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Transmission Experts, have some questions.

11K views 16 replies 4 participants last post by  4timesT 
#1 · (Edited)
I'm having a problem with the transmission in my 06 Chrysler 300C 5.7 AWD and want to rule out some things.

Couple of weeks ago I started the car, the battery was a little low and struggled to start but it did start on the first attempt.

The ESP/BAS light came on and then when I put it in reverse and the tranny didn't do anything. I gave it some gas and then it banged into gear. Same thing when I put it in Drive. After some driving, it finally and violently shifted into 2nd and 3rd and then lots of chimes went off and it went into Neutral. I was able to coast and park. I started the car about an hour later and she shifted into Reverse and Drive and moved back and forth in the parking spot. My buddy towed it home for me using dollies due to the AWD.

Tranny's been stuck in limp mode ever since, only 1st (maybe 2nd) and reverse.


I got codes P0700 (TRANSMISSION CONTROL SYSTEM (MIL REQUEST) , P0730 (Incorrect Gear Ratio) and P0778 (Pressure Control Solenoid B Electrical).

I have changed the fluid and filter and then also siphoned more out and replaced it to flush the fluid some. Fluid level is good.

Oh, I also cleaned the 13 pin connector yesterday, there was some tranny fluid in there. I couldn't replace it because it wouldn't come out even after loosening the 7mm bolt. The bolt wasn't free spinning in the conductor plate like some have experienced, it was completely loosened and still the connector wouldn't come out of the tranny. Could be because the tranny wasn't up to operating temp and the aluminum case hadn't expanded enough to release the connector.

After cleaning the 13 pin connector, I haven't gotten the P codes again but the tranny is still in limp mode.

Couple of hours ago I went at it again and after checking for codes, the only one I got now is P0748 (Pressure Control Solenoid A Electrical).

I also checked the resistance of the solenoids by disconnecting the harness to the TCM and using pin 38 as ground and all the solenoids are within spec.

I then plugged the harness back in, turned the engine ON and checked voltage going to TCM, pin 29 pink/black wire, and got 14.4 volts. I then checked the Solenoid Supply Voltage, pin 38 solid yellow wire, and got 3.2V in Park and 6V in Drive.

I believe that I should be seeing 11-14V at pin 38. So I'm guessing either the Conductor Plate is bad or the TCM?

Now, could a sensor or module outside of the TCM, such as ABS speed sensors or module, PCM, ESP/BAS, be sending an erroneous signal and causing the TCM to command a lower voltage to the solenoids, thus forcing the car into Limp Mode?

Also, how do I do a HARD reset of all the modules, TCM, PCM, ABS, etc? I have disconnected the battery and kept the positive and negative straps connected to each other for a couple of hours. Is that the best method?

Thanks in advance.
 
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#2 ·
Not sure on this one almost sounds like something computer related got fried or glitched out...do you have a tuner for your car? You may be able to update your software if you do have a tuner...may not help but couldn't hurt. Did you have any trans issue at all before this? The incorrect gear ratio would definitely cause limp mode my best advice is to get it hooked up to a computer and find out what is going on for sure...with the amount of computer controls on these cars it is probably something stupid lol. I hope it is not any kind of major failure.
 
#3 · (Edited)
Thanks, I hope it's not mechanical as well. I can deal with tearing apart the valve body but I'm not yanking the tranny out on my back.

No, I don't have a tuner.


Today I checked for short circuits between pins 36 and 37...and all the other pins going from the TCM to the conductor plate. All were over 5 ohms as they should be. I tried borrowing Snap On Solus scanners from 2 guys I know but they weren't too keen on lending out a 10 thousand dollar piece of equipment. lol They both did offer to help me out if I brought the car over so that's what I'll try and do tomorrow. I want to use the Solus to reset the TCM DTC codes and also check the wheel speed sensors to rule them out.

Going by the troubleshooting procedure in the shop manual, the TCM is bad. But I want to make sure that the lower than normal voltage going from the TCM to the solenoids, isn't being caused by some outside module sending a DTC to the TCM, which the Torque Pro isn't able to detect. The Snap On scanner should be able to clear that up for me.


A while back the car would stall while in drive and pressing the gas to proceed after having been stopped at a red light. After restarting and putting it in drive, it would stall again. If I put it in reverse, it wouldn't stall and I was able to back up. The car left my wife and daughter stranded once, thankfully her dad was close by and picked them up. When I went to check on the car the next day, of course it ran fine and I was able to drive it home. But having already had it happen on a prior occasion while I was driving, I knew there was something going on. So the car sat while we used our other car.


Trying to troubleshoot these CAN bus cars, without the big boy scanners or throwing parts at them, is a real PITA! Dealer service departments have the equipment and can swap parts and rule out modules...but it'll cost ya and they're not always on the up and up. lol
 
#4 ·
Thanks, I hope it's not mechanical as well. I can deal with tearing apart the valve body but I'm not yanking the tranny out on my back.

