05 LS Overheating - Maintenance and Repair Forum

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05 LS Overheating
Thursday, February 16, 2017 1:23 PM
--- 2005 LS w/ 2.2-EcoTech

so, my 05-LS is overheating, only does it when idling or driving at low speeds....
I literally JUST replaced the thermostat (plus drain & refill) like 3 hours ago & still having the issue.

When driving on the highway, it stays below 180 degrees and never overheats AT ALL... not even a little bit.
But, when I'm peddling around town & staying under 40, plus stop-n-go traffic, it starts over heating.

The fan engages with the A/C, but, doesn't seem to without it.
It will reach 2 lines over the 195 (center) mark, after idling for about 10-15 minutes, but if slow cruising through town, it does it much quicker.
And, when its warm out, like today (73 degrees) this happens really quick, versus when its cold out, it hardly does it at all...

anyone have any ideas, or experience with this?


DexCool coolant level is full, no sediment, isn't burning, or anything else...
Oil levels too are fine and not burning either.
Trans fluid is clean & full as well.

Re: 05 LS Overheating
Wednesday, March 01, 2017 5:14 PM
If you are hitting 200 that fan should be kicking on. If it is not then you have an issue with your fan control circuit somewhere. I wish I had a schematic in front of me but I don't at the moment, sorry, don't have that hard drive handy at the moment. A Haynes/Chiltons manual should have that schematic in it.

Re: 05 LS Overheating
Saturday, March 04, 2017 11:09 AM
well the fan kicks on with the A/C. but really otherwise...

got the thermostat done, and it seems to have helped a bit... but is still getting warm. but never seems to clear 225-230... and the fans never come on.

maybe i need to replace some fuses?
Re: 05 LS Overheating
Sunday, March 19, 2017 7:34 AM
If the fan kicks on with the A/C, it's not a fuse. The t-stat sends a signal directly to the ecm, the ecm sends a signal to a relay (under the hood), the relay activates and fan spins up. For A/C activation, A/C is turned on, ecm sends signal to same relay, relay activates and fan spins up. If you have a scanner/monitor available, plug it in and monitor the signal from the t-stat to make sure your gauge is indicating the correct temp.

Re: 05 LS Overheating
Monday, March 20, 2017 7:29 PM
Temp sensor could be acting up.
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