TCM Archives - Transmission Digest
The Subaru mystery burn

The Subaru TR580 transmission is known for having torque converter clutch solenoid failures. An example of this can be seen in Figures 1 (above) and 2 (below). The solenoid resistance should be between 10 to 13.5 ohms. The resistance right at the solenoid itself on the valve body is close to 38 ohms. And as

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Tips for success with the GM transmission fast learn process

This article is about failure, something we all experience from time to time. If you are attempting to perform a fast learn process on a GM eight-, nine-, or 10-speed transmission, you may have that temporary feeling of failure, as this process can bring on frustration quickly. Let’s talk about what the fast learn process

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Land Rover LR3 ZF6HP26 no start after overhaul

The complaint A 2006 Land Rover LR3 equipped with the ZF6HP26 transmission has a post-overhaul complaint of a no-start condition. Part of the transmission overhaul process included the replacement of the mechatronic unit. The cause The mechatronic unit that was purchased from a parts distributor and installed was for a Ford 6R60 transmission (figure 7)

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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

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Another needle in a haystack: Locating wiring problems

Paul Loch from Certified Transmission wrote a very good and detailed article for Transmission Digest in the March 2022 issue entitled “A Needle in a Haystack – Finding and Diagnosing Intermittent Problems.” The vehicle used for this article was a 2013 Ram 3500 6.7L equipped with a 68RFE transmission. Well worth the read. ATSG encountered

TCM trouble and the importance of being certain about parts replacement

It’s a tale as old as time. A vehicle comes in and, despite having been recently repaired by another shop, the vehicle owner’s concern is still present. In the case of this story, the vehicle came from a local shop we work closely with. The truck in question is a 66,000-mile 2006 Chevrolet Silverado 2500

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Solving electronic control problems in today’s automatic transmissions

Special tools are often needed when diagnosing transmission problems and overhauling units.

Japanese CVT no-move conditions: Failsafe or defective TCM?

The Japanese Automatic Transmission Company produces a continuously variable transmission (CVT) known as the JF016/17E, which has been fitted behind 2.0L to 3.5L engines worldwide. Here in the United States, there is a light version called the CVT-8LT for 4 cylinder applications (JF016E) and a heavier version called the CVT-8HT for V-6 applications (JF017E). Nissan

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Having a fit with a Honda Fit

A Honda Fit utilizing a GTAA continuously variable transmission will set a DTC after reaching about 30 miles per hour. When a scan tool is used to pull the code or codes set, a U0401-68 code appears in the scan tool with the explanation of it being a TCM failure. If a tech uses the

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The diagnostic value of the scope

There was a time in my career when replacing a computer was touch and go. I always tried to do my due diligence and eliminate everything else as a possible cause before replacing the computer, but sometimes that wasn’t enough, and I would miss something along the way. That was long before I learned how

2016 Nissan Altima: What to do with a defective TCM

Nissan vehicles that produce Judder codes DTC P17F0 and/or DTC P17F1 in many cases will be a defective TCM. One sure way to know is to document and clear all codes. Then, keep the ignition on for a bit without the engine running. If the code returns, a defective TCM has been confirmed requiring a

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Transmission control software: Know your terminology

When it comes to a post-rebuild adjustment of transmission control software, the terms flashing, re-flashing, programming, reprogramming and tuning often get used interchangeably. That said, each of these has a specific meaning and is used to address specific situations. To understand some of these terms we would have to break down the controller into three

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