Diagnosing Transmission Problems

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Shift Pointers: A 10R140 with a classic drivability complaint

A 2021 F-350 6.7L Super Duty using the 10R140 beast of a transmission recently came into Precision Auto Repair not upshifting when pulling a load only. On light throttle it would upshift, but not as high as tenth gear. Once the throttle was depressed it would downshift and no longer upshift. It displayed similar symptoms

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6R80 whirring noise: TCC slip or engine surge?

About a month ago, we at Certified Transmission received a 2015 Ford Expedition 4WD at the shop. It was equipped with a 3.5L Turbo V6 engine and a 6R80 transmission. The complaint read, “RPMs fluctuate up and down and there is a whirring noise.” The vehicle was brought to us by one of our wholesale

The torque converter can of worms: Lockup and aftermarket programming

Lockup torque converters have been around now for some time. They came into production around the time when fuel mileage demands were put into effect by the government, and the auto manufacturers needed to do something to better connect the fluid coupling (torque converter) of the automatic transmission to the motor. By doing this, OEMs

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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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Shift Pointers: Where’s that fluid leak coming from?

A 2016 Honda CRV 2.4L (Figure 1), using a BLJA CVT 4WD transmission (Figure 2) comes in to a shop with a customer complaint of a leak. Before anyone checked fluid levels, the vehicle was hoisted up for a look. A visual inspection revealed a leak coming from between the transmission and the engine. The

Multitasking: Sorting out multiple issues with the same vehicle

While it’s common for a customer to bring us a vehicle with a single, specific complaint, we often find more than one problem when getting into the diagnosis of their original concern. The owner only knows one thing; they want the vehicle to run and operate properly. It’s our responsibility to identify and execute a

Chrysler RH/RE late shifts and high pressure

You may find that these transmissions have a late 1-2 and 2-3 shifts along with high TV/line pressure.

Ford 6R80 shift solenoid ‘E’ resistance change: How to tell the difference

The lower resistance and higher resistance solenoids are not interchangeable.

Allison 1000 geartrain bind-up

When the torque converter housing is bolted to the transmission case in an Allison 1000, the geartrain is locked and will not rotate.

How to get around non-serviceable GM 6T70/75 self-tapping pump screws

General Motors designed the 6T70/75 transmission fluid pump to be a non-serviceable component.

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Watch out for high pressure in GM 8L45, 8L90 valve bodies

Hey now! Oh boy, do I have a fun failure to share with you and warn you about today! Have you encountered a crack in the worm tracks in your GM 8L45 and 8L90 valve bodies (as seen in Figure 1, above)?  Sonnax has, and wow, is it frustrating. Once cracked, there is no way

Ford 8F24 mechanical diode failure

Mechanical diode failure in automatic transmissions is not uncommon. As far back as the AODE/4R70 shops have seen this type of failure. In April 2022 an article was published in Transmission Digest called, “The ins and outs of the Hydraulic Selectable One-Way Clutch (SOWC).” This article provided photos of the type of damage this style

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