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Other causes of T/C lock unlock


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Driving home tonight then same old demon came back again. At 50-60 mph t/c started locking and unlocking. This thing is giving me a run for my money. My alternator is within spec, all grounds have been checked, cleaned, and had dielectric grease applied. Just to waste time and money I relocated the alternator ground cable away from the alternator across the radiator. Also I blew the 25.00 on the BD Apps noise isolator. I don't know what else to do now. Is there anything else that can cause this problem?, Anything!

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I really can't help much, I did test drive a truck  that did what you are saying and it was obvious because the wife asked what was going on. The truck I did purchase some 5 years ago has the DTT transmission and it has a DTT Noise Filter just a thought. Not sure if it is any better then what you have.  We put a lock up switch on my boys truck and when his had some slipping issues we locked up the TC and realized that his problem was the torque converter going bad since locking it up did not solve the issue had the TC changed out and valve body installed and some minor upgrades done inside the trans and worked fine.  Hopefully it is not a bad torque converter.  BUT this is symptomatic of the noise from the alternator and or bad grounds.

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I really can't help much, I did test drive a truck that did what you are saying and it was obvious because the wife asked what was going on. The truck I did purchase some 5 years ago has the DTT transmission and it has a DTT Noise Filter just a thought. Not sure if it is any better then what you have. We put a lock up switch on my boys truck and when his had some slipping issues we locked up the TC and realized that his problem was the torque converter going bad since locking it up did not solve the issue had the TC changed out and valve body installed and some minor upgrades done inside the trans and worked fine. Hopefully it is not a bad torque converter. BUT this is symptomatic of the noise from the alternator and or bad grounds.

I have the transgo shift kit and blocked the passage for the lockup but have not yet installed the lockup switch. Maybe that's an option.

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hmmm,   last time  I  helped my neighbor out  with this   exact same   problem,    ended up being his  apps  sensor.     I see you  already did the  noise cancellation part,   I wonder  If the  'spike'  is  overwhelming  the  filter you put on?  It doesn't take much to   fool the  pcm... and   unlocks  the  TCC  right away.

 

Then when you are running  faster,  the  apps  in a  different- less worn spot  and the noise  is  much lower.

Seeing you  are only having this problem at a certain speed,     This is  all I can come up with!

 

edit:  you posted  just as  I  submitted this...   you said it  DONT  mess up with a trailer.   you are  pushing the  accelerator  down more with a load,  and it's  not in the  'problem area' of the apps..  :shrug: 

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hmmm, last time I helped my neighbor out with this exact same problem, ended up being his apps sensor. I see you already did the noise cancellation part, I wonder If the 'spike' is overwhelming the filter you put on? It doesn't take much to fool the pcm... and unlocks the TCC right away.

Then when you are running faster, the apps in a different- less worn spot and the noise is much lower.

Seeing you are only having this problem at a certain speed, This is all I can come up with!

I had an Apps code not long ago. When I checked the sensor the bolts weren't tightened all the way so I tightened them, did the Apps reset and it ran fine for a while. Could the Apps sensor cause this problem. Seems like everything I've read say that when people have this problem the first thing they do is change the apps but it doesn't fix it. Do you think the apps may actually be my problem in this case?

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Driving home tonight then same old demon came back again. At 50-60 mph t/c started locking and unlocking. This thing is giving me a run for my money. My alternator is within spec, all grounds have been checked, cleaned, and had dielectric grease applied. Just to waste time and money I relocated the alternator ground cable away from the alternator across the radiator. Also I blew the 25.00 on the BD Apps noise isolator. I don't know what else to do now. Is there anything else that can cause this problem?, Anything!

The factory alternator grounds thru the mounting bracket to the engine block. Are you saying you ran another ground wire in the past?

 

I heard the main charge cable from the alternator is the one you separate from the other wires to help stop this problem.

 

I used an Ohm meter and found resistance in the grounding thru the mounting bracket. There are some articles about running a separate ground wire from the Alternator.

 

My hunting stopped when I lifted wires off and away from the alternator.

 

If you need a new APPS get the Timbo APPS. It cost far less and is much better quality.

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I had an Apps code not long ago. When I checked the sensor the bolts weren't tightened all the way so I tightened them, did the Apps reset and it ran fine for a while. Could the Apps sensor cause this problem. Seems like everything I've read say that when people have this problem the first thing they do is change the apps but it doesn't fix it. Do you think the apps may actually be my problem in this case?

This is  where my 'expertise'  runs  out!

I was lucky  2 years ago  when I helped my neighbor out,  and  the first thing we tried (replaced)  actually worked!     So, to answer your question,  yes.  It may very well be the  root problem..

But   I'd  sure like to hear someone elses   thoughts  on how to test  before shelling out more bucks!

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http://www.dodgecumminsapps.com/page04.html

 

here is  a checklist of  things to try BEFORE ordering a new  timbo apps  (165 bucks) 

 

I tried to  copy the  list,  but  it  didn't  want to  work  in here.

 

4 out of the 5 things  they  recommend you've tried..  but  check out the   speed sensor in the tailshaft 

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The factory alternator grounds thru the mounting bracket to the engine block. Are you saying you ran another ground wire in the past?

 

I heard the main charge cable from the alternator is the one you separate from the other wires to help stop this problem.

 

I used an Ohm meter and found resistance in the grounding thru the mounting bracket. There are some articles about running a separate ground wire from the Alternator.

 

My hunting stopped when I lifted wires off and away from the alternator.

 

If you need a new APPS get the Timbo APPS. It cost far less and is much better quality.

Yeah, I ran a new ground wire that was a little heavier outside of the mounting bracket.  Thanks for the tip on the Timbo APPS.

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http://www.dodgecumminsapps.com/page04.html

 

here is  a checklist of  things to try BEFORE ordering a new  timbo apps  (165 bucks) 

 

I tried to  copy the  list,  but  it  didn't  want to  work  in here.

 

4 out of the 5 things  they  recommend you've tried..  but  check out the   speed sensor in the tailshaft 

Good tip.  I removed the wiring harness, cleaned connections and applied dielectric grease but I did not remove the sensor itself. I will be doing that tomorrow. Thanks.

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When you say that the alternator is within specs, do you mean the AC noise is very low? Should be less than 0.1 volts ac noise otherwise it makes transmission do the dance.

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Where do you get those speed sensors? Want to put one in the tool box. Thanks

Doorman p/n 917602. Any of the parts stores can get it. At Napa they crossed the number to their brand and had it in stock. You can also get it from RockAuto. Cost is about 20.00 everywhere.

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Reinstalled alternator fuse and test drove. I guess it didn't really make it worse because it's doing the exact same thing. Guess I can rule out Alternator again. Can also rule out speed sensor and wiring because I replaced the sensor and inspected the wiring, all good. Can rule out grounds and other connections because all check out good. Both batteries are in good condition and charged correctly. Been through all of the Timbo sites checklist and everything checks out. Looks like I'll be buying an APPS sensor.  Presently have the negative cables unhooked and going to do APPS reset and test drive again.  Seems like every time I do the reset it runs good for a while so maybe that's the key.  If you guys have any other suggestions please let me know.

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