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Registered 2002 R170 SLK V8 5.0
2,627 Posts
Hi @BaD_81 ,

OK That's not the worst I've seen, but someone may have already tried an Oil and Filter Change to try and fix a burnt out Trans to no avail :(

But lets not get ahead of ourselves, yes it needs an Oil and Filter Change, I'd do the Connector Plug at same time, buuuuut ..................

Lets find out why it is in Limp Mode first, disconnecting battery etc will not clear a Hard Limp, a Soft Limp will clear on Ignition Off, Restart, so you do have the Former ;)

Get it on SDS, I want to see if it has Slipping Codes, (Ratio Errors) :wink:

I'm not sure how many of the cheaper machines will actually pull these Codes, I can confirm that Snap On will if you can't find anyone with SDS ;)

I'm still hoping for you that it is just the (common) Speed Sensor failure which causes this ;)

HTH, Cheers Dave

Registered 1998 SLK230K
46 Posts
Discussion Starter #42
Hey All,
Hey @Dave2302
Update from today (plus lots of wasted time googling/e-mailing garages near me for 1998 diagnostics).
With the cheap BT OBD diagnostic I received disk and few diagnostic apps.
One of them successfully deleted the errors!
However there will be not more than 3 starts and I will have them recorded again!
What I felt during the process is low revs (visible on the pics), the thing is it didn't raise the revs when I started it, yes it is not 10 degrees out but still it is a cold engine... I find it strange!
The other thing is I disconnected the TCM and almost, almost measured the Transmission Range Recognition Switch (TRRS).
Almost as the probes of my multi-meter are standard and the connector slots are as wide as a credit card is thick!
The TCM board looks like NEW, the capacitor has not been "impregnated" and I don't think there is problem with it (true I haven't checked in under microscope) the cabling under the plastic cover (beneath the carpet) as much as I could reach are dry!
So if wiring diagrams are available (even block-diagram) will be of help!
I hope the pictures are going to be clear/visible!


Registered 2002 R170 SLK V8 5.0
2,627 Posts

OK I looked at the jpg's.

Problem we have here is that it appears that you are only seeing stuff in the Engine ECU, which is why, to be certain, the Car needs a decent Diagnostic on SDS, there may well be other codes etc that you are simply not seeing.

Cheap / Free Apps, OBD Readers etc are not going to cut the mustard on this :wink:
Anything that costs less than a basic 拢400 SDS System is a waste of time and money on a fault like this :(

A couple of questions ............

When you reset it, did it shift gears properly ?

Are you actually seeing the Transmission Controller Unit info / codes, if so are they just Speed Sensor ?? ............
I have an educated guess that the Speed Sensor Codes in your picture are just CAN Communicated from another ECU to Motor ECU, it is a generic code and therefore it could be any speed sensor on the Car, likely Trans or ABS.

If ABS, ASR / ESP is not lit up when driving then could be a Transmission Speed Sensor ;)

I hate IF, COULD, MAYBE etc :wink:

An interrogation of TCU Live Data and ABS Live Data would confirm exactly which Sensor, otherwise you are just guessing.

It is looking like it may be just the Trans Speed Sensors on Conductor Plate, but I keep repeating myself, Car needs a proper Scan on decent equipment, preferrably SDS and also Data Interrogation, then we will know exactly what is wrong and avoid expensive mistakes ;)

There is absolutely no point in putting new parts in a Transmission that turns out to be slipping and thus requires replacement with a known good unit, or a professionally rebuilt one.
Even after all that it could just be a broken wire in ABS Sensor wiring .............. Can you see what I am saying here ;)

HTH, Cheers Dave

Registered 1998 SLK230K
46 Posts
Discussion Starter #44
Morning Dave, guys!
I perfectly understand (understood) the need of SDS, however none of the garages I contacted is working with such.
A local garage (鈥ou know he is a good guy, they constantly look for his services鈥︹ this kind of garage, explained by a third person) replied the SDS is actually a traction control and he can look at it:frown:
And coming from the idea even if he has the proper equipment (that can brick the car) is he going to do the right thing? I prefer not to risk it!

I didn鈥檛 drove it after reset! The driver鈥檚 side floor was with the tools I used to reach the TCM for a check and after taking the pictures of the TCM and the assembly of it I started the car to see if all cabling is done well.

