Gen 1 Autoshift. Won’t hold gear

[billr]

Yes!! What a story Jim! Head you stuck yo it your patience is huge! 
 

I resemble that part Milk crate test drive.  Lol mine was a Camp chair! 
 

 

[HERO Maker]

Congratulations Jim!  Sounds like a huge job to tackle and you done did good!

Way to go. 

Are you by the dam (just below it) or up at lake level somewhere?

[Jim Hicks]

I NEED YOUR HELP AGAIN GENTS.  This problem is still there.  I got so frustrated, I parked it in the barn and moved to other projects.  I need to get this resolved.  Let me give you the update. I replaced the Power Interface Module (PIM) and triple checked all of the connections and crimps.  I replaced the XY shifter with a genuine Eaton Remanufactured XY shifter, and replaced all sensors with genuine Eaton sensors. Replaced the wiring harness with an Eaton wiring harness.  (Everything is new except items inside the shift tower, the shift tower harness, and the Transmission ECM.). Batteries are around 14V while running and north of 13V when idle.  All wiring connections are clean.

Last summer we made the run from Houston to San Antonio (3 hours) and back over a week end after replacing most of these components and had no issues.  That is when I last updated.  Shortly after that we loaded up the Harley and left for South Dakota.  I made it 15 miles from the house when the first problem appeared.  (Same symptom as before). Running at highway speed under no real load to speak of it stumbled and downshifted to 9th.  I pulled over, reset the truck by cycling it off then on and proceeded on our trip.  Before long it happens again.  Over the course of the next 40 miles it got progressively worse.  Eventually I turned around and headed home.  We made it part way home before I ultimately had to get it towed.

The symptoms were all the same as explained before.  It would not stay in gear.  Initially near the top, but ultimately even in lower gears.  I checked for active codes, and it had none.  Once I got it home I pulled the floor pan and double checked everything.  This is the point where I replaced the sensors.  Until this point they had not been replaced.

(By the way I did the Troubleshooting on the existing speed sensor, and it passed.  I replaced it anyway.  I the connected the trailer, and took it for a test drive on some farm to market roads around here.  I tried to stay close to the house, but let it stretch its legs.  Around 45 minutes into the test drive, problem comes back.  Same symptoms. I limped home.

Another symptom that it has exhibited, and I have not explained before is tied to fuel delivery.  It’s kind of hard to explain but here goes.  If I am running in 10th gear and it stumbles and downshifts, I essentially have two options.  Pull over immediately, reset the ECM and take off again. Or I can try to hold speed in ninth.  If I try to hold speed it will slowly reduce in RPM over a period of minutes, sometimes seconds.  Essentially it is not responsive to the throttle.  You have to hold the throttle to the floor and simply watch it decelerated.  If you try this for a few miles, it behaves almost as if the fuel pump is not providing enough fuel.  Ultimately it behaves as if it is starving for fuel.  The only way to recover is to pull over and reset.  Except resetting is no longer enough, the fuel rack needs to be reprinted as well.  It essentially pulls all of the fuel from the fuel rack.  This typically involves siphoning fuel from the tanks, repriming the DAVCO, venting the fuel rack, rolling the engine over and manually keeping the DAVCO topped off to provide prime.   While doing this i do not recommend having the wife hold  tools while getting Diesel fuel on the wife’s clothing.  The last part ultimately leads to a disgruntled wife.  (At least both times we attempted this it did.)

If i look through all of the old “Inactive codes” I do have one code that can lead ultimately lead to a bad ECM.  I cant remember it specifically, and I would need to go back to my notes.  I think it might have been either “35” or “67”. In either case, it stated “Do not replace ECM unless the code is active.  As I stated I have not had any active codes all year.  I am using all of the inactive codes I wrote down over a year ago when this all started. There are no active codes today.

Ultimately I decided I would do one of two things.  1). Take it to “Chalks Trucks / Transmmissions” here in Houston and tell him to fix it, or find someone to help me figure out how to make it a manual.

Keep in mind that “Chalks”. Is an Eaton authorized transmission shop, and is one of the few Eaton Authorized Remanufacturing centers in the US, according to what I understand.  I called Chalks and ask if  I pull the existing ECM, can they bench test it for me.  They say no, that they  “Just replace parts”. Naturally that doesn’t set well, so I am hesitating to pay a wrecker to tow it to them to “Replace parts”

I started looking into what it takes to convert to a manual, and learn that process is fraught with pitfalls.

