Temp gauge doesn’t work

[Ryangio72]

Hi, my temp gauge does not seem to be working. It stays pegs all the way even when the boat is not on and hasn’t ran in weeks. How do i go about making this functional again. I have a 94 Starcraft 1710 with a mercruiser 3.0.

 

[karayj]

The 1st thing I did when this happened to me was to test the gauge and connections. Disconnect the wire to the sending unit and ground it / See if he gauge reacts to it if it does you gauge is fine most likely the sending unit. if there is no reaction on the gauge then it could be a bad wire or bad gauge.

 

[achris]

These instruments are 'unpsrung', they will read anywhere when the power is off. Only when power is on is the reading 'valid'.

First, check you have both 12v and ground on the gauge. If you have, then disconnect the tan wire from the gauge and see if gauge stays at full cold. If it doesn't, then the guage is faulty. If it does, then reconnect the tan wire at the gauge and disconnect the tan wire at the temp sender on the engine. Gauge reading correctly now (full cold)? if so, replace the sender. If the gauge is still pegged at full hot, then find the damaged wire. It'll be shorted somewhere between the instrument cluster and the engine sender.

Chris.......