GM’s 4T45E Transmissions: The Good, Bad And The Ugly

Posted by on Tuesday, February 12th, 2013

The 4T45E is an automatic transmission made by General motors. The “4” stands for four speeds, the “T” stands for Trans-axle, the “45” means that it can be used in a vehicle weighting up to 4500 lbs and the “E” stands for electronic. Because this transmission was used extensively throughout the entire GM line up of brands, it is wise that as a shop owner, or car junkie, that you are made aware of some of the short comings and oddities of this transmission.


Nice internal view of the 4T45E transmission


Because many different gear ratios were used to determine the final gear ratio in the trans-axle, much care should be taken when replacing the transmission. A total of four different gear ratios were available and installing the wrong one will play havoc with the computer and all the sensors on the vehicle.

The 4T45E does not use a dipstick to allow the measurement of the transmission fluid level.  Instead it has a fill plug on the side of transmission (like a manual transmission).  The fluid level should be up to the bottom of the fill level plug.  If you only remove the pan it takes 7.4 quarts to refill the transmission up. If a new torque converter has been installed add another 2.6 quarts of oil.  If the transmission has been completely rebuild or re-manufactured it will take a total of 10.6 quarts of oil to fill to the proper level.


Fill and level check locations on the 4T45E transmission



Like every other automatic transmission, overheating is a major cause for concern.  It is recommended that an aftermarket cooler be installed in conjunction with the factory transmission cooler.

- Lack of maintenance is a potential problem that you might not be aware of when buying a used car with the 4T45E transmission.  It is recommended that the fluid be changed every 25,000 miles.  Ask for service records when buying a used car to verify that scheduled maintenance was done in accordance with the factory manual. It’s no trip to Cars Land at Disney, if you purchase a vehicle where the transmission hasn’t been maintained properly.  Steer clear of vehicles with no paperwork outlining past maintenance.

- Failure of the 2-3 shift solenoid is a common problem. The 2-3 solenoid is located inside the transmission and requires about 8 hours of labor to repair.





- Failure of the TCC PWM, which stands for Torque Converter Clutch Pulse Width Modulation solenoid.  The TCC is located inside of the valve body and is part of the internal wire harness. It is highly recommended that the internal wire harness be replaced at the same time you replace the TCC.

- Failure of the forward clutch is another common problem. The symptoms are no forward gears but the transmission still has reverse. Replacement of the forward clutch requires the removal of the transmission and complete disassemble of the transmission.

- Failure of the input sprag clutch. The symptoms are the same as the failure of the forward clutch and are no forward gears but the transmission still has reverse. Replacement of the forward clutch requires the removal of the transmission and complete disassemble of the transmission.

GM realizes that they have to up their game in the transmission department. That is why they are partnering with long time competitor Ford, to work on new transmission technology.

The 4T45E is a fairly decent transmission when not subject to too much abuse. Like any other parts on your car, the transmission has a finite life span. When the time comes to replace the transmission I highly recommend going with a re-manufactured unit. They differ from a simple rebuild in that they bring all spec up to what they were when the transmission was new. A rebuilt transmission will only have the worn items replaced.



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