Cooling fan low speed not turning on

[vman]

Greetings all! New member to the forum. I bought a 2002 GT (4.6L) a few months ago. Low speed fan is not coming on when engine reaches operating temp, but high speed fan does engage when AC is turned on. I have studied the wiring diagram and think I understand the circuit.

Question, does the 4.6L GT motor have both an ECT sensor (at the intake cross-over) and a CHT sensor (at the cylinder head under the in take manifold) or just an ECT? Asking because the cluster temp gauge is working. If there is a separate CHT sensor, do I have to remove the intake manifold or can I reach it another way?

Common issues I’ve already ruled out including fuses, CCRM, fan motor, and fan resistor. The car has been modded some, possibly tuned, wondering if a tune changed the fan configuration. Is there anyway to check this (I have FORScan)? Also, any other suggestions re potential root cause of the low cooling fan malfunction, much appreciated?!

 

[KRUISR]

I would use Forscan and check and monitor some of the temp sensor reading (I bet there is more than one). I believe you can also monitor if the fan is triggered. Look around at the available parameters and see what ones could be relevant. I haven't used Forscan with a Mustang, but have with my F150 and Escape. Lots of good info in there.

 

[vman]

I answered my initial question from above, there’s only an ECT sensor and I ended up replacing because it was cracked. As a friendly heads up for others on the forum, be sure to get an OEM sensor from Ford…I initially got an aftermarket one from AutoZone and it caused weird behaviors with my temp gauge.

My initial issue (presumably) still remains though, in that the cooling fan doesn’t kick on while driving (unless the AC is running). For reference, my Stang is a 2002 GT (4.6L 2V). A few questions…
Q1. Does anyone know the temp thresholds for the low and high speed fan to engage on a 4.6L 2V? My initial assumption would be not much higher than the thermostat opening temp (192-195), so possibly 200-205)?
Q2. Does anyone know how/if I can read/modify those thresholds ? I connected with FORScan but didn’t see much in the way of config options for the cooling fan thresholds.
Q3. Given that all components in the fan circuit have either been tested or replaced, could a custom tune be at play here and, if so, how do I verify that?