My LS1 has been sitting for 3 years and I just finally fixed it and plan on driving it again. What kind of maintenance should be done before I start driving again? In those 3 years I would turn the engine on once in a while and let it warm up. My only issue right now are the coolant fans wont turn on. I've already checked the fuses and they're fine.

 

What did you fix on it after the 3 years of sitting?
How hot does the gauge say it's getting?
Does the radiator get warm/hot?
Is the SES/check engine light on?

Maybe a stuck thermostat. Wouldn't hurt to change it out any way.
Fresh oil and filter is a must.
Seafoam in the gas would be a good idea.
Don't beat on it until its been warmed up and drivin for a bit. I would take it down the highway for a nice long trip with the fresh oil/gas.

 

change all fluids and fix anything you know is wrong and be ready to have other things replaced that have been worn out from sitting.

 

All I've done to it was get the frame straightened out, body work, and paint. The gauge will get to right under the 210 mark, but the most I've driven it was about three miles. I can turn on the fans manually with hptuners.

 

The engine light isn't on but its throwing these codes P0480,P0481, C0121, B0017, B0018, B0024, B0026, B0051, B1000, U1000, U1016.

 

I checked both fan relays by swapping them with the starter relay and both seem to work.

 

You will have to find out what all of the codes are for and start fixing/deleting the systems that cause them.

 

both p codes are for the fan relays, the other codes are for the airbags which I'm not really concerned about.

 

Seafoam it (Mopar Combustion Chamber Cleaner works better, if you can find it), change air filter, clean the maf, new PCV (I recommend the orifice-type truck one), good oil flush, change plugs (possibly wires, too), change thermostat.

Do everything in that order, and she should be running like a top. Then, just start troubleshooting systems.