The needle on the temperature gauge of our 04 Tahoe Z71 dropped to the right the other night. Nothing was hot, I could put my hand on the hoses, so we drove it 75 miles home. Replaced the temperature sending unit the next day, and now the needle goes to 240 when the key is turned on. What am I missing here?
The CTS and guage use the same sender so i would suggest you use a scanner and check the CTS temp. GMT800 uses the same sender by way of the UART data to supply the info for the PCM and cluster. You may have a bad cluster since you did not say the SES light went on at around 250F.