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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10900
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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The warning buzzer goes off temp sensor immediately after

Customer Question

The warning buzzer goes off for the temp sensor immediately after boat is started cold. I know the engine is not warmed up yet so is not overheating. If I unhook the tan/purple wire at the shifter console and start the boat it does not sound. I checked the wire from the sensor all the way back to the console and it is not open. Does this mean the sensor is bad or could it still possibly be the warning module causing the issue?
JA: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?
Customer: I just replaced the water pump as well to rule that out
Submitted: 12 months ago.
Category: Boat
Expert:  Tan replied 12 months ago.

Hello. My name is Tan.

Could I get the make, model and serial number of the engine please?

Customer: replied 12 months ago.
95 Mercury 115 outboard 2 stroke 4 cylinder.
Model# *****
Mfg# *****
Expert:  Tan replied 12 months ago.

Do this disconnect the tan/blue wire on the temp sensor at the top of the cylinder head. Turn key on does alarm still sound?

Customer: replied 12 months ago.
Disconnected the sensor where it enters the block. Warning still sounds.
Expert:  Tan replied 12 months ago.

Ok at the front bottom of the oil tank disconnect the sensor? Does alarm quit?

Customer: replied 12 months ago.
Shut, I have the cover back on the motor now as it has gotten too dark to see for tonight. Can you tell me what to do if it sounds after that it doesn't. So I can try tomorrow?
Expert:  Tan replied 12 months ago.

If you still have an alarm you will need to find where the wire tan/blue is shorted to ground.

Post back with findings and questions.

Customer: replied 12 months ago.
The wire is not shorted to ground. I have checked the wire from the shifter module all the way back to the sensor to ensure it is not open.
Expert:  Tan replied 12 months ago.

Ok then you will have a bad oil warning module.

Customer: replied 12 months ago.
Ok, not temperature sensor then?
Expert:  Tan replied 12 months ago.

No as you disconnected the temp sensor and the alarm was still sounding. So we have eliminated that leaving only the oil tank sensor and the module.

Customer: replied 12 months ago.
Ok, so I plan to unhook the oil sensor. Try to run the motor if alarm still sounds then replace module if the alarm goes away then replace the oil sensor. Sound like the correct course of action?Thanks a ton. For your help!
Expert:  Tan replied 12 months ago.

Your welcome...........Thank you......Tan

Oil warning module P/N 14857A11, oil sensor P/N 12886A6.

Post back if you need further assistance.

Please don't forget to positively rate my help as that is the only way I get credit for helping you.

Thank you......Tan

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