Jim Dial, Author at Transmission Digest
Understanding lube flow control valves in Toyota/Lexus UA/UB80 transmissions

The Toyota/Lexus UA80 and UB80 transmissions first came out in 2017 in Highlanders and Siennas. The UA80 is used in V6 applications, and the UB80 is paired with four-cylinder versions. They have been called Toyota New Global Architecture type transmissions, and alternately referred to as the “Direct Shift 8AT” eight-speed automatic transmission. This transmission was

Diagnosing AS68RC intermittent pressure switch/linear solenoid performance codes

Intermittent pressure switch codes on vehicles with the Aisin Seiki AS68RC transmission have been very difficult to nail down to one specific cause. The two most common pressure switch codes for this transmission are P0746 clutch pressure control solenoid A or linear solenoid A performance or “Stuck Off,” which also includes pressure switch 1 mechanical

Chrysler ZF8 generations 1 and 2 identification guide

In 2019, some Chrysler/Ram/Jeep applications that utilize the ZF8HP transmission moved to a second-generation unit with a new designation and numerous changes for better performance and durability. Gen. 1 units are classified as 8HP45, 8HP70 and 8HP90; while Gen. 2 are classified as 8HP50, 8HP75 and 8HP95. Internally, the Gen. 2 transmission had numerous hard

Troubleshooting Ford 6R80, 6R140 2-3 shift quality issues

We are all too familiar by now with the numerous band numbers on Ford 6R80 and 6R140 transmissions. We know that — unless you are programming in a new calibration code — it is best to replace a solenoid with the exact same band number as what was taken out of that position on the

Ford 6R80 & 6R140: Troubleshooting timing-related shift issues

As the old saying goes: “timing is truly everything.” Or is it? Either way, we know for sure that this is extremely true in the world of transmissions. Timing problems with clutch apply or with combined clutch apply and clutch release can create all kinds of complaints from flared shifts to harsh shifts to a

Hydraulics Fundamentals: Manual Valves

An understanding of hydraulics is essential for properly diagnosing and repairing transmission problems. This article is one of a series by Sonnax exploring how valves and hydraulic circuits work and what results when they quit functioning correctly.

Hydraulics Fundamentals: Secondary Regulators

Jim Dial discusses the importance of understanding hydraulics when working with transmissions.

Solenoid Differences: Ford 6F35 Gen 1 vs. 2

Looking back on the history of the Ford 6T40, the cousin to the 6F35, we recall a second generation of this transmission coming out in 2012. There were many control-valve changes to this valve body as the pressure switches were eliminated and the top cover of the valve body had damper and spring assemblies added to it to provide miniature shock absorbers to each of the solenoid output circuits.

Understanding 4L80-E Overdrive Clutch Failure

Wintertime typically equals a parking lot full of snowplow trucks. Sometimes they represent repeat business — of the bad kind — but most of the time, new work.

Location and Function of New #8 Checkball for 6L80/90

The 6L80/90 transmission is showing up in shops much more frequently than in the past, as vehicles equipped with this unit get older. Believe it or not, the 6L80 is already 10 years old! As time flies by and we get familiar with rebuilding a specific transmission, we store in our memory more and more details of the disassembly and reassembly of specific items — such as the pump, input drum and valve body — to the point where it becomes second nature. This particular transmission is a pretty easy build. After their third overhaul, most builders would tear down the internal components and dump everything into a basket, run it all through the parts washer and start rebuilding and reassembling after the parts are cleaned.

Dodge 48RE Hydraulic Features Revealed

Dodge 48RE Hydraulic Features Revealed

TASC Force Tips

Author: Jim Dial
Units: 48RE vs. 46/47RE valve bodies
Issue: Differences in pressure curve & TCC clamping

Diagnosing Solenoid Performance Faults in A761, AB60 & A960 6-Speed Units

The Toyota/Lexus A761, AB60 and A960 6-speed transmissions have been showing up in shops more frequently over the last couple of years. Warranties are expiring and people seem to be hanging on to their vehicles longer these days. Even so, there are a number of different issues with these transmissions, including torque-converter clutch failure that is especially chronic with AB60 Tundra applications. Common to all these units is a problem that sticks out a bit more than the others, though: on-off solenoid mechanical fault codes. You’ll see these as P0751 S1 solenoid performance, P0756 S2 solenoid performance, P0761 S3 solenoid performance and P0766 S4 solenoid performance codes.