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).
Two Of The Most Common Transmission Failures
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:
- Transmission is ‘slipping’.
- Internal mechanical failure is the root cause of transmission ‘slippage’.
- A low level of transmission fluid (usually due to a transmission fluid leak) can also cause the transmission to slip.
- In layman's terms, ‘slipping‘ can be best described as having the transmission go into neutral, although it's in drive, and not move the vehicle no matter how much you step on the accelerator.
- Transmission does not shift out of gear.
- This generally happens when the PCM senses an electrical problem and commands the transmission to stay in what is known as ‘Limp In Mode’.
- In ‘Limp In Mode’, the automatic transmission will not downshift or upshift at all.
- The usual cause of this condition is a bad shift solenoid, although some internal mechanical problem/damage can also cause this.
Each one of the above conditions has a specific cause and in the next sections, we'll explore this a bit more in-depth.
How Can I Tell If It's Just A Solenoid Failure?
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 is that the transmission doesn't ‘slip’.
Here are some very specific symptoms you'll see when a transmission solenoid goes bad:
- The PCM is also gonna' light up the check engine light (CEL) and store a specific shift solenoid diagnostic trouble code. You'll see one or several of the following transmission diagnostic trouble codes:
- P0700: Transmission Control System Malfunction
- P0751: 1-2 Shift Solenoid Valve Performance
- P0753: 1-2 Shift Solenoid Valve Electrical
- P0756: 2-3 Shift Solenoid Valve Performance
- P0758: 2-3 Shift Solenoid Valve Electrical
- The speedometer does not work and you might have one of the following trouble codes:
- P0500: Vehicle Speed Sensor Malfunction
- P0501: Vehicle Speed Sensor Range/Performance
- P0502: Vehicle Speed Sensor Low Input
- P0503: Vehicle Speed Sensor Intermittent/Erratic/High
- Your 4L60-E automatic transmission will stay in only one gear no matter what the vehicle speed.
- As you accelerate your vehicle, it feels very underpowered. This is due to the fact that the transmission is starting out in 2nd gear.
- At speeds over 35 MPH, the engine feels like it's over-revving. This is also due to the fact that the transmission is staying in 2nd gear and the gear ratio provided by 2nd gear is gonna' keep the engine working pretty hard at any speed above 35 MPH.
In conclusion, I want to emphasize that the three most important things that will tell you that you have a solenoid or internal transmission sensor problem are:
- You'll have a specific transmission diagnostic trouble code.
- The automatic transmission does not ‘slip’, no matter how many times you road test your vehicle.
- 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.