i swapped a COMPLETE 92 tpi engine into a85 truck. the fan works when i run the codes but it never comes on as the truck heats up. i am assuming that i missed a sensor or it is bad. where is the temp sensor for the fans?
thanks
chris

 

i am looking for the PRIMARY fan sensor. that is is the only one that i am using.

 

The ECM turns it on through a relay.

 

Some tpi set ups used two fans. One controled by the ecu and the other controlled by a temp switch in the passenger side head.

 

i am looking for the sensor that controls the ECM. i have a dual fan set up but i am only using the primary.

 

Then you'll be looking for the CTS (Coolant Temperature Sensor) on the front of the intake manifold under the TB. The ECM uses this sensor to detect the engine temperature. Once the temp reaches certain point (I believe it's around 235*F for the TPI), it turns on the primary fan via the relay mentioned above.

Hope this helps.
Lou

 

235, damn that is HOT. does the other one come on sooner?

 

It might be 230*F, I do not remember exactly.
Our cars run at 220 all day so 230 isn't that hot considering.

Lou

 

well i decided to put a hypertech 185 switch in the head. I am going to run it as the primary and the CTS sensor as the back up. that should keep the truck cooler.