Ok Gang...I've got a for sure way to diagnose torque converter lock up issues where it lock and unlocks at about 45-50 MPH. I had a gent call me yesterday with this problem and he's replace both batteries, alternator and the APPS sensor. Attempted all the different wiring issues (adding ground, tinfoil etc.) nothing worked. Like I told him the truck ran 11 years without all this stuff and doesn't require any wiring change to make it work. What it needs is the damaged part to be replaced. So he's returned the wiring back to stock setup.Now I told him to unhook the alternator fuse and take it for a ride... Guess what... No problems! Even though he replaced the alternator it has a damaged diode in it and it bleeding AC noise into the electrical system.So before doing any wiring mods, tinfoil, adding grounds, adding filter... PLEASE! Bench test your alternator! This is the second time I've suggested this and both time resolved the torque converter lock up issue.

You have to remember, AC sine waves are what radio broadcasts are. If you leave the +BAT terminal connected on the back of the alternator, you can use that legnth of wire as a transmitter antenna.

Disconnect the entire alternator to remove it as an issue.

 

Ed

Update: truck ran perfect for several days, and then the dreaded TC cycling was back :-(

Rechecked alternator - still good, so decided to do another APPS reset. Runs perfect again! Since I don't have a lot of history on this site, the only things I have done out of the host of fixes floating around for the TCC issue are the BD noise filter several years ago, and most recently, re-routing the large ground wire away from the alternator. All my battery cables and terminals are brand new and the truck overall is still like new with less than 32k on it.

Question for MoparMan or anyone: is it possible the APPS itself is going bad? Is it possible the alternator could still be going bad even though the voltage checks are perfect? I have no other issues with the truck other than the TC cycling - no MIL codes, no dead pedal, no limp mode, no nothing. Any other ideas? I really hate shot-gunning potential "fixes" and trying the other ideas like re-routing more grounds, wrapping wires, etc. without understanding root cause, but I am perplexed at finding the root cause.

My alternator was charging fine, until I had a shop that cold test it for diodes specific and failed on that test, also when you check ac volts on back stud of alternator make sure you rev truck up slowly and use a good meter and not a $5 one. Cheap one will not work. From what I understand normal is .02-.05 ac/v and .1 ac/v max. My alternator was at .6 when revved up to 2500 rpm and .02 at idle, it make since why my problem was noticeable at hwy speeds and up hills. I hope my surge is gone for good and wish you luck with yours, I know how frustrating it is. And yes apps do go bad but I ended up changing mine thinking it was the problem and it didn't help. Rule out alternator for sure before you change somthing else, parts stores will not help you with their testers, find a place that does it for a living or get a meter like Fluke.

Edited December 25, 201410 yr by Dieselfuture

JUst wanted to give an update, as of yet the transmission has been flawless!!! I took it to the shop today and had the tranny flushed, new filter and new and gasket installed. The guy at the shop said that everyting looked perfect inside.  Not bad for never having anyting done from new to 131,000 miles.  I told him about the Diode circuits as discussed here and he said he had heard of that as a fix as well.  Thanks again for the help on here guys, I will be donating soon...as soon as I get my motorcycle out of the shop. I dropped it off today thiinking that I was only going to have rear tire replaced and ended up needing both done and the fork seals need replaced as well, so my bill went from $300-$800!!!  Oh well you play you pay am i right?  SLAP IT HIGH!!!

I am having this same issue and have replaced the TPS and took the alternator fuse out and neither one has worked, what I've read this has worked for everyone else but I am still experiencing the issue. The problem only occurs part of the time, sometimes it shifts and locks normally and others the issue occurs. Do you have any other recommendations or ideas that i could attempt to solve the problem?

You still have to unplug the field lead from the alternator as well. Retest and report again.

I'll update my torque converter locking/unlocking status.  Whenever mine was acting up, I would tighten the battery cables, and it would go away.  I was using some marine batteries with 3/8 studs, and the usual stack of cables.  I noticed that every time I checked, (basically whenever the lock/unlock thing flared up), I could tighten the nuts a little bit.  The problem got some better when I added lockwashers, so maybe they were backing off, or maybe the springiness of the washer helped make the connection better.  I also noticed that I was overtightening the nuts and very gradually pulling the studs up through the lead terminal.

 

Anyway, this winter my 3-year-old, $60 Walmart marine department closeout batteries finally began to stagger, so I put in two new, appropriately-sized Interstate batteries with normal posts.  My normal-battery-post tactic is to use the solid brass clamps with studs, and convert all the wires and cable to ring terminals (already done on the previous battery setup). 

 

So I realized today that I've gone several months now with no lock/unlock problems. 

 

I guess one other factor is moisture--there seemed to be some correlation between moisture and the problem (for me).  Apparently, moisture is a thing of the past here in NW Oklahoma, so it's no longer a factor.  But maybe it will rain next year, and I will have one more data point.

