Hey Scotty, thanks for taking our questions and giving honest answers. I have a 2008 GMC Sierra with a 4.3 L V6 engine (95K miles). Anytime I drive over 55 MPH the truck will display a message that the engine is too hot and the A/C has been turned off; the temperature gauge will also drop to 0 and the truck will blow hot air. The only solution I have found is to disconnect the battery to reset the computer and the truck will be back to normal immediately. Could you please outline a few steps I could take to correct the problem permanently?
Jason
I would find somebody with an OBD reader and use it to find out the engine temperature it is reporting. If it really is overheating, then standard troubleshooting applies. Make sure that radiator fan is coming on full.
https://www.youtube.com/watch?v=evpaTW2WJ5Y
Does the engine also overheat when you go lower speeds?
@yaser
No, the problem only happens at higher speeds. However, I don't think the engine is actually overheating. If I pull over, disconnect the battery, reset the computer by touching the two battery cables, and restart the truck the problem is fixed. I'm wondering if the problem is in the electrical system or a sensor.
Maybe the coolant temperature sensor is not functioning properly.
If this is the one with a cylinder head temp sensor it will cut the power to the engine if it senses overheating. Its abbreviation is CHTS and will make all kinds of issues. Might check the coolant temp sensor although I'm not sure if it reads to high it will cause the car to shut off.