Honda bf130 temp light on

I have a 2004 honda 130 with the temp light on. The engine is not overheating and not throwing any engine codes or alarms. The light stays on even with the engine cold and not running. As soon as the key is turned to the on position the temp light comes on. Engine has a new thermostat and both temperature sensors read the same on an ohm meter. They also match the readings on the other motor (twins). Is there anything else that could cause the temp light to remain on?

The light first came on last trip out. Engine was not peeing at start up, standard procedure for winter fishing here in Alaska as the plastic T in the line always freezes. Solution is to pour hot water on the the fitting or let engine idle a few minutes until it thaws. Light came on while idling, I shut engine down and let it set 5 minutes before restarting. Engine fired up and started peeing immediately, business as usual, however temp light remained on. Ran trip pretty timidly on engine as light stayed on, but it ran flawlessly and did not feel hotter than the other engine. Shut it down and used other motor to troll for a few hours and light came back on as soon as key was turned to on and has remained on since.

Any suggestions? Thank you.

One more comment. It's a steady red light, not the bright flashing one that normally accompanies an overheat situation.

Is your light in a square housing with the green light? Or is it in a round housing with 3 other lights? Or is it on a panel as an individual light?

It operates from a ground from the ECM.

If it is in the square housing, sometimes it picks up a ground internally. You can double check by finding the red lead going to the light/housing and disconnect it (only the red wire). If the light stays on, then it is probably internal...if not then it could be that the red lead is shorted to ground somewhere between the light, the engine, or the ECM. Finally if it is not grounded, then the ECM may be faulty.

Mike

Thanks hondadude. It is the square housing with only the oil and temp light. I tried switching ecu's already and made no difference. Bill try to follow the red lead this afternoon.

Ok, if I unplug the red lead from the box the light goes out so I'm assuming the problem is elsewhere? Also, I can completely unplug the ECM and the light stays on. Is there somewhere in between that commonly causes a problem? The wiring is pretty much self contained and protected inside enclosed tubing from the helm to stern. Not much access or possible way to get grounded inside there.

More info on the condition: when the key is first turned on both the red and green light illuminate as normal. After about 2 seconds the green light goes out and the bright red one dims to a faint red. It's not as bright as when the alarm flashes if that makes since. Once started the green light comes on and the faint red one continues to stay light.

Any suggestions on where to check next? Thank you

Most likely, there is corrosion either in one of the connectors or inside the wiring itself.

All you can do at this time is follow the red wire to the connector that goes to the main wiring harness, then check the 14 pin main wiring harness connector at the engine.

If you disconnect the red wire at the light and leave the ECM disconnected, you should be able to connect an ohm meter to the red wire and ground and check as you go towards the engine. I sounds like a high resistance ground...maybe 150 -200 ohms (just guessing).

If you have it going into the main wiring harness at the helm but you do not have it when you check at the 14 pin connector on the engine harness...it is in your wiring harness. If it is still there at the engine, then it is somewhere in the wiring harness.

If you do not have a wiring diagram to follow, download this owner's manual. There is a wiring diagram at the end of the manual. It may not be the same year as yours, but the wiring is the same.

Mike

Thanks again Hondadude, you know your stuff! Very slight corrosion in the 14 pin connector. Killed the power, hit it with electrical cleaner and a wire brush now the light is off. For the record ohms measured 156, you called it spot on!

thank you

Good deal!