Temp gauge testing

[milepostje]

My temp gauge is not working on my bike I just bought. Previous owner says it has never worked. So I read about the possibility of a bad ground. Installed a new ground wire from housing to frame. My dash is off because I sent radio to Pete to do an upgrade. So my question is, how do I test to see if I'm getting power to sensor? With key on, is there supposed to be 12v at the connector that hooks up to the sensor, or do I not understand how it works? Wire is yellow and white

[JHD]

Remove female connector to sensor. Turn on ignition. Temp gauge should read C. Next (quickly) ground the connector, gauge should read H. If this checks out then your gauge and wiring is fine and your sensor unit might be bad. Might be, because others have found that the grounding is not sufficient to the thermostat housing and will run another ground to the housing. You can do a search on the forum to find out what others have done to solve this. If the ground wire doesn't change things you will most likely have to replace the sender.

To test the sensor remove it than hook up your DMM lead preferably an alligator clip on the terminal tip so you are able to hold and suspend the sensor in a pot of water up to the top of the threads (don't touch sides of pan). You will take resistance measurements with your other lead probing the sensor end at 176 & 212 degrees. The readings should be 52 & 27 ohm's respectively.

[milepostje]

Thanks. I did what you said and all the wiring and gauge tested out. I decided to just start the bike and let it run for a while, and the gauge seemed to be working so the sensor must be good. I guess the whole problem was just the ground. I'm glad that's all it was because I sure wasn't looking forward to try and pull that sensor.