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Showing results for tags '2006 GMC Sierra 5.3 XLT'.
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Cooling Fans not Coming on
Jake Camacho posted a topic in Gen III and IV Small Block & DrivetrainFellas and Gals! I am having a problem with my cooling fans not coming on my 2006 GMC Sierra, 5.3. I can force them on by running the A/C constantly. But if the A/C isn’t on, the fans won’t come on till the truck reaches almost 230 degrees F, which I’m on the road to cracking a head at the temp. I’ve already replaced the fans, thermostat, engine temp sensor, checked to make sure I’ve got good water flow through my radiator, I’ve replaced all three cooling fan relays and I’ve checked the wiring harness. The fans will come on when I reach in there and manually unplug the harness from the temp sensor while the truck is running and it sometimes will throw a code after that. The only thing I can imagine may be happening is the CPU is not sending the ground signal to command the fans to come on when the engine reaches the appropriate temp (≈ 202, without the A/C being on). Has anyone ever experienced the CPU messing up and not send a ground signal to the system, what am I missing? S.O.S. PLEASE SEND HELP!!