If a $1500 ECM fixes the problem, I am not opposed to just replacing it and getting my rig back.  The issue is that the troubleshooting guide is not pointing me that direction, and I don’t want to “Easter Egg” this by throwing more parts at it only to find I misdiagnosed the issue.

For those of you who have some opinions on this I would love to discuss with you on the phone.  If you know any experts on the Gen 1 Autoshift, I would love to talk with them on the phone.  Thanks for listening, I look forward to your feedback.

Please feel free  to text me at 713-899-3346, I would love to dialog with you on what I should do next.

[Darryl&Rita]

What engine? I've not seen it mentioned.

[Jim Hicks]

Good Question Darryl,

It has Volvos VED12 in it.  That is where i understand the complexities come in if converting to a manual.  Evidently converting the Cummins to a manual, has more predictable outcomes in resolving ECM communication settings.  Doing it with a VED12 appears to generate communications issues that can be difficult to overcome.

[TreyandSusan]

Hey Jim,

These guys are not close by (TX) but they might provide some insight. They appear to understand the Autoshift. http://www.caclutchandgear.com/auto-shift-transmission-common-problems/

[Jim Hicks]

Thank you Trey!

[Darryl&Rita]

Not too fluent on the VED12, but try Dave at Midwest ECM. Midwest. He's a straight shooter.

[Darryl&Rita]

Due to keyboard diagnostics, I'm trying real hard to not tie your original issues back to a fueling issue, but this new info is pointing me in that direction. The computer monitors throttle position, engine load, and other parameters to determine the correct transmission gear. If fuel is restricted, the engine load is perceived as high, prompting a downshift. Talk to Dave, he should be able to help.

[TreyandSusan]

Non-mobile website link for Midwest ECM - http://midwestecmrepair.com

Thanks for the resource Darryl

[Wrknrvr]

   Years ago I had a fuel issue on our 2000 Volvo that was intermittent. I would find the fuel filter low on fuel. Now this is on a N14 so the motors are different. But what turned out to be was the fuel line going to the motor compartment, had a loose connection where it picked up fuel from both tanks. There is a part there that collects fuel from both tanks equally. The fitting our our truck had a 90 degree fitting on it. At first I just tightened it as we’ve were going over Maria’s pass near Glacier N P. After tightening it if run dood for for the end of the trip. I finally took it apart and cleaned the threads and reinserted the fitting. It worked for the summer and made just north of Las Vegas in the fall. Tightened the fitting again and made it to or winter spot. With the 90 degree fitting I could not rotate the fitting as it wanted to twist the fuel line.

  I finally took the front piece of the fitting off to fix the threads. But the threads had worn such that when I tried to tighten them the threads would not tighten. Ordered new valve assembly and installed it.I chased the treads on the fuel line to clean them up. The fuel line 90 degree turn caused a problem to tighten that fitting. Now it has been a few years so that fix could be a little fussy in my brain.

  Also I looked at a 2003 truck and they had a straight line with a fitting that would not cause that problem 

  Now should be 6 ground studs on the motor side of the firewall on your truck. 3 on each side.   They are probably 10 mm nuts on them.  Many moons ago I had a odd miss. No codes , no nothing pointing anything in particular.

 

  I called friend in Montana and he said to clean all grounds.    Aaallll of them. Never had that miss since. 

 

 Maybe even put a throttle position sensor on it also.

  Stay safe,   Vern

Edited January 31, 2021 by Wrknrvr

[Jim Hicks]

Thanks all.  Daryl, I will give him a call and walk him through my scenario.  Verny I appreciate your advice as well.  Regarding the fuel line, I am aware of the fittings you mention.  I have done work there before.  I will take a look at the configuration.

 

I like your suggestion on the grounds as well.  I will visit all six of those grounds. 

[steiny93]

Not an expert on the VED12, I stayed in cummins land... 

but, If the downshifts only occur after the engine 'stumbles' and after the downshift you have loss of power it seems like the issue could be less trans and more engine.  From the sounds of it you can only regain full power after a 'refill' of the high pressure fuel system (this part looks like it could be the root of the issue).

I'm assuming you've swapped fuel filters and checked the lines for any damages, failures?  Does the truck loose prime sitting?  Or is this only at operation issue? 

Sounds like during operation either the truck isn't able to provide enough fuel to the high pressure system or its being errantly told to not deliver the fuel (I'm not sure how the volvo's control that system).  Guessing the typical diagnosis would be to put a gauge on the fuel system and see what pressures are being maintained; or perhaps you can pull that real-time.

Good luck, and keep the updates rolling, it's nice to see how these adventures end.