2005 2wd Tahoe 4.8L (HELP)

[FLORIDA1]

I have a 2005 2wd 4.8L Tahoe that is now just started giving me fits, always been a good ride.
This past weekend my son comes in & says, Dad your Tahoe is running, i'm thinking no way because i'm in the house with keys. So i go outside to learn both my fans are (RUNNING) all on there own, I'm really surprised by this.
So i unlock Tahoe & put key in ignition turn to on & fans stop running, so i start it & let it run awhile & shut it off, fans stay off. So i go back into house knowing something just isn't right. So i start to search online for the causes of this & Everything leads me to the (3) relays under hood & the coolant temp sensor in the driver side head.
Next morning i'm off to O'reilly's for the (3) Relays & the sensor. Change them out for nothing because now not only the same issues but now got another to go with it.
1, With my little hand held scanner it shows me my live operating Temp, truck up to 225 & no fan or fans kick on at all.
2, If i turn the A/C on with truck running, A/C Clutch will kick in & then the fans (Both) come on for a min until it all makes Tahoe run Rough & then die, turn it to heat same thing, runs rough then kill motor.

So, i've cleaned throttle body, installed new Temp sensor, 3 relays under hood, Switch in small A/C line.
Now i'm lost & need all the help i can get with this one.

 

[FLORIDA1]

Anyone see a issue here, if so, what do you see & possibly symptoms?

 

[Fless]

Yes, I see that your ECM is disconnected. Your fans are not gonna run...

Seriously, make sure there are gaskets on those connectors.

 

[OR VietVet]

I see lots of corrosion in a known problem area. The controller that plugs in to may need to be replaced but definitely clean up all those pins on the connector. When put back together and verify fix, seal that connector to controller area to keep the crud/moisture out that caused this problem.

 

[Rocket Man]

Yeah, that corrosion is going to cause all sorts of issues. I’m not sure if you’re going to be able to clean that up without replacing the ECM and possibly the connectors. The connectors can probably be cleaned but the ECM pins, not sure. You can find used ECM’s on EBay but they have to be programmed to your VIN.

 

[FLORIDA1]

Sprayed with electrical cleaner & soft toothbrush, used electrical grease.
All back together, drove for about 25 minutes, Hard driving & regular driving.
Let set & run AC full blast fans on, no more trying to die or rough running.
Turn AC off, fans kick on at 226 runs smooth, cools down to 199 & fans kick off.
No more codes being thrown.
Now just set & watch & see if the fans come on by themselves again.

 

[Rocket Man]

Sprayed with electrical cleaner & soft toothbrush, used electrical grease.
All back together, drove for about 25 minutes, Hard driving & regular driving.
Let set & run AC full blast fans on, no more trying to die or rough running.
Turn AC off, fans kick on at 226 runs smooth, cools down to 199 & fans kick off.
No more codes being thrown.
Now just set & watch & see if the fans come on by themselves again.

Were there o-rings on those connectors? Sometimes they stay inside the cavities of the ECM when the connectors get removed but if they do, you should remove them, reinstall them on the connectors, and reassemble. If they’re missing you could go to a wrecking yard and get some off any 00-06 GM pickup or SUV. They are important in keeping water out. Glad everything is working now, that’s awesome!

 

[FLORIDA1]

Just a big orange O ring around the Blue side & Green of then box

 

[Fless]

Hope it holds! And, yes, the gasket o-rings are cheap enough if you need them. If the old ones are deformed maybe it would be good to get some new ones.

 

[FLORIDA1]

I'm curious what those pins operate. If anyone may know I would really appreciate the info.