Guys, I have a 06 Hurricane motorhome that starts out ok in 1st gear, shifts to 2nd gear and then at 25 mph slams into 5th gear and the tow/haul light starts flashing. The odometer on the dash also goes to dashes.

It's throwing a code of P0722. I checked wiring to the speed sensor from the pcm and it is good. I replaced the speed sensor on the transmission and still the same issue. I do not see any problems with the pins in the plug.

This is consistant. If I shut the engine off and restart the engine it will start in low again and make the shift to second and then at 25mph slam into 5th and throw the same code again.

The engine is a 6.8 with a 5R110W transmission. It acts like the pcm cannot keep up with the pulses coming from the output speed sensor.

I am at a loss. The problem is repeatable. It is consistant. I am not one to believe that a loose wire or bad connection would result in the same symptoms at the same speed and then reset when the engine is shut off and restarted.

Any help appreciated.

 

Post this on the 99-16 forum, because you have a 4R100. Another place to post is the 6.0L forum, even though you have a 6.8L, where your PCM has an adaptive learning strategy that is cumulative (as long as the PCM remains powered) and different than the 6.0L. But you want to get the attention of Mark Kovalsky... a former Ford transmission engineer who actually worked on calibration and cooling of the 5R110W. He is more likely to see your post on one of those other two forums than here.

Don't rule out a blown diode or two in your alternator. When an alternator blows a diode, the diode more often than not breaks down gradually, which means that the alternator can still function, although not optimally. The fact that the alternator is still functioning usually means a long period of time where no indication is given to the driver that a problem is brewing. If the battery light doesn't illuminate and stay lit, and the truck still starts and functions, how would a driver know?

An increase in electro magnetic interference (EMI) is one of the side effects that can occur when one or more diodes degrade inside the alternators. This EMI can distort the readings of magnetic Hall Effect sensors... of which the Output Speed Shaft sensor is one. When the OSS signal is skewed by EMI, then you're right, the PCM gets bad data from the OSS, and that can very much effect how the transmission behaves... badly in my experience.

This may or may not be the root cause of the issues you are experiencing, but it is a likely suspect, cloaked in an unlikely component. Who'd have thought faulty transmission function could have anything to do with an alternator? Well, I can report that there can be a linked cause and effect between the two, so don't rule a weak or faulty alternator out as you move toward resolution by pursuing the diagnostics routine for P7022, reaching out to Mark K on a forum he frequents, and checking all of the ground connections throughout the vehicle (not just a tug test, but a complete unbolt, clean, and reattach procedure that consumes time and yet sometimes solves problems).

 

Thanks for the information. I went back over all wiring again and checked the replaced the sensor again. The problem stayed until this afternoon when it magically disappeared. This scares me. This means it could rare its ugly head again and most likely at the most inopportune time. I unplugged the sensor, unplugged the ecm, and giggled the wiring to cause it again and it's gone. I'm not happy because I didn't find a reason and make a repair. I guess I'll have to wait until next time and try again. Mark my word, it will return.

 

How did you check it? Did you check for continuity, short to ground, and short to power?

There are three speed sensors in the transmission. Which one did you change?

No, he does not. This is a 2006, the last year for the 4R100 was 2004. This is a 5R110W transmission.

 

Yes, this is a 5R110W. There are two speed sensors on the transmission. There is a third on the rear differential.

I replaced the output shaft speed sensor. That's what the codes said were a problem. Using a Snap on Verus Pro we monitored the signal when driving and it would disappear around 25 mph.

I checked the wiring at the plug at sensor for voltage and had 10 volts. I checked the 10v source to the ground wire in the plug and had continuity and 10 volts. Running a wire to the plug in the pcm I checked continuity of the signal wire from end to end and it was good. There are no connectors between the sensor and the pcm. It appears to be one solid harness.

The problem disappeared on its own right now and I'm afraid it will come back. I will have to deal with it then. I just hope it's not on the road somewhere desolate or in heave traffic and not being able to move safely.

Again, thanks for the replies. Any advice is appreciated. I was hoping someone was going to say something like "Yea, I had that problem and this is what I did to fix it" Maybe this was a anomaly.

 

No.

On the transmission, from front to rear, is the turbine speed sensor, the intermediate shaft speed sensor, then the output speed sensor. There is also a speed sensor on the differential.

 

The turbine speed sensor must be internal as there are only two sensors on the outside of the transmission. I believe the forward external sensor is the intermediate shaft sensor as I have researched it. I'm certainly learning more about a 5R110W then I planned on but it's nice to know how it operates.

 

I did know that, which is precisely why I specifically recommended the OP seek you out. I simply made a mistake in my post. I was thinking 5R110W the hole time. See... I just made another mistake! But it's the thought that counts, right?

 

I did not realize that the turbine and intermediate speed sensor is one unit.

 

OK, I got a hard set this time. It would not take off in 1st gear, in fact I think it only had 5th and no reverse.

I decided to drop the pan and take a look at solenoids. There was no noticeable debris in the bottom of the pan to indicate any clutch or bearing damage. Something I did notice was the reverse clutches and steels in the back of the transmission were excessively loose. There was a gap of about 1/3 inch. I knew that couldn't be right and downloaded a ATSG manual for specifications.

I pulled the transmission and tore it apart. Every clutch pack, bushings, and hard parts looked great until I got to the rear clutches. There is a snap ring in the case that should hold those clutches in place. It was just laying in there. I reached in and removed it without having to pry it out from the case.

The snap ring was wavy and I thought it was damaged as this is the first time I've seen one like this but after further research it appears to be wavy on purpose. What I found is diesel transmissions get a flat washer and gas engines get a wavy washer.

I plan to replace all clutches and steels since I have it apart but I am concerned about the snap ring coming loose again.

Does anyone know why that would have happened? Again, this is a motorhome with 29k miles on it. I did not buy it new so I do not know if it had any previous issues. I don't want it to happen again.

Edit to add: It appears the snap ring I have in the transmission is a upgraded part. The ends of the ring curve outward to catch a boss on the case to keep it from walking during operation. Thats the research I have been able to come up with so far.

 

One type of upgraded snap ring in a 4R100 has to have a groove in the case itself machined to except the upgraded snap ring. I have no idea if this is snap ring you are working with, but the point here is just to bring up the reminder that sometimes upgraded snap rings have to have other case or companion modifications to accommodate the heftier size of the new style ring to keep it in place.