87tpita

Ive got a 94 LT1 and Ive read they normally run @220 witch is to hot for my taste. On my 87 TA there a simple rad fan sensor on the pass head that I changed to a 180 temp for fan operation. Is this mod the same for the LT1 and will it have any negative affects on the way the fuel n air delivery system works? thanks

Green96Z

The fans are controlled by the PCM, and it takes the coolant temp from a sensor in the water pump. They are programmed to run so hot from the factory to lower emissions. You can switch to a 160 degree thermostat, run a manual fan switch (either buy one or wire it yourself), or have the PCM reprogrammed to turn on the fans sooner.

Shoebox has a write up on wiring your own fan switch:

http://shbox.com/1/fan_sw_diagram1.jpg

87tpita

I just found this at summit, it seems like the same deal as what I did to my 87ta and it worked perfect. From what I understand the signal the pcm gets from the oe switch at @220 is changed to @195 with this. Basically plug n play. I maybe wrong but this is my understanding.
http://store.summitracing.com/partde...5&autoview=sku

shoebox

That will work, but it works by overriding the PCMs signal to turn the fan on. The factory sensor only tells the PCM the temperature. The PCM is what tells the fans to come on. That's why it takes programming to change the fan ON temp.
The JET switch merely applies a ground to the fan relays at the temp stated to run the fans.

87tpita

thats how the factory sensor works correct? the sensor sends a ground witch tells the pcm its at the preset temp @220. Are there any downsides to the jet switch you know of? thanks

shoebox

No, the PCM determines temperature by changes in resistance fed to it by the sensor. The preset ON temp of the fans (226°) is in the PCM programming, not the sensor.
The JET switch is meant to work with the f-body LT1 electrical harness. It is inserted into the harness with the plug-in connectors. AFAIK, people have had no problems with it.