question about CTS and fan switch

[MusclecarJohn]

Hey everyone, I was searching this forum and read about the fan switch that is threaded in the right or left side head, I believe it's GM#3053190
I think it supposed to lower cooling fan(s) "on" temp
does anyone know if this lower temp fan switch is sill availabe thru the dealer or other sources? I would like my cooling fan(s) to come on sooner if possible, also, as we're changing out the water pump and opti and all, do you guys think I should get a new CTS as well? and is there such a thing as a lower temp CTS?

 

[toptechx6]

LT1's use the CTS in the water pump housing for the temperature signal for fan control, but the ECM actually controls the fan relays using the Quad Driver Module. The temp sender in the rt. cylinder head is for the analog gauge in the cluster.
There are aftermarket fan switches that can be used to control the temperature the fan comes on, they splice into the relay control wire from the ECM, the switch itself screws into the left cylinder head between cylinders 1 and 3 by removing the existing plug in that location.
If you use such a switch the ECM will notice the fan is on when not commanded and will set a code 28 for Quad Driver Module circuit #3, but the code will NOT illuminate the MIL, just understand you will see the code if you check after installing the switch.
A better way is to have your ECM reprogrammed to lower the fan on/off temp, you may even gain a few horsepower by having the spark advance set for premium fuel at the same time, hope that helps.

 

[MusclecarJohn]

Thanks toptechx6, I didn't know for sure, I think I'll just leave it as it is though
I don't wanna set any codes and don't wanna mess with the ecm, but I guess LT1s, and L98s run a little on the hot end

 

[toptechx6]

From the factory the ECM is calibrated to turn the fan on at 228*, by then the analog gauge will be in the "scary" range for us old school guys :L.
The owners manual says to use the digital display for the most accurate reading, but the newer engines do run hotter for improved emission control and fuel economy.
If your fan comes on around 228 by the digital gauge and the temperature drops when it does you are fine, if not make sure you inspect the radiator for debris, common for it to collect there and that will cause higher than normal engine temps.

 

[MusclecarJohn]

Thanks for all of the good info toptech, It's guys like you that make the rest of us more learnt :L