How can I tell if my automatic transmission is bad? How can I tell if it's just a shift solenoid that's bad? How can I tell if my automatic transmission needs an overhaul? These are some of the most frequently asked questions I get and if you're having an automatic transmission issue with your GM rear wheel drive vehicle... this article might have some of the answers you're looking for.
Now, although in this article I won't be showing you how to tear down your transmission, it will help you to find out if your electronically controlled 4L60-E transmission issue is due to a malfunctioning shift solenoid/sensor or internal damage.
You can find this tutorial in Spanish here: Cómo Diagnosticar la Falla de la Transmisión Automática 4L60-E (at: autotecnico-online.com).
The most important thing to know, when trying to troubleshoot a transmission problem, is that the automatic transmission (4L60-E) in your rear wheel drive GM vehicle usually fails in one of two ways:
Each one of the above conditions has a specific cause and in the next sections, we'll explore this a bit more in-depth.
The electronically controlled 4L60-E has several solenoids and sensors that the PCM needs to control the upshifts and downshifts. If any one of these sensors/solenoids fail or the fuse(s) that supplies the solenoids gets blown... the transmission will go into ‘Limp In Mode’.
What makes it pretty easy to tell if the automatic transmission failure is just a solenoid related issue... due to the fact that the transmission doesn't ‘slip’.
Here are some very specific symptoms you'll see when a transmission solenoid goes bad:
In conclusion, I want to emphasize that the most important things that will tell you that you have a solenoid or internal transmission sensor problem is: One, you'll have a specific transmission diagnostic trouble code. Two, the automatic transmission does not ‘slip’, no matter how many times you road test your vehicle. Three The 4L60-E stays in ‘Limp In Mode’ (note: see Transmission with Both Solenoid Failure and Internal Damage).
I've written a tutorial on how to test the A and B shift solenoids (also known as the 1-2 or 2-3 shift solenoids) that may be of help and you can find it here:
Let's turn the page and find out more about the specific symptoms a 4L60-E with internal damage...
“For instance, on the planet Earth, man had always assumed that he was more
intelligent than dolphins because he had achieved so much —the wheel,
New York, wars and so on —whilst all the dolphins had ever done was
muck about in the water having a good time. But conversely,
the dolphins had always believed that they were far more
intelligent than man —for precisely the same reasons!”
The Hitchhiker's Guide to the Galaxy