My 305 fan running constant after and maybe b4 i replaced the rad and 180` thermo. Aloso rebuilt the top end on a new long block. Any ideas? The temp guage doesnt seem to move either. Before it was running over 220' witch was causing detonation due to over heat cond. No fault codes atm...

 

If This is tpi and the fan is running constantly the relay is bad or the ecm is bad or you have a wiring issue like the relay wire going to the ecm being grounded or the incorrect memcal is in the ecm. If this is a ccc the ecm is not controlled bye the ecm the relay is controlled bye the single wire cts being grounded.

 

It is TPI. ECM is ok. Any idea where the relay is?

 

I guess you have already checked c1 for being grounded than.

 

The ecm pin d11 is n/c a/c fan switch if this circuit is open or the incorrect memcal is installed in the ecm the fan will be on at all times.

 

What installs memcal in the ECM the CTS? Replaced the fan relay. Fan still on when engine cold. Fan doesnt run with just ignition hot like it sposed to. Also i heard ECM may be bad if yhis were the case the car would run like crap no?

 

The memcal is the engine calibration in the ecm, The ecm can have the driver bad for the fan control and still run fine. The ecm controls the trigger ground side of the relay based on the input from the ect and the memcal calibration. When the car reaches 35 mph based off of the vss input the fan will shut off unless needed. When the engine reaches 226f in most calibrations the ecm grounds the trigger side of the relay allowing power to go to the fan. You need to start doing so electrical testing and start with checking the ecm controlled relay ground wire. If the a/c pressure switch is grounded the fan will also be commanded on.