure sensor and 18 Throttle position sensor.
When I run Diagnosis, everything has a Normal result.
When I run Stationary Test, and try to ISC valve opening….I get an Error message stating Engine is running or shifter is in F or R. Program won’t let me go any further.

Needless to say…it is neither running nor in gear.

When running Engine Monitor, the ECU knows the rpm’s are 0 and I can watch the Shift position parameter toggle between on in neutral and off in either forward or reverse.
Throttle valve opening is 0.7 deg.

The Active Test showed Engine speed 1000 rpm, Throttle valve opening 0.7 deg, TPS voltage 0.728V, and ISC valve opening 67%.


So what is up???

I should note that a very interesting finding is the ISC valve gets extremely hot to touch with key on and working with YDS. Engine not running.

Should also note that shifting lever and throttle lever are adjusted per manual.

Anyone have a clue as to what is going on?
Sure would like to get this sorted.
Any and all advice/experience would be greatly appreciated! Thanks.

 

[JY Marine]

Sounds like the main issue may be around the ISC/TPS side of things, not the basic shift linkage. Since YDS shows 0 rpm, sees neutral correctly, and throttle opening is only 0.7°, it’s strange that it still refuses the ISC test like the engine is running or in gear. The recent TPS code 18 and MAP/intake pressure code 29 are the ones I’d focus on first. I’d check TPS voltage and adjustment, wiring/connectors, grounds, and the ISC valve itself. The fact the ISC gets very hot with key on and engine off is also suspicious and could point to a sticking ISC or electrical fault in the valve or circuit.