Code 646 - OD Flashing

[ksknapper]

Well here is another posting for what seems like a continual problem with the A4LD tranny. Mine is a 95, 4.0 limited with about 150,000 miles. Months back I was have a bad shudder problem which turned out to be a bad front U-joint. Easy fix. But I forgot to knock on wood. In trying to nail down that trouble, I had the tranny flushed and new filter installed. No visible signs of wear in the pan. Have driven about 1000 highway miles since the fix and now the O/D light has began to flash. I immediately checked fluid level after good drive and it was well above normal on the stick (about an inch above) the appropriate level. I read the several posts about the trouble overfilling trannys causes foaming and overheating. I called the mechanic who flushed the tranny thinking he overfilled my tranny fluid and caused this issue. Long story shorter, took it to the shop and the fluid level was fine. Now feeling like a horse's petute for getting him out of bed on Sunday. I'm really questioning what wrong. There are no issues with operation. It shifts fine with no flare, with exception to when you first go from P to R there less than a second pause before pickup and then from R to 1st there is similar pause, I consider well within normal. Anyway been going through archieves and noticed other problems such as loose valve body - which seems possible with all the vibration with the bad u joint, bad selenoid, or the need of a band adjustment. Seems awefully coincidental with the tranny flush and now this.

Really wondering what caused the fluid level to rise and then return to normal. Initially thinking stuck valve. The fluid level is OK now and light remains to flash. Ran the codes and got the 646 - incorrect 2nd gear ratio. Cleared the computer and flashing remains. So there must be a problem. Haven't pulled the pan to see if there is any metal. Really seeking input as what to do first. I would possibly like to catch a break before a rebuild. I have never dealt with transmission work, but am very mechanically inclined. Thinking a valve body rebuild might be the inital way to go. Like I said I'm not a tranny mechanic but willing to learn. Figured with so much trouble and so many others having the same problem, there might be a generic approach. I will also read Glacier's valve body rebuild diary to help with the interpretation of terms.

Any help would be appreciated.

Bryan

 

[Glacier991]

Well to start, if you are a 95 you don't have the A4LD, you have a 4R44 (not sure if 95 at some point went to 4R55 or not)..

My gut sense tells me that rebuilding the valve body would be a good start. It could help, and even if you ultimately pull it and rebuild it, you will have that part done.

From a rebuilding perspective treat it as the same as the 5R55 as shown in the 5R55 valve body rebuild diary.

If you can, let me know the letters shown on the dogtag on the valve body. If it is JA, I may have something you might be interested in.

 

[ksknapper]

Thanks for the response Glacier. I'm pretty sure I've got the 4r55 as that is what it says in my manual. Maybe the Limited pkg. got a different tranny than the standard model. Personally I have no clue. In talking with several tranny shops trying to source the TC when I was trying to fix my shudder problem. All indicated I have a A4LD. Does the dogtag tell you the tranny type? Does the VB differ significantly between types? I read through your VB Diary last evening and it is pretty straight forward alot more than I would have ever imagined. Can you or others provide me with a little more info as to tackle this project as what to do first (GG). Are there certain things to look for upon dropping the pan besides shavings or parts in the pan. If I see these, I'll be certain the VB is not the sole issue and know I'll be dropping the whole tranny anyway. Another mentioned that band adjustment was the issue. How do you know if band adjustment is necessary? Slipping?? Currently I have no slipping. Also, I'm assuming I don't have to pull the tranny to get the valve body out or do I? I've read other post which suggest not to turn the VB over because of the balls. That is why I assumed you could do it without pulling the tranny. Anyway, I really learned alot reading your diary. I also noticed you mentioned the condition of the VB in the diary was exceptional. What are the signs of a bad VB? Residue? If so, how do you go about cleaning the VB? With all those intricate furrows. Some sort of chemical bath? I am amazed how the heck anyone figured out to create this engineering marval and wonder how they last as long as they do. Sorry for my lack of knowledge. If its one thing I've learned through life - is the only stupid questions are always those you never ask. I really appreciate all the input you guys have provided towards my problems.

 

[toy720]

i believe the 4r44s came behind the 3.0l motor and smaller and the 4r55e came behind the 4.0l motor.

 

[ksknapper]

I pulled the pan yesterday. There was a very minute amount of shavings in the pan. These weren't here when we did the flush a month ago. The shavings could all of fit on the tip of your little finger. Very fine. Only one piece that appeared large (the size of a sand grain) I looked for the dogtags Glacier mentioned couldn't find any numbers anywhere. I didn't pull the VB before I posted again of what are the suggestions. I'm thinking that a band adjustment may be only what is required. But I worry about the fluid levels being overfull and now normal.

