SX/LX150TXRY no overtemp indication on TACH

[FabricGATOR]

Hello Folks,

I have confirmed that I do not get the flashing thermometer indication on either tachometer on my twin year 2000 ox66 engines.

The original digital tachometers were replaced with 6Y5-8350T-83-00 digital tachometers due to sunburn (unreadable digits). I never did verify until today that they do not indicate overheat. Yesterday I had a WOT overheat after a minute and a half and I could not see which engine it was that was overheating.

Today I drained the main oil tanks and verified that I get the proper flashing oil indication on the specific tachometer, and that the tanks refilled within the three minutes (alarm off at 1:40, pump off at 3:00).
Then I tested the thermo switches by touching each pink bullet connector to its corresponding black connector and I did not get either engine/tach to report which engine had a simulated overheat.

Did I do something incorrect or incomplete? Can you guide me to troubleshoot this further?

[FabricGATOR]

Additional info:

I do get the audible alarm, just not visual indication on the tach.

Both engines go into protection mode when one overheats.

A schematic on the system and an understanding of where the signal is generated and what that signal is would be helpful.

[boscoe99]

Find the two trim/oil connectors that are in the engine pan. They will be connected to a harness that runs from the motor through the boat and on to the tachometer.

Now find the connector (one of the two) that has a pink wire, an orange wire, a gray wire and a black wire attached to it. Find the gray wire and follow it back just a tad. You should find a female bullet connector. Is there anything plugged into the female bullet connector?

If you don't understand what I mean by the trim/oil connectors then holler.

[FabricGATOR]

Both of my pink, gray, black and orange connectors are empty plugs on the vessel side. Trim senders were removed for replacement (inop) but then deferred due to cost and in*****cy.

On the engine side I do have a male gray bullet connector (open / no connection) and a blue female bullet connector (open / no connection)

Thank you for your assistance.

[FabricGATOR]

censor

Now why in the world would they censor the word
in_acur_racy ??

[FabricGATOR]

Got it , thanks.

I'll make up a jumper from the gray trim/tilt harness to the gray bullet connector.

Luckily, I have some of those Japanese watertight connectors / pins in stock. I was going to make up a blank anyway to protect that trim plug from corrosion exposure.

[99yam40]

I do not think he is saying there should be something plugged into it, just asked if there was.
I could be wrong

[boscoe99]

I was just trying to get some fact finding done. I am not personally familiar with all Yamaha models over all years so sometimes I rely on what I can see in a service manual. Sometimes, what I see does not correlate with what I know. So it is a learning curve for me and hopefully the owner.

Looks to me like Yamaha uses a connector from the trim sender that attaches to the trim/oil harness that runs up to the tachometer. A single wire with a bullet connector comes from the engine harness and attaches to the connector. It carries the over temperature ground. This is considerably different from the way that other Yams are wired.

See illustration below as to what I think is happening.

[FabricGATOR]

You are correct sir, thank you for the inspiration.

The gray conductor bullet connects to the trim sensor and thus communicates to the gray wire on the 4 way connector.

Nice catch Boscoe, your assistance is greatly appreciated.

I improvised a jumper for testing and ops check - normal.

[FabricGATOR]

I do not think he is saying there should be something plugged into it, just asked if there was.
I could be wrong

Sorry 99YAM40, I skipped a few points of discovery.