TC Cycling
09-04-2009, 10:37 AM
#1
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TC Cycling
Hey guys. My TC is cycling (from locked to unlocked and back to locked for just a split second), when the engine RPMs are about 1200-1400 with light load (barley accelerating from cruising speed) and only happens in 3rd with OD off, or in OD with it on. It was rarely doing this before, but this morning on the way home from work, it was getting bad, and for the first time, did it at 2000 rpm on the highway, cruising speeds. The TC runs fine under medium to heavy throttle.
I do not believe it has anything to do with the BD tranny, BD TC, pressureloc, or Edge, as I was having this problem with all stock parts as well. After the new Tranny, this problem was gone. Could this be because I had removed the battery cables, and reset the PCM?
No codes. No limp mode. This is really annoying, and I'm sure is unhealthy for the TC.
I don't know where to start. Does anyone know anything about this? Happened to any of you?
Thnak you in advance for your help.
I do not believe it has anything to do with the BD tranny, BD TC, pressureloc, or Edge, as I was having this problem with all stock parts as well. After the new Tranny, this problem was gone. Could this be because I had removed the battery cables, and reset the PCM?
No codes. No limp mode. This is really annoying, and I'm sure is unhealthy for the TC.
I don't know where to start. Does anyone know anything about this? Happened to any of you?
Thnak you in advance for your help.
09-04-2009, 11:38 AM
#2
Registered User
Welcome to the DTR! 
First question.... cycling from lock to unlock in OD? An 02 should be locked full time in OD. Maybe actually searching between 3rd and 4th?
Second question .... "reset PCM"?? Maybe APPS?
IMO, anything is possible with an electronic trans at light throttle and low rpm (lugging the engine).
Does it cycle when under say 1/4 throttle .... driving thru the shift from 3rd to OD?
I'm a firm believer is locking OD out below 50 mph at all times. This keeps the rpms up. Truck will drive and shift better, have more power, and will avoid lugging the engine. I ry to keep rpm's abouve 1600 at all times.
Problem is probably electrical. Some have had good luck checking and cleaning all ground wires.
I would start with the easiest. 1- Have you reset your APPS? 2- Still on original...or older batteries? Have them checked. Low voltage can cause all kinds of idiosyncracies 3- Try TOTAlly disconnecting the EDGE box and see. A bad Edge box has caused many different scenarios in the past.
I can tell you that, at 160,000 miles I started having minor occurances like you mention ....searching and cycling. I never got a code but when I replaced the APPS sensor.... all was good as new. Bought HERE! But try easier 'stuff' first.
RJ
First question.... cycling from lock to unlock in OD? An 02 should be locked full time in OD. Maybe actually searching between 3rd and 4th?
Second question .... "reset PCM"?? Maybe APPS?
IMO, anything is possible with an electronic trans at light throttle and low rpm (lugging the engine).
Does it cycle when under say 1/4 throttle .... driving thru the shift from 3rd to OD?
I'm a firm believer is locking OD out below 50 mph at all times. This keeps the rpms up. Truck will drive and shift better, have more power, and will avoid lugging the engine. I ry to keep rpm's abouve 1600 at all times.
Problem is probably electrical. Some have had good luck checking and cleaning all ground wires.
I would start with the easiest. 1- Have you reset your APPS? 2- Still on original...or older batteries? Have them checked. Low voltage can cause all kinds of idiosyncracies 3- Try TOTAlly disconnecting the EDGE box and see. A bad Edge box has caused many different scenarios in the past.
I can tell you that, at 160,000 miles I started having minor occurances like you mention ....searching and cycling. I never got a code but when I replaced the APPS sensor.... all was good as new. Bought HERE! But try easier 'stuff' first.
RJ
09-04-2009, 12:37 PM
#3
Administrator / Scooter Bum
1st, Try cleaning the battery cables and terminals on both batteries.
2nd look for the PCM on the passenger-side firewall near the air cleaner.
(look for the multi-plugs)
Look for a small ring terminal under the right side mounting screw.
Remove the screw, clean the terminal and the mounting surface with sandpaper and reinstall, then trace to the other end of the wire (about a foot away) attached to the firewall then remove, clean, then reattach that end.
Take it for a drive.
Worked for me.
2nd look for the PCM on the passenger-side firewall near the air cleaner.
(look for the multi-plugs)
Look for a small ring terminal under the right side mounting screw.
Remove the screw, clean the terminal and the mounting surface with sandpaper and reinstall, then trace to the other end of the wire (about a foot away) attached to the firewall then remove, clean, then reattach that end.
Take it for a drive.
Worked for me.
09-05-2009, 10:24 AM
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Thank you, that is some good info to have. I pulled the grounds and drained the system, hooked the grounds back up and seems to be fine. I forgot about that little reset trick, but that doesn't mean the problem is fixed. I would like to know what causes that to happen.
09-05-2009, 05:49 PM
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Did cleaning the grounds affect the problem? Didn't for me. Had the same scenario you describe back in July on my 01: TC locking and unlocking. This was on a new ATS HD trans coming straight from the trans shop and occured with regularity on drive from WA back to OH. I had always had minor 3rd to 4th gear "searching" with OEM trans, which seemed to get worse with the ATS trans, but this TC popping back and forth out of lock was completely unsettling.
Guy at ATS emailed me the fix. Involved running a ground wire from APPs to PCM. I've tried to attach the PDF instructions (if it doesn't post PM me and I'll get it to you). Only thing, the last step has a wire being cut from PCM, once I did this the TC would not lock at all. So re-attached this wire, and everything worked perfect. No more TC lock/unlock back and forth, and no more back and forth on the 3rd to 4th gear searching.
It's definitely a ground problem, but this is the way to lick it.
Guy at ATS emailed me the fix. Involved running a ground wire from APPs to PCM. I've tried to attach the PDF instructions (if it doesn't post PM me and I'll get it to you). Only thing, the last step has a wire being cut from PCM, once I did this the TC would not lock at all. So re-attached this wire, and everything worked perfect. No more TC lock/unlock back and forth, and no more back and forth on the 3rd to 4th gear searching.
It's definitely a ground problem, but this is the way to lick it.
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09-06-2009, 02:45 PM
#8
Cummins Guru
Run a separate ground wire from pcm directly to the battery ground connection. Usually fixes problem, electrical noise from alt is usually what is causing this problem.
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