[paulNM]

I have a 90 HP Mercury Motor - I have replaced the impeller. Overheat alarm comes on continuously even without motor started. I have run the motor at idle - engine block and heads are not hot, but alarm continues. I am assuming the sensor or wiring is the cause??? Any comment or help would be appreciated.

[Silvertip]

Disconnect the sensor. If the alarm quits, the sensor is the issue. If not, the module is probably toast or the tan wire from the sensor is shorted to ground (that's what the sensor does).

[pattymilink]

Where is the heat sensor located on the engine block to disconnect it?