05 vue with 2.2 & 4t45e
 

hello all, i bought this vue always heard saturns was a good car. its a 2005 saturn vue with 100,000 miles, not too bad. i knew i was going to have to atleast put a new timing chain due to timing guide. got it home, found big hole in oil pan. oh well, new engine. i found one out of a 2006 colbolt. bought it, as a precaution i put new timing, guides, water pump ect... runs great.... drove it, getting po700 and po757 codes... ok changed filter and fluid... by the way there was 13 quarts came out just from pan drop, omg... figured out how to check fluid in this strange sealed tranny.... fluid wasnt too bad, not burnt no metal... test it out, same 2 codes... bought 2 new solenoids, put in.... same codes.... racking my brain, HELP PLEASE ... confuzzled.

2005 saturn vue
2.2
4t45e trans
100,000 miles

Circuit Description

The 2-3 shift solenoid (SS) valve is a normally-open exhaust valve that, in conjunction with the 1-2 SS valve, allows 4 different shifting combinations. Refer to Shift Solenoid Valve State and Gear Ratio. The 2-3 SS valve is attached to the control valve body within the transmission.

The transmission control module (TCM) monitors the actual gear ratio, and compares the actual gear ratio with the commanded gear ratio. DTC P0757 sets under 2 conditions:
A stuck OFF 2-3 SS valve
A stuck OFF 2-3 shift valve
When the TCM detects a 1-2-2-1 shift pattern, then DTC P0757 sets. DTC P0757 is a type A DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0757 2-3 Shift Solenoid (SS) Valve Performance - No Third or Fourth Gear

Conditions for Running the DTC

No MAP DTCs P0107 or P0108.
No TP DTCs P0120 or P0220.
No ISS DTCs P0716 or P0717.
No OSS DTCs P0722 or P0723.
No TCC stuck ON DTC P0742.
No 1-2 SS electrical DTCs P0973 or P0974.
No 2-3 SS electrical DTCs P0976 or P0977.
The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
The Calc. Throttle Position is 8 percent or more.
The input speed is 150-6,000 RPM.
The output speed is 200 RPM or more.
The engine torque is greater than 40 N.m (30 lb ft) when 3rd gear is commanded.
The time since the last gear change is 1 second.

Conditions for Setting the DTC

The following occurs twice during the same trip:
The TCM commands 3rd gear and the gear ratio is 1.54:1-1.71:1, 2nd gear, for 2 seconds.
The TCM commands 4th gear and the gear ratio is 1.54:1-3.11:1, 1st gear, for 2 seconds.

Action Taken When the DTC Sets

The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
The TCM commands maximum line pressure.
The TCM inhibits 4th gear.
The TCM freezes transmission adaptive functions.
The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
The TCM stores DTC P0757 in TCM history.

Conditions for Clearing the MIL/DTC

The TCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
A scan tool can clear the MIL/DTC.
The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Diagnostic Aids
If you clear DTC P0757, and then cannot set DTC P0757 again, inspect for the following conditions:
Fluid contamination
Plugged fluid circuits
Restricted fluid circuits

hello again,

im not one to ever put any additives in a car but, last ditch effort... im thinking it could be sticky parts inside valve body. i bought 2 cans of sea foam tranny fluid today... put it in and ran through all gears slow... going to let it sit all night and continue tom... ill keep everyone posted, my fingers are crossed!

hello derf, nice to meet ya ... im hoping and prayin this sea foam works... next i guess ill take out valve body. my wife is really excited and wants this thing, lol it is a pretty looking suv. hoping i can get it going for her.

May also be band/clutch issue --see below

Condition
Some customers may comment on any of the following conditions:

• An illuminated MIL where DTC P0757 is found as a history code in the PCM or TCM.

• No 3rd and 4th gear.

• The transmission does not shift correctly.

• The transmission feels like it shifts to Neutral or a loss of drive occurs.

• The vehicle free wheels above 48 km/h (30 mph). High RPM needed to overcome the free wheeling.

Cause




This condition may be caused by any of the following:

• Chips or debris plugging the bleed orifice of the 2-3 shift solenoid (367). This will cause the transmission to stay in 2nd gear when 3rd gear is commanded and return to 1st gear when 4th gear is commanded.

• A 2-3 shift valve (368) or 2-3 shuttle valve (369) that is stuck, restricted and/or hung-up in its bore.

