Diagnosing Transmission Problems
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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How to service Volkswagen, Audi dual clutch transmissions

You may have heard the term “DSG” or “DCT” being used when referring to Volkswagen/Audi transmissions. DSG, which stands for “direct shift gearbox,” is the marketing term used by VW/Audi for their dual-clutch transmission (DCT). In simple terms, this type of transmission is composed of two separate manual transmissions inside a single case, each one

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

GM 10L80: A new kind of pump noise

How quickly time passes by. The GM 10L80/90 transmissions began production in 2017, meaning that we’re closing in on six years of this transmission being on the road. Many who work in the dealerships have become privy to the immediate failures that occur in this unit. And now, with some of these transmissions coming out

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Chrysler 948TE: It’s a doggy dog transmission

The Chrysler 948TE transmission (seen in the above image) stands out for its unique use of two dog clutches: dog clutch A and dog clutch F. Dog clutch A (Figure 1) is used to drive an annulus/sun gear while dog clutch F (Figure 2) is used to hold a double sun gear stationary. In a

Ford 6R140: Identifying unique torque converter features and avoiding application pitfalls

The Ford 6R140 was introduced in 2010 (for 2011 model year trucks) as a six-speed used in Super Duty gas- and diesel-powered applications. Today, these units are in high-value, hard-working trucks at the peak of the repair cycle. Aftermarket programming (especially with the diesel variants) is pulling additional power from the engines, putting further loads

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Common failures on the GM AW55-50SN

GM’s AW55-50SN, otherwise known as the AF33 transmission (figure 1, above), is known for its placement in vehicles including the Chevrolet Equinox and Captiva, the Pontiac Torrent and the Saturn Vue. Versions of this transmission can also be found in SAAB, Volvo and Nissan vehicles. This unit began being produced in 2000 and ended production

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What to do when a GM 6T40 BAS Hybrid loses line pressure

After overhaul, a GM vehicle equipped with the 6T40 BAS Hybrid transmission has a complaint of little or no movement.

Diagnosing diagnostic codes

The codes being diagnosed in this article are: P0507: Idle speed performance higher than expected P0871: OD pressure switch rationality P0934: Line pressure sensor circuit low A 2006 Jeep Commander using a 545RFE transmission arrived at our shop from an independent muffler and general repair facility with three codes: P0507, P0871 and P0934. The codes

Keep an eye out for 6L80/90 defective oil pumps

The complaint After replacing the pump assembly in a 6L80/90 transmission with a new GM pump the vehicle returns with symptoms that would appear to be caused by a low fluid condition: it falls out of gear at a stop and has low line pressure. Upon further inspection the sump filter, which was also a

Avoiding 4L60-E harsh shifts and engagements

The complaint The complaints are harsh engagements and shifts. The scan tool data reveals that there is no amperage command to the EPC solenoid therefor the line pressure is at maximum. There are no transmission codes stored, there are lean codes stored in the ECM. The ABS or the VSC (vehicle stability control) lights may