I swapped a 4l80 in a 99 truck for a friend and the " ing 0 " fuse blows now. traced it down to circuit 1020, a pink power feed that goes to a few solenods in the transmission. Any tranmission "yodas" want to tell me what to look for?

...Please...

 

Might wanna check the connector.
Unplug the round connector off the trans and see if it still blows it.
If it does then you got a problem in the wiring.
If it doesnt, then maybe a bad 'noid? Or wiring inside the trans?

 

Unpug the main connector, no blow
back out 1020 pink wire, no blow

Just wondering if there were any common shorts to look for, I know I need to drop the pan and inpect.

 

I found someone left the harness loose on a junkyard purchased 4l80e and pinched 1/2 the wires by the pan once

 

Now the really awful part. Dropped the pan to test and inspect... Wires look good, solenoids have resistance reading . (not shorted) and the fuse is not popping with ignition on anymore. Gotta love intermittent electrical issues!

 

Seeing as how this is turning into a blog instead of a thread, I'll continue. I ordered all the componets on that circuit. new harness, tcc solenoid and both shift solenoids. We will see where that gets me...