2005 GMC Yukon XL cooling fans run continously

[PMARTIN441]

Hello,

 

I have a 2005 Yukon XL it has 254,000 miles on it and after running around all day, we came home and the cooling fans would not cut off. I pulled the fuse and of course they turned off. The first thing I did was I replaced the relay located under the fuse box under the hood. Didn't fix it. So I turned to the internet and several forums point to the PCM. Just recently our heated seats quit working and the check engine light has been on for quiet a awhile. Now after only sitting a day I started it to move it and the engine started idling a little rough and it started smoking from the tailpipe. Any Ideas? Also if I do replace the PCM will I need to take it somewhere to get it programmed or will it be a pull and play kinda thing?

[PMARTIN441]

Ok here is an update. I had a code for the PCM and a code for a crankshaft position sensor. After looking at the PCM I found dirty contacts on the blue wiring harness. I cleaned the harness and the PCM contacts and the problem disappeared. However I think it killed my battery. I have a 4 year old battery and now it has a sluggish start. So I put the battery charger on it and after it being on charge for a while the stupid fans turned on again. So every time i disconnect the battery and spray EC cleaner on the connections the problem goes away for a day or so only to return again. So I am thinking a new battery and a new PCM?

[PMARTIN441]

Ok so I replaced the relay, I replaced the PCM and the cooling fans come on about 10 mins after the truck is parked. I am at a loss as to what is wrong.... Any ideas???? Anybody

[txab]

Read the stored codes first