Still working perfectly!!!

hello gents.  new to the site.  i didnt realize mike had his own site...duh...

ive seen his posts elsewhere, but didnt think to check...

so.  i am having the tc issue.  cant say its related to wet or dry, tho im in southern cali and its been super dry here.  ive noticed the issue really stood out after a starter change, disconnected batteries for change out.  today, i did the voltage test.....and say 14v dc....and for ac....it started high....and progressed to zero in under 5 sec.  what am i doing wrong??

i really like the truck....but this is just one of the issues im having....i believe ive got trans issues as it shifts funny and doesnt like to shift into OD unless i back off throttle or drive faster than 60mph.

ill search other threads for input on trans issues.

thanks for the time.  looking forward to the knowledge.

Disconnect the alternator fuse and go for a drive. If the problem is gone the alternator is shot.

ill give it a shot. 

if problem persists...what else could cause it?  low fluid? speed sensor sending funky signals to apps??

also, does the alt. fuse provide power to the whole box....and if so, my truck wont run that way.  i pulled the battery fuse... 50amp....truck starts...but dies a second later, i cant drive it.

The alternator fuse just takes the alternator out of the system. You still have battery power just no charging and the truck should run until the batteries die.

thanks man....

 

ill be giving this a shot soon

ill give it a shot.

if problem persists...what else could cause it? low fluid? speed sensor sending funky signals to apps??

If the truck dies when you pull the alternator fuse it probably means your batteries are toast. It should run for quite a while with out an alt. Did you reset the apps after you had the batteries disconnected? If not this can cause some drive ability issues.

Only new issue I have is the tc hunt. All else...existed before disconnecting batteries.

Update to the update, its back!!!  I barely have 2000 miles on the truck since "the fix" and it started hunting, unlocking and bouncing back and forth.  Now what?

Pull the alternator fuse and the field wire and go for a test drive if it goes away the alternator failed. (Warranty time...)

Update to the update, its back!!! I barely have 2000 miles on the truck since "the fix" and it started hunting, unlocking and bouncing back and forth. Now what?

Ok guys just a quick tidbit of information. Has anyone here corrected the grounding issue on the trucks prone to this issue?

If the diodes are constantly taking a dump it would seem to me that only 2 reasons for this to occur are happening. A: poor construction and B: ground based issue. I myself have alot of altered and added ground wires on the truck. Especially from the PCM to the body ground and the alternator to ground. I will be going through my grounds in the winter months to clean them also and add some sealer to them to prevent further and future corrosion.

Mike has been nailing this problem on the alternator diode trio failure for some time but I have taken additional precautions to help with future issues.

Edited October 3, 20159 yr by Vais01

Can't remember if I posted in this thread .... but Mike on a 24v TPS ppump .... same issues .... different cause.

There was a dead spot in the TPS itself ... so basically as you moved the throttle the voltage went up .... but right near lockup there was a dead spot and voltage goes to 0. Lockup in and out.

New TPS .... a good.

Ok guys just a quick tidbit of information. Has anyone here corrected the grounding issue on the trucks prone to this issue?

If the diodes are constantly taking a dump it would seem to me that only 2 reasons for this to occur are happening. A: poor construction and B: ground based issue. I myself have alot of altered and added ground wires on the truck. Especially from the PCM to the body ground and the alternator to ground. I will be going through my grounds in the winter months to clean them also and add some sealer to them to prevent further and future corrosion.

Mike has been nailing this problem on the alternator diode trio failure for some time but I have taken additional precautions to help with future issues.

 

PCM, ECM and VP44 grounds are all on the passenger side battery cable. Take a peek you'll see on cable running toward the PCM and cowling. There is no body ground on these units. The only reason for the cheap strap to the PCM is because it mounted into plastic clips the most likely reduce the shielding effect of the case.

 

 

Can't remember if I posted in this thread .... but Mike on a 24v TPS ppump .... same issues .... different cause.

There was a dead spot in the TPS itself ... so basically as you moved the throttle the voltage went up .... but right near lockup there was a dead spot and voltage goes to 0. Lockup in and out.

New TPS .... a good.

 

Typically if the APPS sensor drop out of range for anytime it "should" throw a P0122 code for low volts because it did drop too low. In your case with the p-pump set up I'm not certain what the other system errors will do to impact the reporting.

 

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes-cummins/151-p0122-apps-sensor-signal-voltage-too-low

 

Monitor & Set Conditions

Accelerator Pedal Position Sensor (APPS) voltage is monitored when engine is running. DTC may be stored if low voltage is detected on APPS signal circuit or low voltage is detected between Engine Control Module (ECM) and Powertrain Control Module (PCM).

Possible Causes

• 5-volt Supply At APPS Shorted To ECM Sensor Ground
• APPS Signal Circuit Shorted To ECM Sensor Ground
• 5-volt Supply To Ground
• APPS Signal Circuit Shorted To Ground
• APPS Signal Circuit Open To ECM
• PCM (APPS) Short To ECM Sensor Ground
• ECM (APPS) To PCM (APPS) Circuit Shorted
• ECM (APPS) To PCM (APPS) Circuit Open
• Short To ECM Sensor Ground
• Accelerator Pedal Position Sensor (APPS)
• Engine Control Module
• Powertrain Control Module