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Discussion Starter #1
I've had the almost exact same experience as this thread:

07Sebring codes 700/765 looking for shop in Albany, NY area (at https://www.allpar.com/forums/threads/07sebring-codes-700-765-looking-for-shop-in-albany-ny-area.217841/ )

Didn't want to muddy that thread, so starting new one specific to my situation...

121,000 mi, transmission shifts nice and smooth, no slipping. New fluid/filter/flush 1 yr/5,000 miles ago (ATF+4), no leaks, proper level. PCM replaced with rebuilt unit 2 yrs.10,000 miles ago. TCM swapped with used unit 1 yr ago.

Got p0755, 2-4 solenoid circuit (only, no other codes)+limp mode. Like the thread above, seems random, sometimes 300 miles between codes, sometimes 5 miles.

Here's what I've done (still have the problem):
New Mopar Solenoid pack
New Mopar In/Out Speed Sensors
Thoroughly cleaned battery and body/trans ground connections
Swapped with old/original TCM

I suspect wiring or PCM.

Can anyone help with wiring diagrams or testing procedures to help solve this? Since the other thread was for a 2007 the pin outs are different. I can test resistance etc. but do not have access to oscilloscope.

Is it possible to swap wires at solenoid pack and PCM/TCM to rule out wiring, say swapping 2-4 wires with OD wires? Seems that would be more definitive if possible.

Any help is appreciated.
 

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Welcome to Allpar. The 2002 JR Transaxle Diagnostic Procedures manual is here:
http://oskin.ru/pub/chrysler-dodge/manuals/Service Manuals/2002_JR_Sebring_Stratus/02jret.pdf
The P0755 troubleshoot instructions begin on p. 70. The PCM isn't related. Wiring maybe.
Connector pinouts, wire colors and a simple wiring diagram are at the back of the book.
You will have to catch it while it is acting up or everything will look OK. Gently wiggling wire harnesses while testing continuity might offer clues?
 

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Thanks so much ImperialCrown! I will get on this tomorrow. In the meantime, I found a couple things:

A ground I missed earlier, above the evac solenoid on the inner left fender, mildly corroded, now nice and clean.
If I use autostick to keep it in 3rd gear, It seems not to go into limp mode, better than driving home in 2nd!

I suspected that I would have to catch it while it is acting up but I have no idea how I would do that. I will give the wires a thorough test tomorrow. I'm pretty sure that I can get the harness opened up from the TCM to the solenoids if needed to give them a good close look.
 

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I believe transmission diagnostic code P0755 is caused by excessive resistance in the wiring circuit between the TCM and transmission pressure solenoid pack assembly that controls the 2-4 solenoid. Excessive resistance is reducing the inductive spike in the 2-4 solenoid circuit when the solenoid is de-energized. The TCM monitors this and after several fault occurrences, is setting the diagnostic code and placing the transmission in limp mode / second gear.

Go to this link and see my post #26 dated Mar 3, 2019 and the discussion about inductive spike in transmission solenoid circuits.

07Sebring codes 700/765 looking for shop in Albany, NY area (at https://www.allpar.com/forums/threads/07sebring-codes-700-765-looking-for-shop-in-albany-ny-area.217841/page-2 )

. . . If I use autostick to keep it in 3rd gear, It seems not to go into limp mode, better than driving home in 2nd! . . .
I think this is a clue to the problem. This test may sound a bit strange but please bear with me. Select an area where you can start forward movement of the vehicle without shifting to REVERSE. Move transmission selector to NEUTRAL position. Shut off engine. Start engine and move transmission selector to Drive position. DO NOT ENGAGE REVERSE. Accelerate through the gears. Does the transmission shift into fourth gear / overdrive and hold steady speed and NOT go into limp mode? Post your test results.
 

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Discussion Starter #5
Hi AllanC, thanks for the info and help, it was all your insight on that other thread that got me here...This morning I pulled the wiring harness from the TCM to the solenoids and am removing all the black tape/wrappings from the wires to get a good visual on them. There are a couple points where the harness is pressed pretty tightly between components and if I'm lucky, I hope to find something obvious there. I am also leery about all the connection points, nothing looks obviously damaged (pins or corrosion or anything) don't know how to verify 100% though. Will be doing lots of resistance testing...and hoping I find something conclusive.

