Trans problem

[greenExploder94]

I have a 94 explorer but do not know which trans I have. I was driving down the road the other day when the truck died I put it in neutral and started the truck up but when dropping it into drive or any of the drive gears she just dies without any sounds. I have been told by 3 different people that it is the torque convertor but my uncle said it is the front pump. If anybody has had this problem can u please tell me which one it is Is it the Torque convertor or is it the front pump I already spent the $175 for the torque convertor from Autozone and want to make sure that I got the right part for the truck.

 

[FR-425]

Stuck torque converter clutch

Sounds like TTC is stuck, as well as the governor. When the engine stalled it failed to downshift and left the TCC locked. Oh your trans is the a4ld. Only auto trans used in these.

Note: You may be able to recover from this without disassembling anything:

1. Disconnect battery

2. Disconnect transmission harness.... here:

3. Reconnect battery.

4. Start engine in park (DO NOT SHIFT YET)and let warm up for 20 minutes, we need to get the trans warmed up to.

5. Strike the out-put housing with a rubber mallet (this is where the governor is) couple of good angry bangs to knock the gov. loose.

6. Shut down the engine and reconnect the trans wires.

7. Important : start engine in park. Let it warm up again. Then quickly shift all the way to 1st.

If it doesn't stall you have successfully unlocked the TCC.

Good news here is that this is really not a component failure but a rarely encountered set of circumstances i.e. engine stall while rolling.. the exact timing of you putting it in neutral, trans was still cold, etc. yata yata.

So if you can get it unstuck this will likely never happen to you again.

It is definitely time to "SeaFoam" and change the fluid and filter.

Get the "media" type filter not the wire screen one, and be sure it has the long pickup tube for 4x4 application.


Some more info:

Something to consider before you swap the torque converter. If the TCC issue is not resolved you will have the same problem.

Quoted from trans Guru's:

To help trouble shoot "Lock up" problems on the A4LD. We offer this explanation of the control system used. Basically it utilizes both governor pressure and a signal from the ECM to control "Lock up" The converter shift valve when in the downshifted position allows line pressure to oppose the TCC shuttle valve and prevent it from upshifting even when the solenoid is activated. The converter shift valve is upshifted by governor pressure and the converter shuttle valve is controlled by the solenoid. Both must normally be in the "Lock" (upshifted) position to obtain "Lock up". The TCC shuttle valve is the actual control for "Lock up" so if it is stuck in the upshifted position the converter will Lock even though the converter shift valve is in the downshifted position.

 

[JK080]

I have a 94 explorer but do not know which trans I have. I was driving down the road the other day when the truck died I put it in neutral and started the truck up but when dropping it into drive or any of the drive gears she just dies without any sounds. I have been told by 3 different people that it is the torque convertor but my uncle said it is the front pump. If anybody has had this problem can u please tell me which one it is Is it the Torque convertor or is it the front pump I already spent the $175 for the torque convertor from Autozone and want to make sure that I got the right part for the truck.

There is a valve in the valve body called the converter clutch shuttle valve that has a spring, the spring can break or get weak, when this happens it will kill the engine in gear or the valve itself is stuck.

This transmissions (A4LD) pump is not known for causing this problem.

 

[FR-425]

I have to disagree JK..

The Shuttle valve is held open by hydraulic pressure against the springs pressure to prevent up-shift (TCC lock). It will then not up-shift until governor pressure is released.

This way it is dependent on the vacuum modulator and not just TPS for TCC lock up. So at full throttle TCC is delayed until vacuum returns. Otherwise it would lock at 45mph no matter the throttle position.

So a broken spring will cause the shuttle to remain in the "prevent up-shift" position.

You then have a transmission that never reaches TCC lock, and therefore cannot get stuck in the lock position.

Correct me if I'm wrong, I suppose I may have it backward here.

But Let's not confuse the original question ask by Green Exlpoder.

Even if the spring is broken he can recover it by doing as I suggested.

I was just trying to give him a direct and simple approach to help confirm the malfunctions origin and a "possible" solution, Not open another lengthy debate over the inner details of the a4ld.

My last post is not intended to be the fix-all answer to a stuck TCC,

After all the torque converter may just be smashed.....

The valve body could be cracked...

And whole host of nasty things...

I was hoping he would give it a try and come back with more info or just a "can't believe that worked"

As moderator you should know that direct contradiction is never helpful.

I've given him an alternative to help with trouble shooting without pulling the trans to get more info on what's really going on inside.

 

[JK080]

FR-425

First off thank you for your post, forums like this are very helpful for people who are seeking answers to their problems. What makes them so usefully is the different suggestions from people who may be in the know.

I at no time intended to contradict you and your information, and the valve may not be his problem anyways, however not share that info won't do the original poster, you, or anyone else any favors, I guess I could have keep that little secret to myself but then what's the point of a forum like this?

I have seen the birth and the death of the A4LD and have dealt with its MANY problems over the years. I have seen at least a dozen times the converter clutch shuttle valve spring break and sometimes jamb the valve, when this happens the converter won't release and it will kill the engine in gear. I even have the OE part number for the spring E5TZ-7L490-A, it might not be available today but it was 10 years ago.

Here is the way the system works and how the valve redirects the fluid to apply the converter.

The spring and line pressure keeps the valve in the unlocked position, line pressure works with the spring not against it. What I have seen is pieces of the broken spring jamb the valve and prevent it from moving back.

Just like the last sentence you quoted from some "Transmission Guru's"


Sorry its a little small

 

[FR-425]

Read it again JK, your wrong.

hydrolic pressure "opposes" the spring.

If hydrolic switching alone was used here there would be no need for a spring.

Thank you for the diagram which also confirms this.

This isn't to say that a broken spring can't cause permanent lock.

I guess I should have just responded with "rebuild the trans" and cut my losses.

I WILL REFRAIN FROM ANY FURTHER ATTEMPTS TO HELP PEOPLE TROUBLE SHOOT THEIR TRANSMISSION WOES AND JUST LEAVE IT TO YOU.

 

[FR-425]

Keep in mind I have already performed this TCC unsticking on my own transmission and am still driving around 40,000 miles later. TCC functioning normal.