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Discussion Starter #1
I recently purchased a new to me truck. It is a 2008 ram 2500, automatic. I've had it about 3 weeks now. Started out fine. Then driving on a on ramp into a highway I got on it a little bit to get up to speed, and the truck hit 5th gear, then slammed back into 4th gear and stayed in 4th.
I was upset this happened. But pulled truck over, shut it off and restarted it and it took off again like nothing happened.
Upon reading I found out the transmission went into limp mode locking it in 4th gear.
Then I drove it the next day and it went in limp mode again.
Then it hasn't done it for 2 weeks. Then last night I hop in my truck to drive to work. It was raining outside. So i pulled out of my driveway it shifted into 2nd, then right into 4th..
Ever since the first time it went into limp mode I've kept a code scanner in the truck. Everytime it goes into limp mode, it does not illuminate the check engine light. But if I check it, it does have a inactive p0882 code. Which is saying tcm power input low.
I noticed all my battery connections were really dirty and corroded. So I started with cleaning battery terminals, and the grounds onto the fenders. And also pulled positive wire off tipm and cleaned that as well. But still having this intermittent issue.
Naturally the previous owner mentioned nothing of this nature, and says it never happened to him (go figure)
Where else should I look, and or check?
Any information would be beyond helpful with winter approaching, and I'm not gonna be happy with this issue during the time I need the truck the most.
 

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You need to pull the codes from the tcm. Pretty sure your overdrives are done. Tuned with a heavy foot?
 

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Discussion Starter #3
Why do you think overdrive is gone? This just randomly throws a low voltage input code. Trans shifts very firm and solid. No slipping
 

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Why do you think overdrive is gone? This just randomly throws a low voltage input code. Trans shifts very firm and solid. No slipping
No slipping? It won’t let you use them you said. Going straight to 4th is protection mode. Hope it’s electrical for you, but you asked. Are you tuned?
 

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Discussion Starter #5
no trans does not slip. very solid and firm shifting (when it doesn't go into limp mode) in the 3 weeks ive had the truck, and 1,000+ miles ive put on it, its only gone into transmission limp mode 3 times. which then, it will go into 4th gear and stay, until i pull over, shut truck off and restart it. then transmission is back out of limp mode. when it goes into limp mode, i check codes(before i restart the truck), which there is no illuminated check engine light during this time, but it will have a inactive code which is p0882. my reader will tell me if its a active code (illuminated check engine light) a pending code, or inactive but stored in history. every time it throws the p0882, it is a inactive code. so that tells me what ever is happening is happening very intermittently, just enough to throw transmission into limp mode, until the truck is restarted, and it clears itself.

i was told when i bought the truck the transmission was rebuilt at one time, and claimed it had a billet input shaft, and a triple disk convertor, but no paper work to prove this. fluid is bright red, and clean.
the truck is deleted, and was told there is a 40hp tune in the truck, but i dont know if there is anything done to the transmission tune wise either.
 

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Probably some good info here on diagnosing/testing the P0882.

I know when I had mine go in limp mode the first thing I did was pull the pcm connector and check/clean and re-connect. Mine inevitably was a bad solenoid she I replaced the solenoid pack. If you’re is a low voltage issue then it could be a corroded wire going to the connector at the trans. The info below should help diagnose if you have a multimeter.

https://gearsmagazine.com/magazine/bypass-the-tipm-to-test-code-p0882/
 

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Discussion Starter #7
Probably some good info here on diagnosing/testing the P0882.

I know when I had mine go in limp mode the first thing I did was pull the pcm connector and check/clean and re-connect. Mine inevitably was a bad solenoid she I replaced the solenoid pack. If you’re is a low voltage issue then it could be a corroded wire going to the connector at the trans. The info below should help diagnose if you have a multimeter.

https://gearsmagazine.com/magazine/bypass-the-tipm-to-test-code-p0882/
That's some Amazing information. But they're testing on a 545rfe. Do you or anyone else happen to have the pin diagram for the 68rfe?
 

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Discussion Starter #8
Transmission went into limp mode again on my way to work Tonite. checked codes before i shut truck off. Same low input voltage code. But Tonite it threw a p0750 code as well. From what I've read, that requires a new solenoid pack to fix the 2nd code.
But I don't know if that code is happening due to it having low voltage or not. I would think low voltage would really mess with things
 

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Discussion Starter #9
I guess another question I have is this is detecting low input voltage to the tcm.
Is that low voltage from the tipm to the tcm, or low voltage from transmission to the tcm?
 

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It is from the TIPM to the pcm. Code set when detecting under 3V.
If you disconnect C4 on the pcm and the C1 on the TIPM you can measure resistance on the pin 18 (C4) to ground. Tell you if there is a shortcut.. And resistance between pin18(C4) and pin 10 (C1)Should not be over 5 Ohm. At least that way you can confirm the cables are intact.
 

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Discussion Starter #11
It is from the TIPM to the pcm. Code set when detecting under 3V.
If you disconnect C4 on the pcm and the C1 on the TIPM you can measure resistance on the pin 18 (C4) to ground. Tell you if there is a shortcut.. And resistance between pin18(C4) and pin 10 (C1)Should not be over 5 Ohm. At least that way you can confirm the cables are intact.
I'm getting confused between the ecm, pcm, and tcm. So many threads and posts contradict each other. Am i checking the pcm ( the one on the engine block?) Or the one on the passenger side of firewall?
 

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Sorry ;) PCM (powertrain control module) and TCM (transmission control module) Is the same thing, different name. The one on passenger side firewall.
 

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Discussion Starter #13
Sorry <img src="http://www.cumminsforum.com/forum/images/smilies/wink.gif" border="0" alt="" title="Wink" class="inlineimg" /> PCM (powertrain control module) and TCM (transmission control module) Is the same thing, different name. The one on passenger side firewall.
Can you help me with identifying which plug is which?
That post earlier describing how to diagnose this code was for a gas, 545rfe. Don't know if that'd make a big difference.
 

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I will try, but i am not sure I'm leading you to the problem. I am away for work so I can't give you any pictures and I trying to remember from the head ;) C4 is the lower contact on the tcm (firewall). should be a green mark on it. When you look at the connector you have a number of each side of every row, there you want number 18. On the backside on the tipm you have 4 big and 6 small connectors, and the second small from the top is C1. In that connector you should find numb 10.
For some reason I can't open "gear magazines" website but I think sometime ago they did a report on this problem with a more complex way to find the fault, maybe worth looking for that.
 

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Discussion Starter #15
I found the plugs, just having issues figuring which pins to check.
 

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Ok, then if you look at the plugs they are numbered. So C4 numb 18 and C1 numb 10 are easy to find.
 

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Discussion Starter #17
Finally got the chance to dig into this being as the rain has let up. Neither of the 2 plugs are numbered, on either side of them. So that makes it difficult for me.
 

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Discussion Starter #18
This is on the pcm

 

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Discussion Starter #19
And this is c1 on tipm

 

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Sorry about that.. I was sure they where numbered.
If you look at the C4 connector with the lock pointing up the upper row start with 1 on the right and 10 on the left. Second row start with 11 on the right and end with 19 on the left.
If you look at C1 lock pointing up, upper row start with 1 on the right and end with 7 on the left.
Second row 8right-14left
 
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