Honda sensor

garyk · Posted: Fri May 23, 2008 3:03 pm Post subject: Honda sensor

Honda Over Heat Sensor
Last week I visited a friend in Seldovia, Alaska. He has an Armstrong 28 ' Cat powered by two 2002 Honda 115. The boat had been out of the water all winter. Both engines started in a normal manor. The overheat red light and alarm sounded as soon as the starboard engine started. After several restarts and shut downs, it was noted the stream from the starboard engine had a good flow ( much better than the Port engine) Would the overheat sensor detect an open thermostat? The manual said the engine , if overheating, would shut down or go to reduced power. With this in mind we went out for a 30 minute test run. I muffled the horn by taping over the sounding hole. Both engines ran well at 4000 rpm. We went fishing. Put about six hours on the engines over the next several days with a blinking red light and muffled horn. The engines ran just fine.
To get the boat to a Honda service shop involves picking up and dropping the boat driver by air, Alaska complications.
I told my friend I'd run this by you guys. Simply replacing the sensor should solve the problem or maybe the thermostat. We could not find the sensor that controlled the red light and horn. Is it internal?

Thanks for your help, Gary King

tsturm · Posted: Sat May 24, 2008 1:04 am Post subject: Re: Honda sensor

Les Lampman · Posted: Sat May 24, 2008 6:29 pm Post subject:

There is no red light that blinks in an overheat situation. There are four lights in a BF115 installation; 3 are red and 1 is green. The green one is for oil pressure; it should be on steady any time the engine is running. The first red light is for either over temp or low oil pressure (whichever is occuring; the green light will go off if it's low oil pressure). The second red light is for the alternator; it will come on if there is no output from the alternator. The fourth light is the Check Engine light; it monitors the fuel injection system and blinks a problem code if it exists.

In an overheat condition you will get a steady red light and a steady horn and the ECM (electronic control module) will reduce the rpm to 1800. If the temp doesn't drop within 10 seconds the ECM will take the rpm to 1000. If the temp does not drop within another 10 seconds the ECM will stop the engine.

I suspect it was the Check Engine light that was blinking rather than the overheat light.