Had it with a mechanic who says 80% sure the fuse box is getting hot. Starts cold but only cranks when hot or dies. Bad news they can't find a compatible replacement fuse box for 8 cylinder. So looking for possible causes as to why the fuse box gets hot to try a different approach. They sent my trailblazer back to me. The one code a remember is p1682. Also just before this issue they replaced the ac module because the air stopped blowing. That is why I took it in to them in the first place. Any other things I can do?

 

Well, I have heard of the underhood electrical center going bad. Typical causes are from rodents munching on the wires going to the electrical fuse center from underneath, or cracked/broken copper wire traces inside if the electrical center. You might want to try and find a specialized automotive electrical shop if you can't do the work yourself. I really would not trust a general shop that only deals with routing electrical issues (starters, batteries, windows that do not operate as they should, etc.). You need someone who is not afraid to take the underhood electrical center out of the vehicle to look to see if there are signs of heat/rodent damage in order to tell you "...Yup, darn mice ate through a couple of wires and now they are shorting out..."

Regarding the P1682 DTC, that is telling you there is a problem with the ignition switch circuits. For that I would recommend installing a new ignition switch. Failing ignition switches are a known problem with these vehicles and it is not a question of if it will fail, but when it will fail. Try to purchase a switch from one of the following brands for maximum success - ACDelco/GM Genuine, Standard Motor Products (non T series), BWD (non P series), Delphi, or NAPA Echlin. Stay away from the other brands. Also, I believe that GM non longer sells either the ACDelco or GM Genuine switch for this platform.

Now, if you are really lucky, a new ignition switch MIGHT (key word being MIGHT) solve the underhood electrical center issue. Then again, it might not.

If it turns out that you do need an underhood electrical center (fuse box), try searching car-part.com for one and I bet you'll locate one.

Good Luck!