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2010 4.8 elec fans not turning on

2K views 8 replies 3 participants last post by  tazman2010 
#1 ·
Hey guys the electric fans are not coming on and my truck is overheating. I've been looking over the forums and trying to figure it out. my temperature went about 240 and the trans temp to about 215. the coolant overflow bottle is full and the upper and lower radiator hoses were hot as well as the radiator. I opened the hood and the fans weren't on. I checked the fuses and relays and everything looks good. I took the radiator cap off and its full. any ideas on what my problem is?
 
#2 ·
did u manually spin the fans by hand to see if the motors locked up,or u can feel the gritty dragging and u now they gone/going out.
 
#3 ·
I spun them manually and they spin freely I keep my engine bay super clean and cleaned off. I switch the relays around and I can get them to turn on briefly when the AC comes on but at idle the truck will still overheat and the transmission temperature goes up. I get a faint burning plastic smell through the vent when I'm on vent only and the fan is on low speed. I am going to try the clean the radiator from behind with a hose trick. and maybe do a coolant flush and refill. if that doesn't work I guess I'll take it to the stealership. I have 75,000 miles and do mostly highway driving.
 
#5 ·
well guys after five and a half hours at the dealership they said they couldn't duplicate the overheating! now 10 minutes after I leave the dealership and sitting in Taco Bell Drive thru the truck overheated again up to 217 transmission and 240 water temp! so I guess next Friday I will take the truck back to the dealership and sit in the parking lot until it overheats! then I can say come look and the burning smell is still there! but didn't do anything to the truck since they couldn't duplicate the problem! at least I have till May 31st before my warranty runs out on the powertrain, and 2010 up covers the coolant hoses radiator and everything else. up to 2010 the engines are on the cover to the thermostat housing. oh well I wasted 5 hours for next Friday I'm not leaving till it overheats!
 
#9 ·
well on the way to work today the transmission got 249 and the water temp over 240! I roll the window down and didn't hear the fans on. turned on the AC and the fans came on in the temperature went to normal and the transmission went down to 189. so I'm guessing that the electric fans are not coming on with the temperature just with the air conditioning. today must be a sensor that's bad that's not telling the fans to come on when the truck gets hot.
 
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