Since the car is apart right now, I will do the test you suggested later today when I get it back together and report back everything I find.

One immediate question though: am I really only focusing on 1 wire/circuit? (T19, 2-4 solenoid control) that goes from TCM pin #19 to solenoid pin #8? Is that like a ground that is controlled by the TCM in order to operate the solenoid? Does the excessive resistance have to be there somewhere and not on the 'power' side of the circuit? (I just have a basic understanding of this stuff, bear with me..)
 

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12v + is supplied from the EATX relay to all solenoids. The individual solenoids are switched on or off by the TCM switching the low-side ground in or out.
Look carefully at connectors or splices. They are the weakest link. Harness rub-through can also occur at sharp edges and vibrating surfaces..
 

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. . . One immediate question though: am I really only focusing on 1 wire/circuit? (T19, 2-4 solenoid control) that goes from TCM pin #19 to solenoid pin #8? Is that like a ground that is controlled by the TCM in order to operate the solenoid? Does the excessive resistance have to be there somewhere and not on the 'power' side of the circuit? . . .
Yes your attention should be focused on the 2-4 solenoid control circuit between TCM pin #19 and solenoid control pack pin #8. The TCM is monitoring this circuit for abnormal electrical current flow (excessively high and/or low) and reports accordingly.

When a solenoid is flowing electrical current a magnetic field is generated due to the circular winding of the coil inside the solenoid. When electrical power is interrupted / turned off, the magnetic field collapses. As a result there is an expected, momentary spike in the voltage on that circuit. If it is a 12 volt circuit, the spike is a multiple of this 12 volts. With excessive resistance, current flow is reduced so when the magnetic field collapses the spike will be proportionally less. The TCM is detecting this and setting the code P0755.

You do not have a ground problem. The TCM is controlling the ground for all of the solenoid pack circuits. If there was a ground problem you would have multiple error codes for other circuits to that effect. This is NOT the present situation.The resistance problem is on the load / power side of the circuit. You need to check all connectors for pin and receptacle mating (cleanliness, tight fit, etc).

In post #2 from contributor ImperialCrown he gave a reference to documentation for diagnosing transmission control issues. There is a companion reference or service manual for this vehicle which illustrates wiring diagrams. Review that and look in Chapter 8W - 31 - 7 for a wiring diagram.

http://oskin.ru/pub/chrysler-dodge/manuals/Service Manuals/2002_JR_Sebring_Stratus/02jre.pdf

Attached is an image of the wiring from the TCM to the solenoid control. Pay particular attention to connector C104 which contains the 2-4 control circuit. That could be generating the excessive resistance in the circuit.

TCM to Solenoid Control Pack Wiring.gif
 

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Discussion Starter #8
I appreciate all the help ImperialCrown and AllanC. I've been working on this all day, wish I had a big breakthrough to report, I don't.

I can not find any abnormal resistance.
I am now intimately familiar with connector C104! Its pins and receptacles "look" fine, and when its connected, I don't see any resistance change when testing from TCM to solenoid pack.

Is it possible that the problem is closer to the relay/PDC? I did swap relays (and a new one should arrive today or tomorrow), just wondering if a loose connection could can be under the relay, haven't figured out how to get the PDC apart yet though. I didn't explore that too much previously because I thought that if I had a problem on the power side, that it would be affecting all the solenoids (as you said for the ground side....so obviously I don't know much about this stuff).

For lack of other ideas, I just drove the car 25 miles in my garage. It was already up on jack stands, what the heck. shifted up and down through all gears throughout and repeatedly. Wiggled, jiggled, and fondled every wire and connector from TCM to C104 to Solenoid pack while the car was "driving". COULD NOT REPLICATE THE PROBLEM! No 2-4 solenoid circuit error. (on the prior test drive last night, code set within first 5 miles). The TCM "should" be doing its little check on the circuit every 10 seconds or after shifts, right?

So what do you make of that? Where would you go from here? I sincerely appreciate any additional thoughts.
 