• This condition may also be an indication of a damaged 2-4 band or 3-4 clutches. This clutch damage may generate debris causing the 2-3 shift valve line-up to stick in the valve body bore and set DTC P0757.

Correction
• Inspect the condition of the transmission fluid for signs of overheat or a burnt odor. If either is noted, the transmission should be disassembled for further investigation and repaired as needed.

• Inspect the inside of the oil pan for signs of clutch friction material. A small amount of friction material in the bottom of the pan is normal. If a large amount of clutch material is noted in the fluid or bottom pan, the transmission should be disassembled for further investigation and repaired as needed.

• Inspect and clean the 2-3 shift valve (368), the 2-3 shuttle valve (369) and the valve bore of debris/metal chips.

• Inspect and clean the 2-3 shift solenoid (367B) opening of debris/metal chips. While inspecting the 2-3 shift solenoid (367B), look for a screen over the solenoid opening. If the solenoid DOES NOT have a screen, replace the solenoid. All current GMSPO stock shift solenoids have a screen over the solenoid opening.

• If clutch debris is found, it is also very important to inspect the pressure control (PC) solenoid valve fluid screens. Clean or replace the PC solenoid as necessary. It is also important to flush and flow check the transmission oil cooler using J 45096. Refer to SI "Automatic Transmission Oil Cooler Flushing and Flow Test" for the procedure.

Refer to the appropriate Service Manual for additional diagnostic information and service procedures.

sensors???
 

im wondering... there where 3 sensors in the old block that we didn't change to new engine. my question is could one of them sensors be causing the codes and not allowing it to shift into 3rd or 4th and if so why wouldn't i get a code for one of the sensors. the engine runs great and shifts fine from first to second. also, i believe the 3 sensors im talking about are all in same spot, in front on drivers side. i uploaded pic to site but cant see where to put in post. one is a knock sensor, and one is a crank position sensor and the other is just a screw in block on one end and a plug on other. UPDATE: The crank and knock sensors are the same but i cant figure out what the last one is.... it just a screw with a place for a wire to plug into.

2005 saturn vue
2.2
4t45e trans
100,000 miles

Symptoms of a Bad or Failing Transmission Oil Pressure Switch

Common signs include the vehicle entering "limp" mode, having difficulty shifting, and its engine RPM being higher than it should be.

think this could actually be the problem...

2005 2.2
4t45e trans
100,000 miles

may be a contributing factor, but the OBDII messages are VERY specific as to what the TCM and ECM sense are wrong.

I've outlined the exact situations that throw a P0757.

Now WHY it throws that code may have several contributing factors.

A failing tranny pressure switch may be involved, but I would think all the shift solenoids would somehow be affected.

No one wants to think that their tranny may have major internal issues, but the possibility should not be ruled out.

Lemme see if I can a pro to give an eval on the forum......

cool, and yes i know but im just trying to eliminate everything else before putting a dif tranny in or rebuild. also, i believe it is best to put all sensors from old engine in new block, i did not. also, i notice my oil light is barely on and in my thoughts im thinking now that it might be going bad or not a good connection. if the thing is working but a bad connection it might be telling pcm that it is working just not enough pressure to tell tranny to shift. i will be doing this tom. ill let yall know. also have not seen one other person with the same two codes as mine. it also dont and will not throw a code until i get to 45 mph. again ty

2005 2.2
4t45e trans
100,000 miles

fingers crossed....

Hey there Confuzzled

I doubt if your oil light issue has anything to do with your transmission problem. P0757 in an internal performance (Slipping Code) inside the transmission, during the 2-3 up-shift, and has nothing to do with the engine performance, or operations of the engine.
The computer monitors engine speed, input and output speeds at the transmission, TPS and engine coolant temp to control shifting. When the input and output speeds don't fall within a set parameter of programmed tolerances for each commanded gear, performance codes will set. Code P0757 will set for the 2-3 up-shift malfunction. The computer is commanding 3rd, but the gear ratio (input and output speeds) determined that it didn't make the shift.

If the vehicle free wheels above 30 mph, and higher rpms are needed to overcome the free wheeling. This condition may be caused by any of the following:

Chips or debris plugging the bleed orifice of the 2-3 shift solenoid. This will cause the transmission to stay in second gear when third gear is commanded and return to first gear when fourth gear is commanded. This can be confirmed by observing scanner data while driving the vehicle.

