Newbie here, and this I my first post.  I am a 61 year old farmer in South Carolina and my truck is a 2006 Dodge 3500 with a 5.9 Cummins.  I'm about to hit 150,000 miles on the odometer and consider this truck just barely broken in.  The transmission is a Garmon Stage 2, built 2 years ago, and I run an EFI Live tow tune.  Of all the trucks I've owned since 1978, this one is by far my favorite. At least till now, Lol.  About a year ago it started cycling the torque converter in and out between  45 and 50 mph.  This problem occurred before I put the EFI Live tune on it.   I have taken it back to Garmon twice and to my local transmission shop many times with no improvement.  I have read through the "Torque Converter Lock/Unlock Issue" thread for the 2nd Generation Trucks on this site twice and tried several fixes suggested there with no improvement.  In fact, researching this issue is what brought me to this site. With a scanner on the truck, the torque converter is doing exactly what the ECU is commanding, and so the consensus is there is nothing wrong internally with the transmission.  If I set the cruise at say 35 mph and then accelerate up to 45-50 mph, it will not cycle the torque converter.  In tow haul at 45-50 mph it jumps between 3rd locked and 4th locked with or without the cruise on.  So far I have replaced the Output Speed Sensor, Throttle Position Sensor, Alternator, Fan Clutch (not for this reason).  I've checked AC voltage on both alternators and get an approx. reading of .01.  I had ordered a new alternator before finding this site and finding out how to check for AC voltage. I've also run the truck with the fan clutch disconnected and with the alternator disconnected with no improvement.  I couldn't find the alternator fuse, so I completely disconnected the alternator for the test.  I've cleaned every ground I can find on the truck, and the battery connections appear to be good.  Both batteries are new and fully charged.  The local transmission shop put some filters on it, but I had him remove them because I didn't want a band aid fix, and because the side effects were unbearable.  I am really at a loss as to what to do next, and started a new thread because most of the information on the 2nd Generation thread is dealing with earlier model trucks, and locations of wires, electronics, etc. have been changed over the years.  I apologize for the length of this post, but there's probably some things I've missed.

so when the TC is locking and unlocking is the ecm commanding it to do that?  

 

 

 

Yes

 

Interesting.  I have not seen a 3rd gen with this problem!  

 

Mine is cranky like this on occasion.  This helped my 2nd Gen. http://www.dodgecumminsapps.com/page04.html

 

1 Clean battery terminals and body grounds

2 Clean ground strap at PCM located at passengers side firewall.

3 Remove and inspect the middle plug on PCM, this is the plug that contains transmission control wires.Clean with contact cleaner.

4 Remove, inspect and clean 8 wire plug located on drivers side of transmission

5 Remove, inspect and clean speed sensor plug located at tail housing of transmission, replace sensor if needed. It is an inexpensive sensor.

 

I've seen a lot of info on here dealing with the 2nd Generation trucks, but it's hard to find anything on the 3rd.  I can't be the only one with this problem though. 

If the pcm i sasking for lockup then I don't think it is a typical issue we see with our 2nd gens

8 hours ago, CSM said:

2 Clean ground strap at PCM located at passengers side firewall.

 

That is not a ground strap for electrical ground just provides shielding for the PCM case that's all. The actual PCM ground is the passenger side ground cable. Should pay more attention to the main negative cable on the passenger side being that provides the ground for the PCM, ECM and the VP44. That little ground strap again is only to ensure the PCM case is part of the ground plane. Like my truck the PCM is mounted to plastic screw nuts on the steel plate. So this would produce a floating ground plane for the PCM case and possible allow EMF noise to pass through the case. 

Ok, so I should concentrate on the ground leads from the passenger side battery as well as the ground from the PCM case?

Hi all, 2003 3500 SRW 48re Quad cab Laramie 4x4, Same thing, 3 - 4 back and forth.  I don't think mine will lock up.

 

I have changed tcc/lockup solenoids with harness, gov solenoid and transducer, 3-4 accumulator spring, speed sensor.  After talking to the owner of DNJ Components, and doing 4th gear line pressure test, its not a transmission problem.  Also I have drove with the scanner hooked up, Like Team Tailandscale said, the computer is commanding 4th and sometimes it will hold for a minute in 4th and lockup, them instantly both solenoids are shut off.  

 

After reading the threads on here I started messing with alternator,  I unhooked both wire from the back and the truck drove better, still not right.  Next step for me is taking alternator in and testing the diodes.  I want to also rebuild battery cables and grounds around truck.   

 

Just wanted to chime in, a 3rd gen doing this.  It is driving me crazy, Along with guys wanting 25k for these trucks with 200k miles on them.  I have a 12valve with a 6speed and i love the cummins, but guys need to be realistic, they aren't made from unobtainium or anything. 

Most guys that test the alternator don't test for AC noise. They will often test okay, even on a brand new one but are still throwing too much AC noise.

You need a good volt meter to test for it. Like a Fluke or other good VM.

 

hopefully Michael Nelson will chime in too for a bit more information as I cannot remember how low the AC test is supposed to be.

sub .05 ac is ok

At .05 AC volts may or may not create random issues. Kind of breaking point depending on the vehicle. Beyond 0.05 it tend to get more absolute and more of a problem.

After 13 months and  many new parts, PROBLEM SOLVED!!!  The spiral wire from the output speed sensor was bad.  Thank you to everybody for chiming in.

I've heard of a few reports of output speed sensors causing lockup issues. Glad to hear you found the issue and got it fixed.

Took my alternator to parts store and the ripple test showed .8 AC volts, which the machine passed.  Asked them to test the on an their shelf and it tested 1.1 on the ripple test.

 

What should I do, order one from dodge or replace the diodes?  Asking for advice cause this is driving me crazy at 45 mph lol.  

 

I'm going to check the wires on oss after Team Tailandscales good fortune.

Remember the store tester is running at full load when test diodes. The home test we do is at idle loads. So the numbers are different but the results should be the same. I would put the alternator back on the truck and just leave the field lead disconnected and take it for a ride. If the problem is gone then the alternator is creating excessive AC noise. 

I Did that before, it seemed like it was less severe, but it was still doing it.  Going to start going through ground wires, battery cables, ect. tomorrow.

There is only 1 ground wire to worry about. It on the passenger side battery. All other grounds are for secondary stuff like light and horn.