EST1 Open

[alldodge]

The analog gouges are simple enough, need 12 to 14 V, ground and sender providing variable ground. Your reading low so resistance is high or bad connection.

Check your connections, voltage and with power OFF measure resistance of sender to helm ground at the gauge

 

[dingbat]

Now if I can just figure out why the temp gauge isn't reading properly. New gauge, new sender, actual engine temperature at 158F, [varified with scan and laser temp gauge] and yet the gauge reads at about 200F. Very strange...

Laser temp gauges are notorious for being inaccurate. Plus or minus 10% is common. Not to mention they read surface temp, not the actual water temp.

Suggest you remove sensor and confirm calibration (accuracy) using a pan of boiling water (212F) water.

Since the sensor is analog, reading resistance, I would also put an ohm meter on the wire feeding the gauge. Should read 0.00. A bad wire or connection will affect the reading

 

[300sflyer]

The new gauge is reading high once the engine is fully warmed up, rather than low. As stated, both the engine ECM scan, and my lazer temp gauge confirm this. My laser temp gauge is spot on. Something must be going on with the sender wire between the engine and the gauge. I may try running a new wire, just to see if that makes any difference.