A 2-3 shift valve or 2-3 shuttle valve that is stuck, restricted and/or hung-up in its bore inside the valve body.

This condition may also be an indication of a damaged or slipping 2-4 band or 3-4 clutches. This clutch damage may also generate debris causing the 2-3 shift valve to stick in the valve body bore and set DTC P0757.

Inspect the condition of the transmission fluid for signs of overheat or a burnt odor. If either is noted, (as you said) the transmission should be disassembled for further investigation and repaired as needed.

I hope this information gives you a better understanding of the issue you are dealing with. If you have any other questions or concerns, please feel free to ask. We are all here to help, learn and understand. Please let us know what you decide to do.

Best of luck to you my Saturn Brother.

You are not alone in the P0700 P0757 code land.

Most of the info I posted I found by searching P0070 P0757 saturn as a single phrase. Especially the post about possible clutch and band issues., and what specifically sets the P0757 code.

I am completely confused about your oil light comment.
If you mean the oil light on the dash, it better NOT be on while driving, dim or otherwise. That light is for ENGINE oil pressure, not tranny fluid level. Nothing to do with tranny fluid level, pressure, ......

What is engine oil level?

Possible bad oil pressure sender, or failure to develop proper oil pressure which means internal engine damage is occurring.

Or the bulb is old and coated internally. Or got half knocked around and is loose in dash,

How bright is the oil light during key on bulb check without starting engine?

And that 13 quarts just in the tranny pan can't be right unless some moron found out it would sometimes shift if they over filled it some. SO they kept adding...and adding....

Hey Alpha -- great to see you!

Thanks for stopping by to help out with this one.

(Alpha is the pro I mentioned) -- professional transmission DUDE.

Alpha's word is based on years of professional personal experience.
I take his word as gospel.
Up to you as to how much faith you put in it.

--------

I would check out the oil light thing before you have someone rip into the tranny, since if the engine has internal damage from oil starvation, it may be more cost effective to junk this ride and begin anew.

Keep us updated

hello alpha...

no the engine is not junk, it was just put in... and please read this and tell me what you guys think...

https://www.yourmechanic.com/article...ressure-switch
this looks exactly like my switch i took out of old motor

and i agree derf.. i can find many post of codes but im talking about the combination of po700 and po757 together and only them that i find unique. and yes, someone didn't understand how to check that fluid, lol
also was my first sealed transmission so i did the research before i changed filter & fluid so i could make sure proper amount was in it.

Hey there Confuzzled

Yes, that switch looks similar to an engine oil pressure sending unit, sensor or a switch for the warning light. It actually does the exact same thing as an transmission pressure switch in some transmissions. It either turns on a warning light, or sends a signal back to the computer. Unfortunately the 4T45E has no external sensors except for the output speed sensor. My guess is that you pulled that sensor off the motor, not the transmission. I have provided a link showing what the electronic pressure control solenoid (EPC) #312 and the manifold pressure switch #13 look like. The manifold pressure switch tells the computer what range the transmission is in, like park, neutral or drive. The EPC solenoid varies pressure according to several factors like engine temp, and engine load for example, to control the quality of the shifts. Under heavy throttle it boosts line pressure for a harder shift. If either one of these sensors had a problem, you would have different codes, and different malfunctions, such as harsh engagement, and a flair on the 1-2 shift, or a really hard shift on the 1-2, before the code sets and the trans goes into limp-mode / fail-safe. Now I'm not saying you didn't replace the EPC solenoid when you had the side cover off the transmission to replace the shift solenoids...I'm saying it doesn't look like the sensor in the link you provided. That sensor has threads on the end, all the sensors on your transmission bolt in with a bracket.

GM's 4T45E Transmissions: The Good, Bad And The Ugly

There have been issues with the manifold pressure switch, but I have not seen one that just sets a code at 45 mph. At 45 mph, the computer should be commanding 4th gear. I would recommend taking this to a transmission shop, where they can drive the vehicle while observing the scanner data to watch command gears and ratios. Shift points under normal acceleration; 1-2 shift at 10 to 15 mph, 2-3 shift at 25 to 30 mph, 3-4 shift at 40 to 45 mph.

