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I have seen a plethra of E4OD problem threads popping up lately. I hope that this thread will help guide those with issues through the diagnostic and maybe even the repair process. Hopefully this can save some of you some time, money, and frustration.

The E4OD serves it's purpose but it's purpose is not high mileage use in a Bronco nor offroad use. The E4OD is an electronically controlled transmission, that like many A/T's, does NOT like heat. Read on and find your specific issue.

I encourage those familiar with the E4OD to help me by providing your information, experiences, and providing and correcting information in this thread.

This is in no way the end-all be all of transmission diagnosis. This is only a means of helping you to diagnose your own transmission. If you feel that something has lead you to a dead end, post. This is in no way a replacement for a QUALITY transmission shop (read: NOT AAMCO!). I am not a mechanic nor am I a transmission specialist. I am merely someone who has dealt with my own E4OD problems and am trying to apply that in order to help others. Read on at your own risk

Step 1:

So you've encountered a problem. Let's start by using the KISS method. Check your transmission fluid. To do this ensure that the truck is in park, running, and on level ground. If the fluid is low, top is off. DO NOT OVERFILL YOUR TRANSMISSION. This will cause the fluid to froth and will be as bad as not having enough fluid.

You want to also make sure that the fluid is a nice bright red and does not have a burnt odor. If it is dark or has a strong burnt order, change your fluid, filter, and pan gasket.

Doing this is very simple. Drain the pan, drop the pan, pull old filter out, install new filter, reinstall filter, gasket, and pan. Refill with fluid. Remember, your transmission is running between 150 and 200*F. The fluid is sitting in a pan and does not quickly dissapate heat. Let your transmission cool before working on it.

"My transmission doesn't have a drain plug". You have only one option this time. Crack the pan and drain it. Ford offers a pan with a drain plug and you can search for writeups on drain plug installation.

Here is the P/N for the Ford pan w/ the drain plug F81Z 7A194 BA

Step 2:

Pull codes! Here is a writeup on how to pull codes:

Here are what the codes mean

From here you can pretty much diagnose any issue that you can imagine. The EEC-IV is good at helping us determine what is acting up in our vehicles. Most times it will come down to a bad sensor, solenoid pack, etc. We'll get back to these later.

I got one of the following codes. What do I do?

121, 122, 123, 167

You have a problem with your TPS. At this point you can either further diagnose that issue or replace the TPS.

566, 617, 618, 619, 621, 622, 626, 627, 629, 641

Your solenoid pack is affected. You either have a bad solenoid pack or a problem in the harness or connectors. A new solenoid pack can be purchased from Ford. Here is a thread with some good solenoid pack info

634, 654, 667, 668, 675,

636, 637, 638, 657

This was caused by either a faulty TOT (Transmission Over Temperature) sensor, a bad connector or harness, or the transmission was overheated.

Step 3:

The newest Bronco is, at this point, 12 years old. Connectors get dirty, the break, and wires get brittle. You may find that you are having a transmission problem and that it is just a dirty connection. So what connectors are there on the E4OD and what do they do?

The connector on the driver's side of the transmission is for the MLPS (Manual Lever Position Sensor). This tells the transmission what gear you have selected so that it may act accordingly. The connector on the passenger's side of the transmission is the shift solenoid connector.

Pull these connectors and inspect them and the wiring very thoroughly. Get some electric contact cleaner and spray down the connectors on the harness and the transmission thoroughly. After you have done this, be sure to let them dry. Reconnect them and see if your condition approves. Pull codes again and see what you are left with.

Step 4:

VSS and TPS cleaning and adjusting

The VSS (Vehicle Speed Sensor).

These work by reading the speed of the tone ring as the teeth pass by the sensor. Your sensor is located on top of the rear differential. It is held on by a bolt. Remove the bolt and pull the sensor. You likely will find that it is covered in metal shavings. Don't panic, this is normal. Wipe the VSS clean and reinstall. The same goes here, inspect the connector and wiring and clean. Pull codes again.

VSS Testing

Another sensor that likes to play tricks on the E4OD is the TPS (Throttle Position Sensor)

So now you've done all your tests and your transmission is still having issues. I will break down some of the more common issues not including internal hardware failure.

Common Transmission Issues

I'm getting a hard shift from 1st to 2nd

This is called "safe mode" also referred to as limp mode. The transmission is essentially protecting itself from any further damage you may cause. The transmission is forcing itself to shift using pressure rather than the shift solenoids. Be aware that this is normal when there is a problem and you should continue with your diagnosis.

More info on limp mode

I have a hard/delayed shift into reverse

This is an extremely common problem with the E4OD. The transmission requires a lot of fluid to engage reverse. This takes time and often leads to a very firm shift. Don't worry, you arn't the only one. Do a search and you will find lots of threads regarding the issue.

Here is an article on how to fix it. Be warned, it will require internal modification.

I don't have Reverse!

Repeat all the above. Hopefully it is an MLPS but could be an internal problem.

My transmission will not shift into 3rd or 4th but I am not getting any codes

This is a tricky one. It could be many things but if you have been offroading, mudding, or driving through deep water, I recommend you replace your alternator and see if this happens. It is possible that the rectifier circuit went and the alternator is sending a mixed AC/DC signal to the PCM confusing it.

My truck wants to stall when put in reverse

This may or may not be accompanied by irraddic idle and/or codes. If no codes are found pull the IAC (Idle Air Control) sensor and clean/replace as needed.

Here is an IAC cleaning writeup

Another potential problem is that the transmission filter may have dropped into the pan. This is easy enough to fix. Remove pan, reinstall filter, fill with fluid.

There is a clip made that will help hold the filter in place since from the factory the filter is only held in by the o-ring. Look 3/4 of the way down this page.

It looks like this:

There is also a magnet from Ford that works as a filter retainer. p/n F3RZ-7E290-AC

My truck starts off in 4th gear

This can be accompanied by a draining dead battery and a self diagnosis not initiating. This can be caused by the EEC relay.

More info here:

When I come to a stop my transmission feels like it goes into Neutral

This is likely an issue with your MLPS.

My trucks slips into neutral and then slams into gear whenever it wants


My Speedo needle is bouncing

Either an issue with the VSS or the tone ring located in the rear diff. Inspect and replace as necessary.


After 94 the MLPS was redisigned with a different connector to keep out water. I recommend buying a new MLPS from Ford. It will require you to repin the harness connector.

MLPS Testing Pointers/index.html

MLPS Sensor Values

The Ultimate TPS Thread

When I come to a stop my truck lurches. Stalls at lights

Could be an issue with the TCC. Check the and clean the wiring on the solenoid pack connector. Test the MLPS.

Shift Solenoid Testing

My transmission is leaking fluid out the front

One of three conditions has likely happened.

1. The transmission too much fluid and was venting through the front pump

2. The transmission overheated and was venting fluid through the front pump

3. The front pump seal is bad.

Replacing the front pump seal is not involved once the transmission is out. Simply remove the old seal and install the new one. Purchase the seal from Ford. A transmission removal and install thread will be posted further down.

External trans filter, cooler, and thermostat install

E4OD Removal and Installation

Other Usefull Links

Random transmission parts


Hard to find transmission parts

This thread will be updated regularly as I progress and people help build the content. I will also re-arrange it for easy of reading. For now, please enjoy and add your input.
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