RKW221

Hi
2007 S550
Shifts nicely from P to R and D.
Shift from 1-2 only after several slippings and half a mile driving. No shifts past 2. In diag mode shifting manually shows target gear correctly but only to P R D 1 2. Trying to manually shift to 3 is not even showing 3 as a target gear.
Filter oil swapped and correctly filled at 45 C.
Adapted via Launch X431.

​​Cond plate swapped.
Valve body cleaned, very very little shavings. Didn't take out spring valves but checked tension and ball valves also.
One faulty solenoid swapped. All solenoids resistance tested. Nets pretty clean and looked ok. Magnet cleaned.
Car runs rough.
Tumble flap issue will be addressed.
Voltage too high on transmission error. Voltage regulator ordered for 910 option.
Rear battery drains. Teleaid coming out when MOST coupler arrives.
New ABS wheel sensors coming.

​​​​​TCU should have latest software.

Bought it really cheap at copart after two years of massive neglect. 140k miles. Project car as I was sad to see it rot....
Drive authorization on instrument cluster active after replacement.

Any ideas?
Thank you
Richard

JettaRed

iTrader: (1)

My understanding is that the solenoids and conductor plate are matched at the factory and cannot be swapped, though I have no confirmation of that. Do you have a history of the car?

Chevota

When my '99 did that it was limp mode because the tcu took dump. bought one on ebay for ~$200 and it was good to go. just needed to check if it was compatable, which the junkyard seller did for me

RKW221

Solenoids are adapted, no issue.
TCU new with the conductor plate.

​​​​​​Changed the valve body today.
Last chance voltage regulator, then it's a rebuilt transmission swap in the garage lol

CaliBenzDriver

Can you produce a complete scan report?
Limp mode condition should leave clues behind...

It sounds that your rough engine is in this for something, not just TCU not shifting out of 2nd.

RKW221

I will do that tomorrow if I have time. Moving day...

​​​​the only error I saw was tumble flap sensor related. I swapped one coil on cyl 1 4 weeks ago and changed spark plugs.
The under voltage at terminal 30 and the rear battery drain is an issue, but as I don't drive the car too far it's a problem. Will remove teleaid tomorrow, finally got the most bypass. Recode the most ring and we will see. Siren is out already.

I'm thinking of taking the trans out and doing a new clutch pack, but afraid there might be scoring on the shafts, bearing issues or sth else causing the probable low pressure to engage the clutches for the 2-3 and higher upshifts.
How different were the 722.9s from different models? Housing the same? Would swap my cond plate anyways, but not sure if a cls, gl 722.9 fits into the s550. I know the 722.9 came in different models numbers.
This is driving me a bit crazy.
I suspect the idiot previous owner had the working pressure solenoid issue that I fixed with the new cond plate but he drove the car with the clutches not being fully compressed and therefore worn them out completely. Is the shift from P to 1 done at a lower pressure than 2-3 and 3-4 etc? Just so I understand. Or is the pressure constant, just rerouted by another solenoid?
ISM no error, but that only shifts p-d-r I think. Correct?
Also the hood closed switch on 1 side was out, I ziptied it, no change.
How does limp mode behave? Does the car rev into 4-5k rpm but the transmission doesn't shift higher? Or are revs limited? But limp mode should show an error on the TCU, no? All I get is the implausible gear/slipping error.
I'll try to swap the voltage regulator tomorrow, but the working voltage when the car is running looks ok at 13.8-14.1V.

​​​​​​

CaliBenzDriver

Too many things wrong at the same time.
You need to prioritize to get results.

Your engine + tranny + chassis all need attention.

Chevota

The clutch pressure should be the same, I would assume, but MB likes to cut corners so maybe they thought they could net an extra billionth of a mpg by cutting pressure.
If the clutches were wasted you'd see it in the fluid and pan, which I assume you didn't. Unless maybe someone cleaned it, but they'd need to drain the converter to get all the nasty stuff out.
It would still shift into 3rd because it doesn't know the clutches are gone, but it's not even trying. That tells me TCU or some BS electronic part or something telling the TCU it should be in limp mode. So if it were me I would not pull the tranny yet. I understand the frustration, but what would the frustration be if you rebuilt it and the exact same thing happens. Your call, but I won't pull a tranz unless I see a reason. I do worry about the slippage you mentioned, but if the fluid was clean it makes me think TCU or some BS part again. Or perhaps fluid pressure is the problem? Maybe some solenoid or valve is bleeding it off?
The rev limiter will be in the ECU, but I do know mine (2016) does factor in what gear it's in. So I can have a different rpm limit for each gear, and one for P/N, which I do.

Sorry I didn't think of this earlier, but here's all the info I have that tranny: https://transferxl.com/download/00ZmH4VCZkfcP
Maybe of use, maybe not, but better than nothing. It's only worth five downloads so hopefully people will refrain and let the OP get it

RKW221

That is exactly what I am thinking and what I feel is the case. Not sure, but I suspect it.
In the many posts I read, the voltage regulator was one of these bs parts. Also the wheel speed sensors.
But limp mode should show up as a TCU error. No?
Also I swapped both screens, the tach and the command. Could a SCN coding be an issue?
The car has chronic voltage problems coming from battery drain of the rear battery. I will pull the teleaid module and recharge the battery outside of the car and see what happens.
I also have terminal 30 undervoltage. Cleaned the terminals, but I think that comes from the rear batt drain.

The fluid and filter were pretty clean when I pulled them, but I think that comes from the fact that the mechanic who worked on the car before it went to copart did a fluid / filter swap, so it's hard to tell how the fluid looked before.
I do suspect that the conductor plate error I saw when I got the car "working pressure solenoid defective" could have been the problem. Not enough pressure, idiot driving around, clutches under pressured but still engaging, leading to high wear of clutches and eventual failure.

But my car is not even trying to shift to 3. Not even a hint.
Still not sure about the rev limit and how limp mode behave. Can anyone tell me? What tells me it might NOT be limp mode is the crappy shift from 1 to 2. That should be nice, but on the other hand if due to the electrical issue the pressure doesn't build correctly, then it could cause it. But the oil pressure is built by the internal oil pump, so again confusing. I should have swapped those solenoids... But they show ok on the TCU and looked fine when inspected and measured with the volt meter. O rings looked ok as well.
Had a uhaul truck on Friday. Man, that things shifted so nicely, I was in awe and what a nice feeling to have a car that shifts properly and doesn't do 7 mpg lol.
Thanks for the link, downloaded all of it and printed for my car folder in the garage. I'm old school, so paper is my friend lol

​​​​​

RKW221

So reading through the webinar doc, the pressure is changing in the valve body.
Looking at the shift chart, the k1 comes into play when going from 2-3.
But, I don't have ANY error codes on the TCU, except "gear implausible, slipping".
That would point me to a mechanical fault.
The o rings on the solenoids-they looked fine, no cracks, but could wear cause this whole issue?
By now I can drop the valve body blindfolded, having it taken down several times now... Just replacing the stress screws is a pain every time i do this. Reused the last time the valve body came down. Torqued super carefully. Once the error is fixed I do a final drop and replace with brand new ones.
My logic with this issue is confused, worse than when wife has PMS...