Most transmission shops like Cottman or Aamco will do a free road test and evaluation. Call around to make sure, and you will most likely need to leave the vehicle. If you wait, you may not get an accurate diagnosis because they are hurrying to get you an answer, instead of taking their time and researching the problem. I will tell you though, most shops won't try to patch a problem transmission with 100,000 miles, everything else is worn out inside it. Anything over 100K has reached it's life expectancy anyway, as far as American built transmissions go (Ford, GM, and Chrysler). That's why no one warranties transmissions for over 50K, way too many parts that wear out.

Now, about that oil light? When does it come on? I would guess at idle, sitting at a stop, after the engine warms up a little. This could be caused by a host of problems from a faulty sensor, too low of an idle at a stop, internal engine issues like a worn or damaged oil pump or sludge build up in the oil return passages. You were on the right path with replacing "all" the sensors off your old engine. Although it's the same engine size, you are using it in a different application, with different perimeters inside the computers. I would replace all the sensors, including the idle control solenoid and TPS if it has one. The MAP and or MAF, any EGR and EVAP sensors too that are attached to the old engine.

After that I would clear the KAM, (keep alive memory) using a scanner, and re-learn the idle control solenoid. At the very least, replacing the oil pressure sending unit would be a good place to start. There may be more that one. Some send a signal to the computer, some to a warning light. Do you have any other codes besides the p0700, which by the way, is just a code the TCM sends to the ECM to turn on the warning light, and to let you know there is a code stored in the TCM...code p0757. P0757 being a 2-3 shift performance code, could be mechanical or hydraulic, ie (clutches, bands and/or valve body) If it was electrical, it would set other codes.

Let me know when that oil pressure light comes on. And exactly what the trans does at 45mph, does it down shift, or free wheel like it's in neutral?

the light is just barely on like its being lit up by surrounding lights, its white light not red so might not mean anything... the only two codes im getting is po700 and po757. the suv runs great and shifts nice from first to second.then just high rpms at 45 and engine light comes on. if changing that pressure switch doesn't help im going to look at rebuilding or buying a re-manufactured one. just eliminating everything possible first. did u look at that link... and yes i did take it out of block... its located right above starter, but what i was thinking with electric trannys is it can take info from all sorts of places, like the oil switch on engine... been trying to find someone that knows if that particular tranny does???? and i was thinking the valve in valve body might be stuck.... when i drained fluid and dropped pan it was pretty damn clean... just brown fluid, not burnt, no metal... i changed solenoids in side cover, it all looked clean, just a few peices in fluid that looked like it was gelled but it was cold also.

critical for comparison to behavior of light with car running.

its red when u just turn key on, but after starting its faint white like its being lit by surrounding light

what im trying to find out is if that tranny gets info for shift from that oil switch or if it detects low pressure if it will put tranny in limp mode... any suggestions where to look???

Does the oil light intensity flicker with changing rpms? In Park?
Does the "vehicle running" appearance match the "car not running no key in it" appearance?
Does the intensity of the oil light change when the headlights are turned on and the dash is lit up?

I'm not trying to nitpick you to death, I'm trying to help you determine if the thing is really lit.

Typically the telltale/idiot lights are isolated from the dash light bulbs and also spaced from each other and masked between them so that light from other sources cannot enter the area that the actual bulb occupies.

I am pretty sure these lights are either on or off as they are triggered by a limiting lower pressure value stored in the PCM /BCM which, when reached, closes the ground on a 12V circuit which lights the bulb

But I am not POSITIVE.

I would have the oil pressure tested by a shop where they put a known good pressure sender in and measure it directly (not through the computer).
Even if you were to pull the dash to get to the instrument cluster, a faint glow still doesn't tell you if the pressure sender is good or not

As far as the oil pressure dropping low and throwing the tranny into limp mode---highly doubtful.
Even if it did, as long as the engine was turning you'd be damaging the engine internals and something would eventually give.

Limp mode can be triggered by the tranny self diagnosing -- as it has in your case -- but your P0757 requires a very specific shift sequence to occur repeatedly in order to set this code.

When a very specific problem is determined via self diagnosis by the TCM, it will set a very specific code.

Limp mode is a term that people use to cover 2000 possible different issues that make the tranny or engine go into failsafe mode
Each type of failure that occurs results in DIFFERENT actions taken by TCM, BCM, or PCM.
So although the performance is reduced, the exact nature of the problem dictates what the vehicle does to protect itself from further damage

i am going to change and test the oil switch tom. anyways, i just want to know if the tranny gets info from the pcm from that switch is all...

