Temp gauge question

[Halfast]

I have an 04 Launch and had the boat winterized in Nov. 11' at dealership. I just pulled boat out and summarized boat a tried to run boat up to 160 but gauge light didn't come on and gauge didn't move. Then it bounced up to 135 then quit working? How do I know if it's the gauge or sender? Where would be the best place to replace either? I live in Fort Worth TX

[sydneyACE]

I would check your gauge's ground/power wires (behind the dash).
It sounds to me like you have a bad connection/shorted wire somewhere.
If the sending-unit was bad, the light should still work. I would try the sending-unit as a last-resort only.

The gauge itself could be bad, but def check all the wires first because that's a way cheaper/easier fix than replacing the gauge.

Good luck!

[lively]

Go to sender and remove wire and ground out to the block .. This should peg the needle out thus proving if the gauge is bad or
Not . Or if u have a volt meter just check continuity between the signal wire from sender to gauge and so on till you find the break or loose connection

[DKJBama92Mariah]

Was the boat in the water when you ran it or did you hook it up to a hose on the trailer? The coolant temp gauge will not function without cooling water. If you did run the boat with cooling water, the raw water pump impeller will be destroyed and need to be replaced.