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The DRBIII scan tool can show stored event data from the TCM much like a snapshot or freeze frame of other EATX parameters when the fault occurred. This could offer possible clues of what else was happening when the fault set.
Driving it with a 'co-pilot' or other data recording device would let you press a trigger button when the fault occurred (limp-in) and the device would record sensor inputs for the 90-second span leading up to the trigger button push.
Both these units would plug into the OBDII connector. Just tie the wires away from your feet.
 

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I appreciate any "informed speculation" or educated guessing about this problem, no matter how silly or far-fetched it may seem. Nobody's credibility is at stake here, what would you guess? solenoid pack? wiring? tcm?

Here's what else I tried: Car on jack stands, running, in 4th gear via autostick. With a hammer I gave a couple firm taps to each component to simulate hitting a sharp bump in the road. I tapped the PDC, the EATX relay, the TCM, the PCM, the C104 and C105 connectors, the solenoid connector, and the solenoid pack. To see if I could cause the p0755 code to set. No luck.

The only things I have not uncovered and investigated are two splices (S100 and S112) shown on page 8W-31-2. Do you think its worth removing the PDC and trying to find those splices?

I also don't have a test light needed to perform a couple of the tests from Post #2, I can go pick one up I guess...
 

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A homemade test light can be made with a 12v peanut (sidemarker) bulb and a couple of jumper wires with alligator clips at each end. A T-pin can be slipped into a connector to make contact with the terminal. Avoid piercing plastic wire insulation to check for power.
 

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I went through all of this and it will drive you crazy. In my case it was the PCM. I got a rebuilt one from Flagship One. It is still in service today. My mechanic had a scanner with an ocilliscope function and we could see the fields collapsing. If your wiring checks out chances are its the TCM. Buy a rebuilt one rather than used. We originally got a used PCM but it had the same problem as the one we were replacing.
 

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I will be making a test light as you suggested—I was literally just thinking I could try that...turns out that you can’t just go pick one up...all the autozone/advances have are LED type. Just wasted an hour on that.

Since I’m afraid of unseen/internal wire corrosion or loose connectors causing this problem, I’m being extra careful not to cause something like that for the future...that is if I don’t end up lighting a match to this DEMON.
 

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. . . .The only things I have not uncovered and investigated are two splices (S100 and S112) shown on page 8W-31-2. Do you think its worth removing the PDC and trying to find those splices? . . . . .
You have to develop a testing methodology that eliminates all possibilities one by one. So it can be tedious but you should leave "no stone unturned" and check all possibilities.

But first I would suggest that you check the resistance of each of the 4 solenoid circuits at the solenoid control pack. Remove the 8 pathway electrical connector at the transmission control solenoid pack. Touch 1 probe to pin #4, relay control power input to the solenoids, and in turn touch the other probe to pin #5, pin #6, pin #7, pin #8. These pins are respectively underdrive, overdrive, low-reverse and 2-4 solenoids. Resistance should be in the range of 1.6 - 1.7 ohms. Note if any difference between the 4 circuits.


Below is a link to a case study discussion about voltage spike and excessive resistance in the solenoid circuits.

https://www.motor.com/wp-content/uploads/TransmissionCaseStudies-June-2011.pdf

The discussion starts with general situations encountered with electronically controlled and electronic solenoid shifting. Starting on page 7 and later the discussion pertains to Chrysler built electronic control transmissions. Very good case studies about the expected solenoid spike along with graphs.

I will be making a test light as you suggested—I was literally just thinking I could try that...turns out that you can’t just go pick one up...all the autozone/advances have are LED type. Just wasted an hour on that. . . . .
You have to be very careful when using a test light to check for power and continuity on automobile circuitry. If you use an incandescent bulb such as a tail light or turn signal bulb and you use it to check for continuity on a ground side switch solid state circuit in a PCM or other electronic control module, the excess current flow ( 2 or more amps) can permanently damage such circuits. Many circuits within a solid state device are designed only for milliamp draw.

In those situations it is best to use an LED test lamp. LED bulbs only draw a few milliamps and are safe to use on solid state device circuits. If you KNOW you are testing a conventional circuit that is NOT controlled by a solid state device then usage of a larger amperage incandescent bulb will not cause a problem. But it really focuses that you have to KNOW WHAT YOU ARE DOING and the type of control circuit you want to test. If in doubt do NOT test for continuity or use an LED test lamp.
 