New question.

I looked at my VB and it doesn't look like the A4LD in the diary but does look like the one posted in 5r55 diary. There are 4 selenoids in a row on one side and two on the other with about 6 inches between them. Is the 4r55 the same configuration as the 5r? I'm just going off the owners manual saying I have the 4r. Like I said before I don't know how to tell.

Bryan

 

[toy720]

Ok If You Want To Just Make Sure You Have The 4r55e(which You Do) Then Look At Your Door Jamb On The Saftey Standard Certification Label You Will Either Have A T In The Trans Column Which Represents(a4ld/4r44e/4r55e) Which The A4ld Was Last Put In 1994 And If You Have A 3.0 Liter You Have A 4r44e And If You Have A 4.0 Liter You Have 4r55e Now If You Have Code D You Have The 5r55e Or Code U You Would Have 4r70w. And The 4r55e Vb And 5r55e Vb Are Identical When I Rebuilt My Tranny I Had A Shop Sale Me A Used Vb And They Got It Out Of A 5r55e Soo Hopefully This Will Answer You Question On Which Type Of Tranny You Have. Also Was There Alot Of Little Metal Shavings Or Just A Bit (shavings Usually Equal Not Good).

 

[ksknapper]

Thanks Toy

I'm glad to find out the right VB. I'll have to read the 5r VB rebuild now. There was a very very small amount of shavings. All would easily fit on your smallest finger if you were to pick them up out of the pan. I would say less than 20, they look more like thin metal flakes than shavings. Someone told me as long as you have less than a spoonful you are ok. Don't know if there is any truth to that or not. I hope so, I really don't want to have to rebuild her. Would a band adjustment prove worthwhile? Like I said earlier there is no slippage in the tranny whatsoever. If it weren't for the flashing OD light I wouldn't even be discussing this. If so, where are the band adjustment nuts? Procedure in archieves?

Thanks again

Bryan

 

[Glacier991]

Band adjustment cannot hurt, and it's a no cost option.

 

[ksknapper]

Thanks Glacier


What is the procedure for the band adjustment. Is it in the archieves? I think I read somewhere about 10 ftlbs with a torque wrench. Is this the same for all bands? Are the adjustment screws on the driver side of tranny, do you do all the bands or just the one I'm getting the code for. Dang, I wish you guys lived next door .

Bryan

 

[Glacier991]

It is shown with pictures in the A4LD Rebuild Diary....spec is 2 turns from 10 ft lbs tightened, then hold the adjusting bolt and tighten the locknut. Same for both adjustable bands.

 

[toy720]

im beginning to wonder if this is a electrical issue, now the code says incorrect second gear ratio. is this saying the speed is not right when shifting to 2nd? intermediate band adjustment could clear it up but i think you would notice that you are getting really high rpms before it goes into 2nd is this the case? matbe dtr or turbine speed sensor trouble? just some thoughts. Glacier does the turbine speed sensor tell the computer what speed its turning for all gears or just od?

 

[Glacier991]

The Turbine Shaft Speed Sensor is mounted on the center support and measures the speed of the input shaft. The PCM uses the input from this sensor to determine EPC pressure and TCC control stategy. [Edit: I should add that the computer uses MULTIPLE inputs to determine these things, this is just one, but not the ONLY one!]

The input shaft is turning at all times in all gears and the TSS operates for all gears.

 

[toy720]

ahh learn something everyday. thanks

 

[jobjumper]

I have a 02' Sport that was having transmission problems, (5R55E).When I checked the fluid it was showing overfull , the O/D light would flash after I came to a rolling stop soon after resuming speed. I thought I'd try something hoping it would work, I drained one qrt. of ATF from the cooler line at the front of vehicle, then added Slick 50 ATF treatment to the tranny, the bottle didn't say anything about Mercon V compatabilty. The fluid in the tranny didn't look too bad so I didn't change it or the filter. That was done at 78,000 miles, I'm at 96,500 right now. This was done about 2,800 miles ago, I've not had any problems at all since. My situation might be different from others (fluid not blackend, O/D light flashing a few times a week, mileage) and it might go out tomorrow but, It' s working great now. If there are any problems that return ,I'll let it be known to you.