I think that transmission will run down the road in high gear and not care if the engine runs out of oil.

lol, these electronic trannys can be very finicky, i believe the engineers are not even sure what all they will do in certain cases.... that one link wasn't posted until 2016 so... im just trying to learn as much as i can as with anything im doing... some e trannys wont even let the car start if the oil pressure gets low... my bro-in laws tranny would go into limp mode after disconnecting stereo, some are connected to cruise control, very strange these are... im going to get me a 57 chevy with a straight 350, very few wires .... YEA... A 57 Chevy cherried out, my dream car

In theory it is possible

On a 2005 Vue -- in 2005 -- on a Vue ---

I highly doubt there is any info about engine oil pressure sent to the tranny; it should be going off its own fluid pressure among other things to know when to shift.

There are too many situations that could result in changes in oil pressure to determine what the tranny should be doing, especially when so much other definitive info like engine rpm, vehicle speed, MAP/MAF info, input shaft speed, and the slope of those values.

that's what im trying to find out derf... if the pcm/tcm gets any info from the oil switch that would effect that particular tranny... searching searching

also wondering if a faulty pcm/tcm could be the culperate... they are on same computer on this model...

also something very weird.... when u start the suv, i hear a bump bump bump sound.... sounds like its coming from rear somewhere then it stops... only 3 times... never seen this before either but might shed light or ring a bell for someone. when i first heard it i thought it was someone messing with me outside like they was hitting side of car... tap tap tap shut car off, start again... after a few seconds, again, tap tap tap

This is out of my Fsm.Attachment 1467

I hate to say this but engines blow up some times because transmissions don't shift into higher gears. You may have a pre-existing condition.

awesome 02 LW300, low high pressure? what does it say about that? how do i check that? yes i figured that, the engine was blown and i believe the tranny had something to do with it. the rod shot through bottom of oil pan... reason i put new engine.

i only paid 400 for it, engine for 200, timing parts and water pump 100, so its worth still fixing... i also already replaced a and b solenoids so thats ruled out.... whats getting me is that the pan and side cover of tranny was pretty damn clean, fluid was brown but not burnt... it was way overfilled, thats for sure... any simple things in tranny that could of got messed up because of it being so overfilled.... i got 13 quarts out of pan drop... wow

I think they hold 7.5 with the filter change. The trannys are pretty cheap because they hardly ever fail. I even have an extra 03 tranny that I'm sure is good. I paid $100 for this car, I just wanted the engine but i saved a bunch of parts including the tranny. This car worked fine until it had an off road adventure!Attachment 1464

cool, the colbalt i got engine from was wrecked but it was driven in and they heard it run... if i would of known this from beginning i would of just took engine with tranny, not sure if it would of worked without getting ecm/pcm flashed.
lol it had 5 extra quarts, i put 8.4 in before i started getting the dripping out of hole but it sat for over 24 hours draining so figured was ok.

The Vue has a lower final drive ratio than the cars. You need one out of an HHR, a G-6 or a vue. Check with the wrecking yard they will have an interchange listing.

far out, groovy, bitchin even.... so do u have any ideas about this tranny of mine? do you think taking valve body out and just cleaning and putting new seals in would be the way to go of just get a dif tranny?

Wow! Good job 02 LW30!

Direct from the Factory Service Manual! I see no mention of an oil pressure sending unit or PCM/TCM in the "Possible Causes" sections. This should without a doubt answer Confuzzled last two questions. Well, except for the thump noise. I will address that too...

Okay there Confuzzled:

In the manual 02-LW300 posted...To check the first two, low line pressure and TFP manual valve, you will need to attach a pressure gauge to the line pressure port on the transmission...I still recommend a transmission shop for this procedure as you will need a pressure chart for all the different ranges, and a tap chart for the right pressure port, if you have a 300psi gauge, you can find the info on line, or in a Factory Service Manual, or ask 02-Lw300 as he has that information too.

The next two possibilities you already addressed by replacing both shift solenoids.

Everything else is internal, and the valve body or trans will have to be taken out and dissembled for inspection to pinpoint the exact cause of the malfunction.

I can assure you that oil pressure will not affect the operation of the transmission. Although it can affect engine operation. Yes, on some vehicles, the fuel injectors will not pulse (squirt fuel), ignition system will not fire (provide ground for the coils to fire the spark plugs), and/or the fuel pump will be disabled until the PCM receives the proper oil pressure and/or crank sensor signals. These will set a code for low or no oil pressure and/or no ckm (crank shaft position sensor) signals.

