'91 A4LD No Overdrive..

Hi guys & gals. I've had this problem for about 3 months now..
http://www.explorerforum.com/forums/showthread.php?s=&threadid=84534
and starting to feel the pressure of getting this fixed once and for all. If you read through the thread, you'll see that my tranny had gone out and once I changed the fluid/filter I got my tranny back EXCEPT for overdrive. Since we've only been driving it in town, no OD has not been a problem till now. My commuter truck is having small problems and might have to use the XLT as a commuter starting next week, so I need OD. Please help, by pointing me in the right directions. After doing a search, I've come across of things to check/replace (money depending of course). Please add/subtract to list to help me get this figured out. What should be checked first, etc..

1. TC lockup selenoid
2. Mass airflow sensor
3. Speed sensor
4. ????

BTW, all other gears work fine. Here are the gears I feel it go through 1-2 (shifts around 20 mph) 2-3 (shifts around 30 mph) 3-4 (shift around 45 mph) then that's it. It does about 2500 rpms at 65 mph. Also it will hunt for gears when moderate pressure is put on the gas at this speed. Thanks guys/gals.

1st question I have for you. Which isn't working OD (3-4 shift you said you can feel the 3-4 shift) or the torque converter lockup (TCC can engage in either 3rd or 4th and can feel like a shift)?
Diagnosis for both circuits is essentially the same, since they are nearly mirror images of each other. The only difference is in the PCM's control.

1st question: I've already asked, which circuit is failing? How many shifts do you feel with the selector in D instead of OD? The usual test to TCC lockup is: while cruising at 50 mph, press brake pedal with left foot. Does engine speed increase (indicating TCC unlocking)?

2nd question: Is failure to actuate circuit electrical or internal to transmission? Check for any obvious breaks in wiring (get wiring diagram. www.autozone.com has adequate wiring diagrams for this). Check for 12V at red wire in transmission connector. Enter EEC-IV output state test and, while monitoring voltage drop across solenoid, verify that PCM can switch the solenoid. Test drive vehicle while monitoring voltage drop and see if PCM tells the solenoid to switch. Use good circuit for reference if test seems inconclusive.

One note, since I think you are referring to TC lockup. My '92 A4LD suffers from a condition that I think is called "soft" lockup. The PCM tells the torque converter clutch to lockup, and sometimes I can even see a small change in engine RPM. But the lockup isn't as "solid" as it should be. I have been wanting to drop the valve body and clean it out real good to make sure there isn't crud clogging the solenoid or the valves preventing the clutch from locking up as it should (If anyone is familiar with correcting a "soft" lockup, I would appreciate any feedback. Send me a PM).

Sorry to be so long winded. Cover those bases and see where that gets you.

Thanks for responding..

1. The last shift I feel is very subtle but does not feel as if the TC is locked up. In last gear if I give it a little gas the rpms jump up accordingly. Not like in OD when it's solidly locked up. If it's supposed to lock up solid in 3rd, then it's no doing that. I'll do that 50 mph test as I understand what your asking.

2. In D, I only feel 1-2 then 2-3 thats it. No more changes in gear. If I slip it into OD, then I feel one more subtle gear change (drops from about 3k to 2500)

I can check for voltage while standing still, but I'm unfamiliar with the "EEC-IV output state test". How can I tell that the PCM is telling the selenoid to engage? Does the voltage drop? If so, how low?

Thanks again for you help.

What you are describing sounds like the OD (3-4 shift) is functioning, but the torque converter lockup isn't there or is "soft", like mine.
EEC-IV output state test is entered after the continuous codes have been output as part of the KOEO test (see www.dalidesign.com/hbook/eectest.html or a good manual for instructions on running all tests). You measure voltage drop across a component by putting your voltmeter leads on both sides of the component. Since the solenoid is the only load in the circuit, the voltage drop across the solenoid should switch from ~0 V to ~12 V.

I think I gotcha..