 

[ksknapper]

Thanks again everyone, I will review the A4LD diary again and do the band adjustment. I agree it can't hurt. After seeing the small amount of flake in the pan, I don't think its electrical. I really think its in the VB especially after reading the diary and seeing some of the symptoms that are also occuring in my tranny. I just hope I caught it soon enough to avoid a total rebuild. I am going to do the vB rebuild as spec in Glacier's 5r55 diary. I'm still reading through it. Is there any glaring difference between what's needed for the 5r vs the 4r. I noticed that there may be a difference between separater plates and gaskets. I just want to make sure I get the right parts initially. For Glacier or others who have experience with the kits since the diary was posted. Does anyone notice any advantages of one kit over another?

i.e. Mechanical experience, performance, easy of application, the shift kits being readily available and cost (this one really not as important to me as the others. as I figure I'm saving a bunch anyway by doing it myself). This was a great endeavor, for those who were committed to helping others. Kudos to you all. I'm sure there will be more questions later. I will do other searches in the archeives to catch those answers as they arise.

One last question, Is there a certain life one can expect out of the bands. Better said - Would the bands last indefinetly if proper care and maintenance be made or do they wear out over time no matter what?

Reason I'm asking, wondering if I just need to bite the bullet and replace the bands while I'm doing the VB.


Bryan

 

[Glacier991]

Replacing bands is a "pull the tranny and take it apart" move. If you do THAT rebuild it.

Bands last virtually forever properly taken care of. They do not "wear out" in a properly maintained and healthy tranny. Most bands in trannys I have taken apart have nearly all their material still.

 

[white95explorer]

Back track for a second. You are a getting a code saying incorrect 2nd gear ratio. This is should be telling you the actual gear ratio that is wrong. My question is, are there any drivablity issues? You said that there were not, but for you to be getting that code it seems kinda weird that there wouldnt be. You said the overdrive light was on, do you have overdrive? Also, the gear ratio's for automatic transmission depend on whether a sun gear or ring gear are being held by clutches or a band (one will be the drive gear the other is the driven) to give you that drive gear (1st, 2nd, etc). If a band were loose then it wouldn't be holding the ring gear so, would that be throwing your code? The speed sensor in your transmission should detect the correct speed for each gear. If the speed were incorrect, i.e. say 2nd is supposed to shift at 20mph and is shifting at 15mph etc, then could that be throwing the code to your computer? I guess I just dont see how rebuilding the valve body is going to fix the code. Yeah, its responsible for shifting gears and what not, but I dont see how it would be at fault for the code you are getting.

Chris

 

[ksknapper]

Great points Chris, to reiterate - I'm not noticing any difference in the shifting. It shifts through all the gears properly. Properly does not mean that the shifting may not be at the proper time or setting as should be. I.e. Whether it supposed to shift at 15 and now 20 or vice versa causing the code. This could very well be the case. I just note that it goes through the gears with no long delay between gears - no flare or hanging and also no slipping. That is why I think the band may be loose but not loose enough to create slippage but enough to throw the code. As Glacier mentioned, it is a no cost fix to adjust it to the proper setting. As for the VB rebuild, I already have the pan off - which I did to see if there was noticable material in the pan. Now that it is off and the VB is right there. I am going with Glacier's recommendation that I might as well rebuild the VB while I'm at this point. A low cost additional solution to what might be causing this problem or lead to other problems down the road. And if other problem happen later the VB will be done. Based upon reading others posts, I may have been dodging bullets for a while. Seems others are doing tranny maintenance at 85 to 125 thousand miles. I'm sitting at 155,000. I will take a picture of the small amount of shavings I got from the pan and post those for input. Again I hope I caught it very early and life might be left in the bands not to warrent a full rebuild. There is some flare from park to Reverse and from Reverse to 1st that I've noticed which was largely taken care of when the VB was rebuilt for others. Also pondering what caused the overfill condition when checking the fluid after the light began flashing that is now back to normal. Thinking a sticking valve in the VB may have caused this. The overdrive does work.

I'm glad you all are sticking with me in this thread.

Bryan

 

[BrooklynBay]

Here is another thread with similar information: http://www.explorerforum.com/forums/showthread.php?t=152989

 

[ksknapper]

Well thought I would let you know the final posting for this thread. I went to adjust my bands. I had success in adjusting the front band. Fortunately it was the first one I did. I started tightening the second band, got to about 7 lbs and heard a snap. Then I thought $(#^(. I then pulled the valve body and got a magnet and retrieved the hook portion of the band. The part the adjuster fits into. It snapped right where it connects to the band. Must have had a stress crack in it. Initially thinking that this crack may have lead to the band becoming looser than the computer wanted thus threw the code. I am grateful that it broke while I was adjusting it and not 70 mph. That was a huge piece of metal. No telling what it would have done at highway speed. Didn't know if they were prone to breaking there or not. I was inspecting it and noticed that one side had been wearing into another part. Thinking this is where the small shavings in the pan came from. I not to worried about it, cause its lasted this long.

I now have to pull the tranny and do the rebuild option. I wanted to thank all those who provided input I just hope I'm qualified to perform the band replacements.

Bryan