05 Sierra Overheating Fan Issues?

bryriden · July 2, 2009

hey guys my 05 5.3 sierra has overheated on me twice lately, it has dual electric fans factory, it is not loosing any fluid it seems as if the fans are coming on when needed if the ac is on both fans run but when off nothing, at 210,,,, today it overheated with the ac on the ac got hot looked at the temp and it was up , i pulled over and cut the ac off and back on and the truck cooled down to 210, it seems to be and intermittent problem, anyone had any similar issues maybe a temp sensor,, low pressure switch ???? help

redvett · July 2, 2009

Cooling fan is controlled by the PCM Have you checked the coolant level & have you done a flush & fill? Your truck is four years old its time.

alwcurlz · July 2, 2009

Sounds like you have a faulty/defective thermostat. I'll bank on that. The thermostat is built into your water pump as well. I think they run about $70 for the water pump/thermostat. I'd get it replaced! If nothing else, it'll cost you $70 rather than the cost of a new motor.

bryriden · July 4, 2009

yes but there has to be a temp sensor that sends a signal to the pcm ??

Cooling fan is controlled by the PCM Have you checked the coolant level & have you done a flush & fill? Your truck is four years old its time.

alwcurlz · July 4, 2009

yes but there has to be a temp sensor that sends a signal to the pcm ??
Cooling fan is controlled by the PCM Have you checked the coolant level & have you done a flush & fill? Your truck is four years old its time.

You know, come to mention that, my brother's 01 Silverado had some rough engine running problems and we accidentally discovered there was a bad wire right near the water temp sensor. The auto parts store had just the connector and wire we needed. I guess it may be a common problem if they have them on hand! The temp sensor is right behind the power steering pump in the left engine head. Just touching the wire would make his truck shudder and it was stalling sometimes. Kinda wild, but, the truck would shut off if it was disconnected! Even though it's possibly not related, may want to check that wire and replace the $12 sensor that goes there!

redvett · July 4, 2009

The CTS sensor is the same for the PCM & the guages.

moboy · July 4, 2009

hey guys my 05 5.3 sierra has overheated on me twice lately, it has dual electric fans factory, it is not loosing any fluid it seems as if the fans are coming on when needed if the ac is on both fans run but when off nothing, at 210,,,, today it overheated with the ac on the ac got hot looked at the temp and it was up , i pulled over and cut the ac off and back on and the truck cooled down to 210, it seems to be and intermittent problem, anyone had any similar issues maybe a temp sensor,, low pressure switch ???? help

My '05 crew started doing the same thing and then started loosing coolant. The truck sat in the garage most of the time as I drove my old cherokee to work. The coolant loss was my biggest concern but when the truck started blowing blue smoke at startup I really got concerned . I then noticed the oil on the dipstick looked cooked and I change the oil every three thousand miles. I read on the forum about cracked heads and sludge buildup do to a steam issue under the valve covers caused by the stress fractures in the heads. Anyway the '05 was sold and an '09 crew replaced it. I told the guy I sold the truck to about the issue and he thought I was dreaming as he didn't see any issues with it for the first week he owned it.....believe it went to the auction last week!

don0442 · July 17, 2009

I had a similar problem....would heat up in traffic with the a/c off, but turn it on, and the temp would go back down.

Bottom line...take a lazer temp reading at the edges of the rad with it running temp, and then check the center. I have the same truck, and the radiator was plugged.