The 4L60E transmission is the direct descendent of the 700R4, and as such already had over a decade of refinement put into it before it ever even made it into production. This means that even the early ones were pretty good from day one of their production life. While there have been many case changes and internal changes throughout the years. Ok, time to stop rambling. Lets get into 4L60E problems and how to troubleshoot them.
It is important to understand a few things about how an automatic transmission works. There is fluid that goes through the 4L60E that has three jobs:
- Energy movement
That’s a lot for one fluid to handle. Motor oil is only responsible for lubrication and cooling and is changed way more than transmission fluid. Tranny fluid is one of the most neglected items of vehicle maintenance. So before you go crazy thinking about what part may be giving you a difficult time, try making sure that the fluid isn’t the culprit. This is especially true if you’ve recently towed something or been racing. So if your 4L60E is acting funny after you’ve done one of these things, why don’t you just go ahead and change the fluid just to be safe.
Here is a good write up on low transmission fluid signs.
This is a good writeup on taking care of a tow vehicle
If the 4L60E is not shifting through the gears like it should be and the service engine soon light comes on than you’ve probably entered limp mode, limp mode is gear 2, 3, and reverse. It will have no overdrive and no first. The first thing that I would check is whether or not is is getting power from the ECM, and whether it is sending a signal back to it. It’s way more likely that this has happened than you have a major issue.
If it isn’t an electronic issue causing limp mode, it’ll be a mechanical one.
If you find that your vehicle is vibrating at highway speed, this is often caused by a loose torque converter. You’ll probably find that you’ll get this feeling at particular rpm ranges. For instance, maybe you’ll feel a shutter from 1800-2000 rpm, but the engine will be fine above or below this range. That is either the torque converter or harmonic balancer. Make sure you aren’t confusing the shutter of a poor running engine with the vibration of a transmission with a loose converter.
Common 4L60E Problems
4L60E goes into neutral when shifting into third gear
This is one of the most common problems with the 4L60E. It is pretty easy to diagnose. The vehicle will shift from 1’st gear to second gear with absolutely no issue whatsoever, but than it acts like it has shifted to neutral. The engine is usually under a pretty heavy load at the time, so it’ll tend to redline before you realize what happened. Good thing these engines have rev limiters! It can be a pretty scary feeling.
This is caused by a burned out 3-4 clutch pack. And, the 3-4 clutch pack is done in by the 3-4 piston. There is a giant rubber O-ring around the piston that will shrink due to heat and age. Nearly everyone is going to have to take it on in for a rebuild. Replacing the clutches in an automatic transmission is not a job that is easily done whatsoever. There is a lot that can get messed up in the 4L60E
4L60E has forward gears, but no reverse
This is also a pretty common issue with the 4L60E. More than likely the reverse input snap ring has sheared or snapped off. It can also be caused by the sun shell breaking. The most common problem is probably going to be the low reverse clutch pack. The booster valve could also be an issue.
Below is a pretty good video on common causes of 4L60E reverse going out.
Many people will bring their vehicle in and complain that the transmission is shifting really hard between first and second gear. This is another really common problem with the 4L60E. It would probably be a good idea to check the throttle position sensor and see if it is within it’s normal operating parameters.
Here is a good article on TPS issues.
Below is a good video on TPS diagnosis.
If you’ve had problems with the 4L60E after a rebuild, check this article from LS1tech.com.
Whatever is going on with your transmission, I hope that you are successful in fixing it, and you don’t end up losing an arm and a leg on repairing your 4L60E. Good Luck!