No, I don't have a tuner.

Today I checked for short circuits between pins 36 and 37...and all the other pins going from the TCM to the conductor plate. All were over 5 ohms as they should be. I tried borrowing Snap On Solus scanners from 2 guys I know but they weren't too keen on lending out a 10 thousand dollar piece of equipment. lol They both did offer to help me out if I brought the car over so that's what I'll try and do tomorrow. I want to use the Solus to reset the TCM DTC codes and also check the wheel speed sensors to rule them out.

Going by the troubleshooting procedure in the shop manual, the TCM is bad. But I want to make sure that the lower than normal voltage going from the TCM to the solenoids, isn't being caused by some outside module sending a DTC to the TCM, which the Torque Pro isn't able to detect. The Snap On scanner should be able to clear that up for me.

A while back the car would stall while in drive and pressing the gas to proceed after having been stopped at a red light. After restarting and putting it in drive, it would stall again. If I put it in reverse, it wouldn't stall and I was able to back up. The car left my wife and daughter stranded once, thankfully her dad was close by and picked them up. When I went to check on the car the next day, of course it ran fine and I was able to drive it home. But having already had it happen on a prior occasion while I was driving, I knew there was something going on. So the car sat while we used our other car.

Trying to troubleshoot these CAN bus cars, without the big boy scanners or throwing parts at them, is a real PITA! Dealer service departments have the equipment and can swap parts and rule out modules...but it'll cost ya and they're not always on the up and up. lol
When it stalled out like that it wasn't right after a fill up was it?
 
#6 · (Edited)
Quick update. When I got 3-6 volts from the yellow wire in the harness going from the TCP to the 13 pin connector, trying to see how much voltage was going to the solenoids, I was checking the wrong solid yellow wire. Leave it to the engineers to put 2 solid yellow wires in a 12 wire harness. :doh:

So I measured the power going to the solenoids today, using the correct yellow wire lol and I got .1V. I also ohm checked the wire to ground and it's not shorted out.

Later in the day, I was able to use my buddy's Snap On scanner and it also showed .1V going to the solenoids and that the TCM has set the tranny to limp mode. Knew that already but it doesn't hurt to verify.

Both speed sensors on the conductor plate are getting 6V as they should (that's the other yellow wire lol) and both were sending a speed signal to the TCM.

The four wheel speed sensors (ABS) are apparently also working properly.

Reset all the DTC codes but P0778 keeps coming back and the tranny is still in limp mode. Looks like I'm going to have to pull the valvebody.

While doing more research online, I stumbled on a Tech Authority 722.6/Nag 1 Student Workbook. Similar to the Chrysler manual but has some more explanations.

https://techauthorityonlinedemo.extra.chrysler.com/service/mds2002/workbooks/en_US/8169903067.pdf

Hope it helps someone out! :thumbs_u:
 
#8 ·
Are you confirming measurements against the Factory Service Manual, or?
 
#10 ·
These cars do real weird things with low voltage. Have you ruled out your battery? Maybe borrow one if you can and see if that makes a difference.
 
#12 ·
I was thinking about that yesterday. I had charged the battery but it was still having a bit of a hard time starting her up.

Can a Snap On scanner completely erase the P0778 code from the TCM, so it releases the limp mode? Or do I need a the wiTech Micropod 2 to do it?
 
#11 ·
I assume you measured fluid level carefully / correctly (by the book)?
 
#16 ·
***** UPDATE *****


So after chasing my own tail, due to not following the service manual's instructions, the car is out of limp mode and shifting again. I also followed the directions of another member, who had also dealt with P0778 issue and after he changed the TCM to no avail, what worked for him was pulling the valvebody, tearing it apart, cleaning it up and reinstalling it. The tranny fluid in my car was pretty nasty so maybe something was gummed up in the valvebody. So I pulled the valvebody, cleaned it up, checked and cleaned the solenoids, bought a new conductor plate (even though I wasn't looking to throw parts/money at the problem). I reset the TCM codes (P0700 and P0778) using a wiTech Micropod 2 aaaaand the problem was still there.

If anyone reading this had seen my earlier posts, I had previously checked the resistance of the solenoids in the valvebody by measuring across the pins in the TCM harness as instructed by the service manual. If all the readings were within spec, which they were, then the manual instructs to replace the TCM. The section in the manual dealing with DTC P0778 is section 21, pages 94-97.


I wanted to update this thread in case anyone else was unfortunately dealing with this issue and to thank those who helped, especially BlackAce, who not only helped me with getting the wiTech Micropod 2 working, diagnosing the problem but he also gifted me a good working TCM.


Thank you again BlackAce!!!
 
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