Guess I have some testing to do. What are the possible outcomes of this test?? If voltage tests OK, does that mean that the selenoid is not responding to the voltage change? If the voltage is not changing when it should, what would be the possible culprits behind this? I'll do those tests tonight and get back here tomorrow with results.

MrShorty, I appreciate your help.

Sorry I've taken so long to respond; I hope it hasn't delayed you running the tests. Let me try to explain the underlying logic.

The purpose of the output state test is to answer the question, "Can the PCM tell the TCC to lockup?" You're just watching the voltage to see if you can see the PCM switch the solenoid on and off. If not, then the problem lies somewhere in that electrical circuit. If you don't have a wiring diagram yet, it will help understand how the circuit is set up.

I'm in deep now!!

MrShorty, no probelm, I just appreciate you taking the time to help me out. Tell you what, if you're ever in Cali and want a free fishing trip, let me know webmaster@anglernet.net .

Anyhow, I did the 55 mph test. While cruising in 4th gear, I apply the brakes and the rpms remain the same. They don't budge. I guess that means the TCC sel. is not locking up.

Thanks for the links. I have the haynes manual and I printed out the shematics from autozone. I also printed this (www.dalidesign.com/hbook/eectest.html ) out but need to read it 2-3 more times before I figure it out. I've done testing on my OBDII mazda, but didn't find the socket on the ford. I know it doesn't use the same type of procedure. Ok, but let me get down to what I need right now.

I've dropped the pan to change the oil and give a looksy. The oil was still clean and read. The local dealer had the tcc selenoid and I figured I'd buy it and try replacing it.
Well, I'm stuck. Theres one bolt that holds the selenoid, but there's a cam that's holding it in place. I can't pull it out because of this cam. I tried turning the seleniod, but was not able to move it.

Anyone know how to remove/replace this selenoid? Thanks..

My question, how is this an emergency? This is what this forum is for. This belongs in general explorations, questions for the stock Explorer.

Originally posted by Mbrooks420
My question, how is this an emergency? This is what this forum is for. This belongs in general explorations, questions for the stock Explorer.

Click to expand...

Well, if you go back to the top and read the WHOLE thread you'll see that I need to get overdrive up and going by TOMORROW. I'll be putting 150 miles a day on the Exp. until I get a new commuter vehicle. With no OD my mileage is going to be a little on the low side. I'm sorry YOU don't feel this is an emergency. It's all a matter of perpective I guess. If the moderators feel this is not an emergency, they can move it. No biggie.

If you feel you need to talk about this further, just pm me or e-mail me

Hi guys & gals. I've had this problem for about 3 months now.

Click to expand...

Usually the best time to fix something is before the last minute. Procrastination can be expensive.

Back to my questionn....

Anyone know how to remove/replace this selenoid?

It is locked in place with a flat pin and I can't move it. Looks like I need to spin the solenoid, but can't figure out how to do that. (No room)

I think you need to remove the valve body to get the solenoid out. I would suggest, before attempting to drop the valve body, 1) that you get a good transmission manual (ATSG manual available from places like www.bulkpart.com or equivalent, maybe available at library) so you know how to get it apart and how to get it back together.
My second recommendation would be to finish the diagnosis. Since you're in a hurry (if you haven't already abandoned the project for later) it seems like a waste of time dropping the valve body to replace the TCC solenoid when the real problem could have been fixed with a little solder and electrical tape.

Thanks again

I worked on it that morning and almost pulled the valve body before realizing I might be making a big mistake. I had unbolted most of and back the bolts went.

I am printing this thread out and hopefully I can fix in the near future.

The mods can move this thread as it is no longer an emergency since I lost my job as of today Layoffs suck.

I have all the same problem with my 91. Here is what I've do so far: http://www.explorerforum.com/forums/showthread.php?t=295068 But mine is not locking in 4th OD. Yes it is locking the TCC. Can tap the brake to see the rpms increase.