Help! Mystery Alarm on 1993 Yamaha 2-Stroke 225 TXRR

[deepsea79]

I own a 1993 Proline Walk Around powered by a 1993 Yamaha 2-Stroke 225 TXRR.

The other day at the dock I got an oil alarm while the boat was warming up. I checked the oil reservoir on the motor and found that it wasn't being fed by the remote tank. I tested the pump by hooking it up straight to the battery, checked both oil sensors with a multimeter, changed the inline oil filter, and cleaned the connections. I put everything back together and the oil system is working like it should and the visible alarm arrow point to the yellow oil can on the tach is gone. But I still have a problem. The audible alarm hasn't stopped!!! The constant audible alarm comes on as soon as I put the key in the on position and continues while the motor is running. The motor runs excellent throughout the entire RPM range (no limp mode). The engine is cooling correctly as well. I tried disconnecting the pink thermostat wire from each side and the alarm persists. The only way I can get it to turn off is by disconnecting the 10 pin connection going from the main harness in to the ECU. I'm going to check for continuity on the pink buzzer wire today after work to see if it is grounded out somewhere. Could this possibly be a ECU issue? My tach and fuel guage stopped working when I got the initial oil alarm but started working again shortly there after. This damn buzzer is driving me nuts.

Any help is greatly appreciated.

[99yam40]

Possible it was a low voltage as you said the gauges stopped working and the oil pump did too.
check all connections even grounds

[deepsea79]

I tested the continuity on both of the wires coming off of the buzzer. They are good. I also checked the voltage on both batteries and they are good. Lastly I didn’t another check on the wiring harness for any damage and I can’t find anything. I’m running out of ideas and things to check. How could I be getting a audible alarm without a visual? Also, the alarm seems a little quieter (muffled) than the full out low oil alarm. The boat is running and cooling great. What gives? I ordered a used ECU off of eBay yesterday for a good price. I hope that resolves the issue.

[panasonic]

This is your clue

"My tach and fuel guage stopped working when I got the initial oil alarm but started working again shortly there after"

I will assume that both guages lost power and where completely dead...not still having power but with no signal or readings. For example tach still lit up, but no reading on engine RPM.

Fuel quantity Guage?

I believe you have a wiring harness problem , Chafed, loose wires, bad plug or grounds you have not found yet.

[rodbolt17]

I belive some folks have no clue how the alarm system works, the oil transfer system works or how to properly use a multi-meter to test voltage drops.
the yellow lamp has no alarms.
the manual transfer works,use it.
low battery voltage will set an audible.
tone is the same for all alarms.
carefully study the harness diagram.
you will note the alarm buzzer has 12V applied at key on.

[deepsea79]

Update: I installed the new ECU and I am still getting the audible alarm. To date I have checked the following,

Tested oil pump using 12v battery - good
Tested remote oil tank sensor - good
Tested engine oil tank sensor - good
Tested wires coming off buzzer - good
Tested voltage on both batteries - good
Replaced in-line oil filter - good
Replaced ECU - good

The motor is running and cooling great (no limp mode). No visual alarms on the tach. I suppose it might be a ignition alarm that isn’t turning off when I start the engine. The boat never sounded an ignition alarm in the on position in the past.

Thanks again for any advice,

J

[99yam40]

even Rod said it could be low voltage .
My guess would be low voltage to the ECU

[deepsea79]

Can you recommend the best method for testing the voltage going into the ECU with a multimeter. Also, can anyone recommend the best method for checking for grounding issues in the alarm system?

[zenoahphobic]

Just a couple of things.

Reset the system by disconnecting the battery. Usually oil induced alarms, when oil is replenished, requires the key to be turned off and on again of engines like yours vintage to reset the alarm to off. However temp alarm induced go off when engine returns to normal temperature.

If you have done this, then check your temperature sensors by disconnecting them one at a time, to see if alarm goes off, to elimate them as faulty.

You say alarm seems quieter, so measure the voltage across it and compare it to what the voltage is at the battery. A significant drop suggests faulty wiring or dirty connections. If this is so, this gives you a starting point tracing the wiring back to where the voltage drop occurs. It may be just a need to undo connections, clean them and relighted (even if they seem clean and tight) .