You may be on to something about the oil warning light transfer. As per my experience, all the dash light bulbs are clear. There is a colored film/lens between the bulb and the outer lens. Like your turn signals don't have green bulbs, there is a colored film that makes them look green. Warning indicators have a red or orange film, and the high-beam indicators usually have a blue one. You said the warning light is red when you turn the key to the accessory position or "on", then is white after starting the engine. I have a simple test that will help diagnose this problem, I think Derf also recommended this.

Turn your ignition on, but don't start the vehicle, after the gauge cluster does it's bulb check, and all the warning lights go off, leave the key on without starting the engine and see if the warning light is white? If your headlights are not coming on, you may need to turn them on and see if the warning light is coming on then? I have seen a few cases of bulbs staying on too long, or the wrong bulbs used as replacements burning through the plastic, and illuminating other indicators. Depending on where the color film is located, this my very well be your problem with the oil pressure or oil level warning light.

Okay, the last, and very least of your problems, haha. The 3 Thumping Noises. Does your Vue have rear heat and or rear A/C? If so, it is most likely a HVAC blend-door malfunction, caused by an broken or out of calibration actuator. You will need a scanner, not a "code reader" to check the BCM for codes, and to check the operation of the rear HVAC actuators. Repair cost is minor compared to a transmission rebuild or replacement. Noise from the rear, will have nothing to do with the front mounted transmission. Good to cover all the bases though.

Now I understand we are all throwing a lot of questions and tests at you, but please don't be discouraged. We are all professionals here, or at least like to think so, haha. Without getting our hands on this Vue, we have to rely on you for answers. This is not always the best way to diagnose anything, but we can certainly narrow down the possibilities if given the proper information...and given..."the rest of the story." LOL!

I see several posts before I could finish my reply. Last question, replace or repair transmission. If I spend 6 to 8 hours pulling and installing a transmission...I want some type of warranty! Go with a used one, under 100K miles, out of HHR, a G-5 or a Vue as 02-LW300 recommended, make sure it's also the same engine (2.2).

Please...let us know what you find out, or decide to do.

i will def let you all know what i decide to do, but im def going to keep it for her "THE BOSS" lol like i said i already have a great engine installed and put the new timing and water pump in, runs like a champ so def worth putting a tranny in.... i am leaning on a stuck valve behind solenoid "B" so im still going to give the sea foam a chance... going slowly through all the gears slowly and driving it around the hood at a reasonable pace for a few times this week... u never know... if there is a restriction, it is worth a shot to me to give it a shot, its already in there now... i have Hope! AND THANKS TO ALL OF YOU FOR THE HELP, I appreciate it

Okay Guys, I missed one.

If the pan was clean...at 100K, someone has serviced it, cleaned the pan, installed a new filter and put in new fluid before the engine blew-up, trying to fix the exact codes you found. Most likely overfilled it because of no dip stick and didn't know how to check it. At 100K, there will be black soot in the pan, with some sparkling brass floating around, and a somewhat fuzzy magnet. Although these units aren't as dirty as say a TH350, or a 4L60E they do generate some degree of material, especially at 100K. If the pan was clean...someone has already been in there, based on my 35 years of experience.

Most people never service a transmission...until there is a problem! Never go 100K before a service as the dealerships/manufacturers recommend. I recommend every 30K. The manufacturers say 100K, because they know it will be way out of warranty, and they want you to buy a new trans from them. Most aftermarket re-builders will recommend a trans service at 25K to 35K for their warranty disclaimers. Doesn't matter if it "is" or takes Dextron-6/full synthetic, still recommend 30K no matter the recommendation of desired fluid. For GM, anything 06 and newer takes full synthetic or Dexrton-6. I believe they are recommending that for everything now, no matter what year it's built.

As far as being way over full, I have seen owners fill there transmissions to the top, by that I mean up to the top of the fill plug without any internal damage. What they will do is leak from every orifice on the transmission, and gush fluid out of the bell housing and fill plug. The fill plug is also the vent on GM transmissions without a dipstick. The fluid expands as it warms up, with no place to go, it takes the paths of least resistance. To simply answer your question, overfilling it will make a mess, but I have not seen internal damage caused by it. If some valve body ports are unable to vent fluid pressure, it could affect operation, but not permanent damage. Once the proper level is achieved, they work just fine, based on my experience.