How Can I Tell What's Wrong with my Transmission? (Ford 4.6L, 5.4L)

How Can I Tell What's Wrong with my Transmission?

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.

Two of the Most Common 4R70W Transmission Failures

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:

  1. Transmission is ‘slipping’.
    1. Internal mechanical failure is the root cause of transmission ‘slippage’.
    2. A low level of transmission fluid (usually due to a transmission fluid leak) can also cause the transmission to slip.
    3. 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.
  2. Transmission does not shift out of gear.
    1. This generally happens when the PCM senses an electrical problem and commands the transmission to stay in what is known as ‘Limp In Mode’.
    2. In ‘Limp In Mode’, the automatic transmission will not downshift or upshift at all.
    3. 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 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:

  1. 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:
    1. P0700: Transmission Control System Malfunction
    2. P0750: Shift Solenoid A Malfunction
    3. P0751: Shift Solenoid A Performance or Stuck Off
    4. P0753: Shift Solenoid A Electrical
    5. P0755: Shift Solenoid B Malfunction
    6. P0756: Shift Solenoid B Performance
    7. P0758: Shift Solenoid B Electrical
    The above list is by no means a complete list... but it'll give you an idea of what to expect when retrieving transmission diagnostic trouble codes.
  2. The speedometer does not work and you might have one of the following trouble codes:
    1. P0500: Vehicle Speed Sensor Malfunction
    2. P0501: Vehicle Speed Sensor Range/Performance
    3. P0502: Vehicle Speed Sensor Low Input
    4. P0503: Vehicle Speed Sensor Intermittent/Erratic/High
  3. Your vehicle's automatic transmission will stay in only one gear no matter what the vehicle speed.
  4. As you accelerate your vehicle, it feels very underpowered. This is due to the fact that the transmission is starting out in 2nd gear.
  5. 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 most important things that will tell you that you have a solenoid or internal transmission sensor problem is:

  1. You'll have a specific transmission diagnostic trouble code.
  2. The automatic transmission does not ‘slip’, no matter how many times you road test your vehicle.
  3. The automatic transmission stays in ‘Limp In Mode’.

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)...

“The secret to success is to go from mistake to mistake without losing your enthusiasm.”