I walk the view through electrical/electronic testing and diagnosis via a multi-meter for 4L80E transmissions while the transmission is still in the vehicle or otherwise fully assembled. I also give an overview and demonstrate test procedures on he pressure switch manifold assembly, which has to be tested directly when the transmission pan is removed.

The video has tables and diagrams to aid the tester during the process and should give anyone looking to diagnose or troubleshoot a good understanding of what to do and how to do it. It's also helpful for anyone looking to purchase a good used transmission that has a multimeter with them when checking out 4L80Es for sale at junk yards, swap meets or on Craigslist.

4L80E ATSG Manual: file:///Users/nicholasnuciforo/Downloads/4L80E%20ATSG.pdf

Converting 1991-1992 valve body and spacer plate to work with 1993/94+ non-vented EPC produced by Borg Warner: https://res.cloudinary.com/transgo/wb...

Tech Notes: ATSG states the wiring harness changed in 1993; torque compensator valve eliminated after 1993; however, if you have a 1991-1993 model year unit that has the earlier harness/VB, you can install a Rosta harness, part number 34446AK (works on all years 1991-2003), updated BW non-vented solenoid and adapt the VB and plate to work with the updated EPC (See Transgo link for instructions below). Valve bodies that use the initial vented electronic pressure control solenoid (EPC), produced by Bosch, will need to be adapted to work with the updated Borg Warner/Holly EPC. See page 5 of Transgo's SK-4L80E shift kit instructions on how to do this procedure: https://res.cloudinary.com/transgo/wb...