ObeFastOne

I'm having some problems with my truck and sense my truck has an LS series motor i guess this is the best place to ask. I have a 2002 S-10 with a 4.3 I've done a pretty good amount to it but haven't done anything that touches oil yet. i'll try my best to describe what exatly it's doing. Ok well I installed a variable resistance switch in line with my temp sensor(it's a single cts on the drivers side) in other words i can turn it on and change the truck to any temperature i want it worked fine for the past couple of weeks but recently sense the temp around here has finaly heated up i haven't got it to work right at all and it's throwing up trouble codes about the temp sensor and i'm at a lose and have no idea why it would do this...it worked for 3 weeks if it didn't like it it wouldn't have run right from the begining. I just replaced the switches the today so it's not them i made sure all my conections where still good and their all fine but now for the really messed up thing thats going on when it throws up trouble codes my temp gauge will read 100 even when i know the motor is good and heated up..my idle dosen't change and i put it on my freinds scanner and the truck thinks its actuly at the temp it really is and not what the gauge in the dash is telling me.......holy crap i wrote a book but if anyone can think of anything to help me out it would be so great with that swtich in like that i should have been down to atleast 14.6 or lower so it's very important to me to get it working again thanks