Like other transmissions you may have dealt with, the VT40 scan data makes diagnosis much easier. The VT40 does have a line pressure tap as well as scan tool readings from both of the pulley pressure sensors. While we have seen a few issues with the solenoids and/or pressure sensors, the vast majority of the time, the issues are related to actual hydraulic pressure problems. Ratio is not changing when solenoid 2 command values change.Īs you can see, all of the DTCs could have something to do with system pressure, as it affects the pulley positions. P0965 will set if: No speed sensor DTCs are set. Ratio is not changing when solenoid 1 command values change. P0961 will set if: No speed sensor DTCs are set. P0846 will set if: Secondary pulley pressure is not changing as the commanded secondary pulley pressure changes. P0841 will set if: Primary pulley pressure is not changing as the commanded primary pulley pressure changes. Transmission fluid pressure sensor 2 indicates less than 29 psi (201 kpa) while the primary pulley commanded pressure is greater than 72 psi (499 kpa) for one second. P0776 will set if: No speed sensor DTCs are set. Transmission fluid pressure sensor 1 indicates less than 29 psi (201 kpa) while the secondary pulley commanded pressure is greater than 72 psi (499 kpa) for one second. P0746 will set if: No speed sensor DTCs are set. Engine load at least 4%, but the actual ratio does not match the calculated ratio command for the load and RPM. Input and intermediate speed sensors indicate an RPM value of 279 RPM or greater. P0730 will set if: Output speed sensor DTCs are not set. In addition, the customer will likely complain about a lack of power as the unit is not changing ratios. The VT40 has seen a lot of use, especially in the rental car fleet market, so we are now getting some experience with the issues you may encounter.Ĭoncern 1: DTCs set. Most of the units are equipped for start/stop operation. An IMS is used to determine the shifter position for operation. The valve body houses the six (6) VFS pintle-type solenoids and two (2) pressure sensors. The unit utilizes three (3) speed sensors, an input speed sensor, an output speed sensor, and an intermediate speed sensor. The VT40 uses two (2) clutches, one for forward range and one for reverse range. Unlike most CVTs, the VT40 utilizes a chain rather than a belt to provide propulsion. Like other CVT applications, the VT40 varies pulley diameter to change transmission ratios. The VT40 is identified with an RPO of MRG and is the base transmission on some models and an optional transmission for other models. A couple of years ago, I introduced you to the GM VT40 CVT (CVT250), used in multiple applications such as the Chevrolet Malibu, some Chevrolet Trailblazers, and the Buick Encore.
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