5R55E with no drive/reverse

[nathansmith50]

I'm having transmission problems and I need some help.


Symptoms:

• Showing code P0755 which according to my reader is "Shift solenoid B Malfunction"
• No Drive or overdrive. Manual 1 and 2 work normally. Drive then functions for 3rd and 4th if the O/D is turned off.
• No reverse...or rather limited reverse. the truck will idle backwards but pressing the accelerator has almost no effect.
• Other codes: P1151 - Heated O2 sensor bank 2 sensor 1 indicates lean.
  P0325 Knock Sensor 1 Circuit(Bank 1)This is caused by my replacement of the engine with one that doesn't feature the knock sensor bung in the oil pan. only included because i have no idea if it's relevant.

Circumstances:

• My truck lost reverse completely not long ago so i bought a parts truck that had a transmission put into it three years ago. that transmission is now in my truck.
• It worked perfectly for about a week then lost drive for 1 day. then drive strangely came back for 2 days. then lost it again.
• When it was working i got the flashing O/D light after a little driving. this problem happened in the old transmission as well so obviously there are either multiple problems or the problem is outside of the transmission.

Attempted repairs:

• I have replaced the Valve body with an updated one. though it already had an updated one in it.
• I have removed and inspected the OD servo and all is well there. i can't seem to get the intermediate servo cover off to get that servo out.
• I have replaced the bracket that holds the selector cable because the one i had was loose.
• I have tightened the bolts on the selector under the dash which were loose and doing so did allow me to get it into first which i was previously unable to do.

Theories:

• O2 sensor problem is somehow related? this seems crazy to me but i suppose is not totally impossible.
• Engine wiring harness was damaged in the engine install. this seems most likely to me. i cut part of the transmission harness to get the old engine out since i was planning to use the new harness but the new harness had different connectors for the transmission so i had to solder the old harness back together. i know the soldering, heat shrinking, and taping work was done right though i'm beginning to doubt my wire connections as there are at least three wires in that harness that are the exact same color as others.

 

[gsbarry]

Sounds Similar to My Issue

I would double check that wiring harness for resistance across the splicing. If you look carefully there is typically a narrow secondary stripe on most wires which may tip you off if you crossed one with another - you may have to clean the wires off to see this.

I didn't have the Solenoid B code, and I suspect your other codes are unrelated, but your symptoms are similar to mine. My thread:

http://www.explorerforum.com/forums/showthread.php?t=428970

I have it mostly apart now, and the problem appears to have been a jammed input sprag - meaning removal and disassembly required. Probably not the answer you wanted to hear, but that was my unfortunate experience.

My diagnostic repair attempts (in order) were: line pressure test, update valve body w/ Ford TSB separator plate and blowoff valve, replace valve body w/ reman unit from Central VB, lastly remove trans and teardown.

I have a pdf of the ATSG manual for teardown that I can share - its pretty darn good. Just PM me.

One last thought, assuming the wires check out good, you may have had a faulty solenoid B, which was corrected by the reman VB you put in, yet that may have only been one of the problems. Perhaps you could try clearing the codes then test driving a bit, at least in 1 & 2, then see if that particular code returns. If it does not return, then you can likely eliminate the VB as a trouble spot. If it does return, I would suspect the wiring harness, given that is unlikely your reman VB has the exact same faulty solenoid from the get-go. There's a chance the code is a red herring, and your problem is internal as mine was. I had exhausted all "leave the trans in-place" remedies before I bit the bullet - as it seems you are close to doing as well.

I found that I could only remove the servos from the inside. Basically means removing the VB and using 90 degree pick (w/ the tip blunted/protected) and prying back on the servo tip. This will be tricky w/ the band apply strut in place, but possible. Obviously the snap ring needs to be out already, and get ready for an ATF shower.

 

[nathansmith50]

Well I managed to get one of the servos out...the O/D servo i was able to grab the housing with some channel locks and rotate it while pulling outward and it came right out.

the other one i can't get a grip on the cover at all.

I was thinking the sprag possibly also but it seems odd that the symptoms would disappear and then return if that were the problem.

My next step I think is the wiring.

Oh...and i did clear the codes and they came back...twice. once by leaving the battery disconnected while i was working on the valve body and the other actually clearing them with my reader.

 

[JK080]

Symptoms:

• Showing code P0755 which according to my reader is "Shift solenoid B Malfunction"
• No Drive or overdrive. Manual 1 and 2 work normally. Drive then functions for 3rd and 4th if the O/D is turned off.
• No reverse...or rather limited reverse. the truck will idle backwards but pressing the accelerator has almost no effect.
• Other codes: P1151 - Heated O2 sensor bank 2 sensor 1 indicates lean.
  P0325 Knock Sensor 1 Circuit(Bank 1)This is caused by my replacement of the engine with one that doesn't feature the knock sensor bung in the oil pan. only included because i have no idea if it's relevant.

This sounds like a broken input sprag for sure, follow gsbarry's link, he is in the middle repairing one.

 

[gsbarry]

Still Similar

My symptoms also developed over the course of a few days, it was not an instant fail and never to work again type problem. I've also found that my coast clutch was toast in addition to the OD sprag. Hard to say which component failed first and/or if one caused the other. My theory is that the coast clutch was on its way out the first time it failed, with perhaps a bit of the friction plates left. Then when the last of the friction material disappeared it became a "permanent" symptom.

The servo will have to be pryed out from the inside.

It is interesting that the Sol B code returned. I would take a second look at the wiring as well. If the the wiring checks out and the servo looks good, it's probably time to pull the trans. :roll: