Warning Horn Merc 225 EFI

[Tony LiCausi]

I am completely stumped. My 2001 while the ignition is on not started a continuous beeping with an alternating oil and temp light. So far I have changed thermostats, temp sensor, rebuilt water pump. I also changed the on board oil tank, emptied the on board water separator to check for water. The temp while running is 140 and oil consumption is normal. I jumped the wires to the oil sensor and with the key on, it changes to the oil light with the 4 beeps every 30 seconds or so.

Please help
Thanks

 

[Texasmark]

Not savvy with the 225 nor EFI. On smaller 2 stroke engines you have an oil level sensor for the oil reservoir which when low gives an intermittent alarm or the engine block over temp (195F) solid alarm. The engines that have the intermittent oil alarm have an alarm module which modulates the oil fault so that one can distinguish it from the OT alarm. On at least the fairly recent 90 and 150 2 strokers, the thermostat opening temps are 143F, one stat on the 90 3 cyl and one in each bank of 3 cylinders on the 150. The OT sense wire is tan or tan with light blue stripe and the oil alarm is light blue with white stripe.

The alarm sounds on a grounded sensor and the engine block is usually the tie point as the battery - cable is attached there. Both sensors should be open circuited unless you have a valid alarm.