so I got the p0449 code. we replaced the purge valve and the solenoid canister, still was getting that p0449 code, we had everything hooked up but we hadn't replaced the brackets that held up the tank, then we changed the fuse, number 19 for the evap system 15 amp, it cleared the code. Them when we put the brackets on the tank, the check engine light came back on and it is that p0449 code. Any suggestions on why or what to do next?

 

You have an electrical problem on the EVAP vent solenoid circuit. I'm not sure what the significance of replacing brackets is but, if you replaced the vent solenoid, that'd leave the wiring as the chief suspect.

 

well we had to put back on the brackets that held the fuel tank. I have 2006 uplander 3.5 lt. Do you know where I can get a diagram of the wiring or where Ican get a new wiring harness

 

We're talking about just two wires. Doesn't get any simpler than that. Don't hold me to it but check out the following:

Terminal A, RED/WHT wire, B voltage from I/P fuse block connector C2, terminal 9, (from fuse 19 you changed)
Terminal B, WHT wire, control from PCM connector C1, terminal 10 (PCM grounds this to command the solenoid on)

 

I looked at the connectors and there was an 8 prong one that was all corroded and we had to splice and get a pigtail for the female end and then we are looking at the male end and it is missing 2 prongs and the rest are all corroded and we had to pull out the plastic panel by the door and under the carpet was the only way to get to the male end. Now back to the auto parts store. It is cheaper than buying the parts to dealer and having a mechanic fix it. We are $250 in on parts, but we have replaced the purge valve, the solenoid canister, and now the male and female connectors, but a mechanic or a dealer would be a lot more