Join Date: Sep 2016
Location: Tellico Plains, TN
My 2013 developed problems with the radiator cooling fan last summer. The fan would start at 194° run for about 20 seconds and shut off for about 2 minutes and then cycle on again for another 20 seconds. This caused serious overheating problems. My dealer was not able to solve the problem. If this is what you are seeing, at least you have company.
Everything you are looking for is located under the center council where the hydraulic control is located. The fan fuse is a 40a located in it's own holder in the back left of the electronics pan. The fan relay is located right next to the fuse. To the relay there is a 40a circuit breaker between the battery and relay. The coolant sensor is wired to the ECM then to the ECM relay which triggers the cooling Fan relay.
So what is wrong becomes a complicated question with a lot of chasing of the signal thru 4 devices on the 20a signal side. If your fan comes on at 194° and runs until 182° coolant temperature is reached while in a low idle range only to cycle short ons and long offs at high load and rpm it is called an intermittent failure and the dealer is not going to find the problem with the service procedure they use.
Lift the bed, turn the key off, remove the wiring connector from the coolant sensor, turn the key on(do not start engine), does the fan motor run and the check engine warning light up in a few seconds? Bad coolant sensor or connections. The rest of the fan circuit is good(so they say).
Does the fan motor run slower than usual? Bad motor or weak ground.
Does your dash display show coolant temps correctly above 194°, hot warning light at 230°? Then your sensor is working, signal is getting to the brain box and going from that side of the box to the dash.
That leaves us with 3 possible errors we must check when the engine is running and above 194°. This is not the ideal situation. We already know that the system works at 197° and below. We have a brain box, ECM Relay and a Fan Relay to deal with.
Hopefully replacing the Fan relay and the ECM relay fix the problem. If not a new Brain box or an override option must be wired.