Schematic for F90TLR

[pstephens46]

as Boscoe has explained, your SM does/may not show the Command Link wiring - but its there.

Here are the "S" and "W" connectors as they come from the factory - not connected to a sensor:

The purpose of measuring water pressure is obvious. What is this speed measurement? Speed of water flow through block? 2:44am and I can't sleep....

[fairdeal]

The purpose of measuring water pressure is obvious. What is this speed measurement?

[rodbolt17]

first clear the codes, don't really care what set 300+ hours ago. then start the motor and see what comes back. you can disconnect any sensor you wish with the engine running. it should step up the idle speed but wont hurt anything.

[jackmanjls]

===============EDIT ALERT ================
11-6-2017 ==> I took another look at the 5vref today and it isn't a problem. Previously the placement of the meter probe ground was not good ground.
I went directly to the ground from the battery and found that the 5vref was solid as a rock.
========================================

I did a search on the internet for "clear error codes for yamaha outboard" and didn't have much luck so they weren't cleared.

I put the YDS back on the motor and ran some tests.

The Diagnostic Record displayed the previous errors (37,18,23,28,29) that I tried to clear but also gave me a msg:
1. Check no air leaking in intake passage

Any ideas on what this might be?

Then I ran the Active Test: ISC valve opening test for 5 mins and monitored the 5vref. The ref varied from about 3.20v to 2.21v. This is a large fluctuation for a reference v.

Also ran the Active Test: Fully open ISV valve. This test doesn't die on accel but very close to it. There is some hesitation before the accel.

Next I focused on troubleshooting the problem with the 5vref. I disconnected the TPS, sensor assembly and CL connectors S and W while still monitoring the 5vref. The intent was to find something that loaded down the 5vref. The voltmeter didn't change it remained at ~3v. So, nothing seems to be loading the 5vref.

One additional observation. Yesterday, I reported that when I monitored the 5vref that it was 5v BEFORE I initially turned the key on. Today, I go out and BEFORE the initial key turn and the value is 3.3v.

At this point I'm thinking that the ECU 5vref appears to be a problem.

Any ideas?

=== EDIT
I am going to try and disconnect the orange wire at connector L pin13. This will completely isolate the ECU 5vref. If I get the 5v, from the ECU, then I'll look deeper if not then that tells me the 5vref at the ECU is not referencing properly,ie, it's hosed.

==== EDIT
Connector L buses together the 5vref to other sensors. It looks like the 5vref from the ECU can't be isolated. When I turn the key on I get an audible and the ECU doesn't put out the 5vref. Bottom line is I can't isolate the 5vref from connector L.