Thermostat Or Sending Unit Going Bad....any Ideas?

[Kramer]

I have a 97 SC400 and the sending unit or the sensor must be going bad that reads engine temp............My needle is pegged past RED HOT, but the engine temp at the sesor is only reading 174..........everytime. It may be a bad ground also. Any ideas? Anyone else ever had this issue and were able to fix it? Thanks in advance for any help!

[92Lex]

Is it pegged there even when the key isn't at the "on" position? What are you using to determine that the CTS is sensing 174 degrees? Have you pulled out the thermostat and checked it? Would help if you could give more info.

[menappi]

Maybe the cluster is messed up?

[Kramer]

Maybe the cluster is messed up?

Well I think it may be a grounding issue. I have pulled the engine cover off and temped at the sensor with a digital temp gauge and it typically reads 170 degrees or so. The needle is pegged up above the red on the dash. I have replaced the sensor and still the same thing. As soon as I start up the needle just rises above the H. Now when I ground the needle then it drops to the C. When the car is off needle falls. but the needle is always on the H as soon as it gets cranked up. Im not sure what else to check. It could possibly be the cluster, but it just started doing this. Any help would be greatly appreciated!!!

[menappi]

Yea sounds liek you got a wiring issue, bump for some help.

[Kramer]

Anyone else have any ideas???????