The wiring diagram for my Trailhawk thinks there is a radiator fan "enable" relay in the Power Distribution/fuse/relay Center. The 12vdc output of this relay enables the fan control module on my dual fan to manage operation of the fan in accordance with commands separately sent to it by the Powertrain Control Module. A problem has developed where the fan does not turn on when the AC comes on OR when coolant temperature approaches 240F. The expected 12vdc from this relay does not appear at the input to the fan control module which is mounted on the dual fan assembly. Good wiring is verified from the PDC to the Fan Control Module. I do not find a relay in the PDC which is identified as "fan" or "radiator". Can anyone tell me the K number for this relay and what type relay it is? If not, i guess i'll substitute the ground connection normally supplied by the PCM with one supplied by me and listen for clicks from the PDC.

UPDATE: The "listen for clicks" method worked. The relay is embedded between layers of the the circuit boards in the PDC. Not visible and not the plug-in type. And so the fan started running when the relay coil got the ground connection it needed to operate. Now, why is the PCM not supplying that ground as it once did? We shall see.

 

Hello, can you tell me exactly how to solve this problem? Disassemble the fuse block or directly connect the ground to the fan block?