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CudaPete's 2007 PCM and TCM were likely both together in the same housing.
A 2002 may still be separate PCM and TCM modules.
For reference, on a 2002 JR 2.7L TCM, the Mopar reman # is R4896789AD. The factory OEM production # is 4896789AD. These part #'s may have superseded since.
 

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Discussion Starter #16
I'm still very appreciative of all the suggestions and help, and I am following all of the advice.

PCM/TCM: Separate units, Both purchased from FlagShip1, supposedly with lifetime warranties. I still have to old/original TCM that gives the same p0755. Also have the 1 year old solenoid pack that replaced when I first got this error.

Test light: Service Manual test procedure calls for incandescent test light to test for high resistance, indicated by dimming of the bulb. I have a digital multimeter to test continuity/resistance.

Methodology: I've been doing the same checks on the other solenoid circuits as I go, mainly out of curiosity to see if they give similar results, and I haven't noticed anything very different so far.

Solenoid resistance: the one thing I didn't check on the other solenoids! I will do that and report back. I can check four on new Mopar unit that is on the car and four on the pack I just pulled off (ATP TE-6).

Thanks again for all the help and insight!
 

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Thanks for the magazine article by the way, very insightful!

Here's what I found for the solenoid pack resistances:

New Mopar (on car):
4>5: 1.2-1.3
4>6: 1.3-1.4
4>7: 1.3-1.4
4>8: 1.3-1.4

Old ATP (on bench):
4>5: 1.2-1.3
4>6: 1.1-1.2
4>7: 1.1-1.2
4>8: 1.2-1.3
 

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Also relative to the article and electronics troubleshooting in general: My battery is good 12.7-12.8 volts, replaced battery and alternator 16 months ago, paid up for new Mopar alternator (not rebuilt). Also have excellent grounds to body, PCM, TCM, and transmission, getting less than 0.3 ohms resistance between battery negative and every ground I've probed--I checked all the grounds in the TCM connector, TCM/PCM casings, engine block, transmission, various points on body, etc.
 

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. . . . Here's what I found for the solenoid pack resistances:

New Mopar (on car):
4>5: 1.2-1.3
4>6: 1.3-1.4
4>7: 1.3-1.4
4>8: 1.3-1.4

Old ATP (on bench):
4>5: 1.2-1.3
4>6: 1.1-1.2
4>7: 1.1-1.2
4>8: 1.2-1.3 . . . .
Good test. So this shows consistency in resistance values of the solenoids both original and replacement. These values are slightly less than the 1.6 - 1.7 ohms mentioned in the reference article about inductive spike. So you can eliminate the solenoids as the problem.

. . . .Also relative to the article and electronics troubleshooting in general: My battery is good 12.7-12.8 volts, replaced battery and alternator 16 months ago, paid up for new Mopar alternator (not rebuilt). Also have excellent grounds to body, PCM, TCM, and transmission, getting less than 0.3 ohms resistance between battery negative and every ground I've probed--I checked all the grounds in the TCM connector, TCM/PCM casings, engine block, transmission, various points on body, etc. . . .
Very good. Leaving no "stone unturned" in testing. You are eliminating possibilities.

At this point I would reconnect the 8 way connector at the solenoid pack pressure assembly. Remove the connector at the TCM. Test the resistances for the wiring through the solenoid pack assembly and record. You will have to back probe for pin #4. See attached image.

TCM to Solenoid Control Pack Wiring 2.gif
 

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I went through all of this and it will drive you crazy. In my case it was the PCM. I got a rebuilt one from Flagship One. It is still in service today. My mechanic had a scanner with an ocilliscope function and we could see the fields collapsing. If your wiring checks out chances are its the TCM. Buy a rebuilt one rather than used. We originally got a used PCM but it had the same problem as the one we were replacing.
Given that I haven't found the slightest hint of a wiring problem, I contacted Flagship One to initiate a warranty claim and have them send me a replacement. Seems that may take some time to accomplish, so I will keep searching in the meantime.

My gut tells me its the TCM. All it takes is one cracked solder joint on that circuit board...

Thanks for posting your experience in detail, that is what got me here. I too will report anything I learn.
 
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