Transmission Digest

12/29/2025

This case involves a somewhat misleading trouble code and symptom, and the solution may save someone else time in the bay. Read our latest R&R Tech column here:

From time to time, we run into drivability issues that seem straightforward at first glance but end up leading us down a very different diagnostic path. Within our own shops, we do a good job sharing these experiences with one another, but it’s equally valuable to share them with the broader indus...

12/23/2025

The interactive and easy-to-use digital edition of Transmission Digest’s December issue is ready for viewing now. Take a look here:

The interactive and easy-to-use December digital edition of Transmission Digest is ready for viewing now online.

12/22/2025

It's time to vote in our annual Top 20 Powertrain Products contest! View the candidates and vote here: bit.ly/TD-Top-20-2026

12/19/2025

Some 2020–2023 GM 3500HD series trucks with 10L1000 transmissions may experience early TCC application or a condition in which the engine drags when coming to a stop. The most common complaint we see is the engine drag down coming to a stop.

Read more in our latest TASC Force Tips article:

Some 2020–2023 GM 3500HD series trucks with 10L1000 transmissions may experience early TCC application or a condition in which the engine drags when coming to a stop. Figure 1 (above) illustrates normal TCC operation on a 2022 Denali diesel application. Note that TCC applies right near the 4-5 ups...

12/17/2025

A recent webinar hosted by Andrew Markel, our director of technical content, and Jim Dial, product line manager at Sonnax, spent an hour discussing 10-speed transmissions from Ford and GM: what sets 10-speeds apart, their history, the similarities and differences between the Ford and GM models, and much more. From that conversation, we’ve compiled a checklist of what to look for when a 10-speed transmission with a potential issue comes into your shop—from the diagnosis and test drive to common issues to TSBs and recalls.

Here are ten steps for diagnosing and repairing 10-speed transmissions:

What to look for when a 10-speed transmission with a potential issue comes into your shop—from the diagnosis to the test drive.

12/15/2025

The 8L90 pump chain is known to get elongated. The question that often comes up is, “What is the specification for checking this chain?”

Read our latest Technically Speaking column for more information:

The 8L90 pump chain is known to get elongated. The question that often comes up is, “What is the specification for checking this chain?”

12/12/2025

Today, Builder’s Bench co-host Rino Partipilo shares a story from a shop that called ATSG with a Ford 10R80 no-move condition—it was barely moving either in forward or reverse.

There are fixes for this besides replacing the pump. Take a look at the video for more information:

Today, Builder's Bench co-host Rino Partipilo shares a story from a shop that called ATSG with a Ford 10R80 no-move condition—it was barely moving either in ...

12/10/2025

C & M Gearworks serves multiple purposes and customer bases. The largest segment served is the company’s role as a distributor of differential and axle parts. And then there’s the curios collection, which is practically an on-site museum.

Read their story here:

C&M Gear Works serves multiple purposes and customer bases. The largest is as a distributor of differential and axle parts.

12/08/2025

Our guest on this episode of Powertrain Perspective is Scott Schleck, owner of Midwest Transmission Center. Based in Zumbrota, Minnesota, Midwest Transmission Center has a remanufacturing facility that produces full manual transmission units. The company offers transmissions, transfer cases, clutches, differentials, new and used parts and accessories.

Watch our conversation here:

Our guest on this episode of Powertrain Perspective is Scott Schleck, owner of Midwest Transmission Center.Based in Zumbrota, Minnesota, Midwest Transmission...

12/05/2025

Ford saving a GM 9T50? It's a true story, and you can read about it here:

A 2018 Equinox with the GM 9T50 transmission came into the shop with a sever bind going into second gear preventing any further upshifts.

12/03/2025

Believing the issue to be internal hydraulic pressure loss, the shop opted to replace the entire transmission. However, after installation, the same DTC reappeared—and now the transmission had no reverse gear. Further testing led the shop to conclude that the ECM was not providing voltage to the solenoid. They replaced and programmed a new ECM, but the problem persisted: same code, still no reverse. That’s when I got the call.

Read Randy Peterson's full account of what happened here:

When the vehicle arrived, I confirmed the presence of DTC P2720 and verified that Reverse was inoperative.

12/01/2025

The internal wiring harness for the GM 8L90 transmission has undergone a variety of changes from its launch in 2014 to the present. Let's go through them all, and why they matter to you:

The internal wiring harness for the GM 8L90 transmission has undergone a variety of changes from its launch in 2014 to the present.