donbrew I verified through a ACDelco site that the 60 ohms is a desired value.

https://www.techconnectcanada.com/bl...d-lan-concerns


But if I am still misunderstanding you, please advise. Like I admitted earlier, I am outmatched and have no idea what to look at next.

 

I got my good/bad mixed up edited now.

If you have 60 then you shouldn't have the U codes. First you say you got codes, then you say no communication problems U codes mean there is a problem on the CAN bus, could be no power to a module.

Now I am reading more of the OP, sorry it is long and I bore easily. The power train relay supplies power to fuse 33, 45 and 41; the hot side of the relay is always hot. So, jumping 30 and 87 on the relay should do something. That would explain the 2 U codes. 30 should be always hot.

 

Thanks so much and no need to apologize for anything.

If I am understanding you, I need to jumper those on the RUN/CRANK relay correct? And that should at least cause a change that is noticeable?

 

The pwr trn relay. Position 26 under hood.
fuse 43 is fed by the run crank relay (always hot relay also)

 

I will try it and update. Thanks

 

Well I tried. No change. But I did learn something from the experiment. There is no voltage present at any of the terminals to that relay. I checked a few others and same situation. I removed the power cable to the fuse box and scrubbed with sandpaper to insure all corrosion was removed. I thought possibly could cause the random complete power cutout.The vehicle is now in Vegas but history report from GM shows been in New York most its life. Lot of rust and corrosion.

I am thankful for all the replies.

 

If the main lug on the box is hot and there is no power in the box you need to take the box apart or get a new one. They have been known to self destruct internally.

 

Well there is power in the box to all the fuses except for 33 and 41. There is missing voltage to several relays though.

If we are speaking the same language, then we agree it "could" be the box. I can replace it if you think it's worth trying.

 

Depends on how easy you want to go ,it comes apart pretty easily.\\

 

pin 30 on most relays is hot always. at least the run/crank, pwr trn and fuel pump. As far as I know that comes directly from the lug which goes directly to the battery.