The 4R70W automatic transmission in the Ford 4.6L or 5.4L usually fails in one of two ways: It'll either start slipping (when in Drive) or will go into ‘Limp In Mode’...
...And so, you may be asking yourself: How can I tell if my automatic transmission needs an overhaul? How can I tell if it's just a shift solenoid that's bad? 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 automatic transmission issue is due to a malfunctioning shift solenoid/sensor or internal damage.
By the way... the info in this article can also be applied to older AOD-E equipped Ford vehicles with OHV V8 engines.
4R70W automatic transmission problems boil down to two basic types of failure. One, the most common, is caused by some sort of electrical failure and which causes the vehicle's computer to command the automatic transmission to stay in 2nd gear no matter what the vehicle's speed. The second type is when the transmission suffers some sort of internal damage and the transmission starts to ‘slip’ when in Drive.
Here are some more specifics:
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 4R70W automatic transmission in your Ford car, pick-up or SUV is electronically controlled via several solenoids and sensors, all of which live inside the transmission (well, all except the vehicle speed sensor). If any one of these sensors/solenoids fail or the fuse(s) that supplies the solenoids gets blown... the automatic transmission will go into ‘Limp In Mode’.
What makes it pretty easy to tell if the automatic transmission failure is just a solenoid/electrical related issue... is 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:
Let's turn the page and find out more about the specific symptoms an automatic transmission with internal damage (and that will require an overhaul)...
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Charles M. Schulz