One of the most common problems with the 4L60E is that the reverse gear will go out. Having no reverse can be a tricky issue, especially if you happened to park against a wall. Below we will cover the most common problems that cause reverse to fail.
4L60E No Reverse Causes
Low Reverse Clutch Pack- The most likely part of the 4L60E to have failed in reverse is the low reverse clutch pack. Typically, when any of the clutch packs wear out, they begin to drop debris in the transmission pan. If the pan looks good, and the fluid looks clean, than it’s likely not going to be the low reverse clutch causing the problem.
Valve Body Issues- A bad valve body can make the reverse gear not work in the 4L60E. If the valve body ends up warped, or if the gasket fails, it’s entirely possible that the gear won’t engage.
Booster Valve- A bad booster valve can leave you without reverse in a hurry.
Sun Shell- A broken sun shell will cause the 4L60E to lose reverse. It is known to snap where the splines meet the shell itself.
Here’s a short but sweet YouTube video that covers some of the most common issues that cause the 4L60E to lose reverse. In this example it’s the sun shell that has caused the issue.
Diagnosing No Reverse
If you are an observant person you might be able to help yourself identify which problem caused the 4L60E to lose reverse.
If there was an egg smell for a while when engaging reverse, it’s more than likely going to be the friction bands/low reverse clutch pack. The clutches in an automatic transmission wear just like the simple clutch of a manual transmission. When they go out it often leaves a putrid smell. It should also have started to feel a little weird for a bit before it failed. Almost like it wasn’t quite biting al the way.
If reverse suddenly fails with no warning, it’s very likely to be the sun shell. Is it possible that the engine was revving fast when reverse was engaged? Alternatively, was the vehicle moving forward? If so this can cause the sun shell to fail.
Those are the primary reasons that the 4L60E fails in reverse. It could be something else, but not nearly as likely as one of the reasons listed above. Good luck fixing your transmission.