Are you actually seeing the Transmission Controller Unit info / codes, if so are they just Speed Sensor??
Absolutely all I see as errors/live data is uploaded!
I have an educated guess that the Speed Sensor Codes in your picture are just CAN Communicated from another ECU to Motor ECU, it is a generic code and therefore it could be any speed sensor on the Car, likely Trans or ABS.
I know what you saying and that is why I ignore suggestions replace this and that! Especially knowing the speedometer needle is pointing to my [email protected] not the speed when moving! Still at the same moment the speedo鈥檚 being dead-like confirms lack of CAN network is it not?

If ABS, ASR / ESP is not lit up when driving then could be a Transmission Speed Sensor
Nothing but brake pad reached their limits/brake fluid level too low, actually stays ON!

Tell me about the IFs鈥..
I agree with you and that is why I uploaded the pics INFO.jpg and SAMPLE.jpg. The lack of START (at the moment) is pushing to more brainstorming than relying on PC! If the speed sensors (in the tranny as explained they are 2) are not gone they should have resistance reading as per TFT chart, part of info.jpg.

And that is why I tried the TCM reading. And I explained for the probes. The logic is, after the tranny lever is set to drive the electronic starts reading/controlling the solenoids. Oil pressure, speed sensors, oil temp, these all are being sent to TCM in the passenger鈥檚 feet. The TCM then based on the incoming data, forwards it to (that is why I asked for even block diagram) a module and/or 鈥渞eply鈥 to the conductor plate OPEN 2/3 close1/2鈥 etc. All of the above is wiring. 21 YO cables that could be 鈥 problematic. The easiest way for me is TCM 鈥 easily accessible only one cable to the tranny and therefore error free method. IF (will try again with DIY leads) there are no issues from the TCM to the TRANNY connections, move on! To the next module and again and again. Time consuming slow and annoying process. BUT it is what it is!

The NEW parts as you mentioned are transmission oil+filter that are in the trunk of the car. They are A MUST but can鈥檛 be done on the street! My search for a property with a garage (or A drive that can have the vehicle left on jack over the night) are totally unsuccessful (since beginning of Aug) so nor the IFs, nor the MAYBEs are strange for me!

Registered 2002 R170 SLK V8 5.0
2,627 Posts
Hi @BaD_81 ,

There isn't much I can really add except ..............

Have you tried ringing MB Dealer, asking them how much to do an SDS Quick Test, and give you Printed Results , (not someone else's opinion about what's wrong) !!
You might find a good guy Dealer near you, there are some ;) This is really the way forward, and avoid that "SDS idiot Garage" like the plague !!

If you do not get the correct / same resistance for the 2 Speed Sensors in Gearbox, change Conductor Plate, Connector Bushing, Trans Oil and Filter, based on educated guesswork !!
It's been a very long time since I used a Meter to check Speed Sensors, but IIRC, you will need to check between 5V Terminal and each speed Sensor's Terminal

Speedo is definitely driven from ABS Sensors, not Transmission.

If the needle is pointing straight down (ish) it is likely a separate fault, maybe Speedo itself ;)
If ABS /ESP lights are not on when driving, but do light up and go out upon Ignition on / starting, then it is unlikely an ABS Sensor fault !!

The lack of Speedo will not stop it shifting gears.

I doubt there is anything wrong with CAN Bus, those codes are in your Engine ECU, that is all your OBD App is reading, so therefore they have been transmitted over CAN from either ABS or Trans Module or both.

Great shame you're not near me, I'd have that Car fixed in a day, or at very least be waiting on the parts arriving to fix it ;)

HTH, Cheers Dave

Registered 1998 SLK230K
46 Posts
Discussion Starter #46 (Edited)
Hey guys,
@Dave2302 Thanks will keep in mind all of it for a bit later.

Sorry for the "pause"!
Since the last time I shared info/pics, I moved to a place by myself.
Lost a job, signed up for UC and finally got the log book with my names on it (correctly spelled - it took approximately 4 attempts).
And today as it was perfect weather I drained the Gearbox oil. Kinda!

Machine vs Human:
1 : 0
Attached few details!
Sucked out by a Lidl branded oil pump almost 4 liters of this:

At the back a shower curtain with plastic insert and WHITE color for comparison. On the left Red and Blue 5 liter beer keg almost full.

The oil was warm and all was good.
But following this link (very good one if the moderators dont like it, feel free to remove it) Mercedes-Benz SLK 230 Automatic Transmission Fluid Change and Flush | 1998-2004 | Pelican Parts DIY Maintenance Article
I was NOT surprised when these broke:



2 out of 6 as per the description = 100% sharp explanation and 100% step by step follow up! Good guys! :(
The locations are toward the engine and driver's side.
Looking at the bottom of the sump I am not surprised these 2 broke. Keeping in mind the surface rust and the oily look of the back part and passenger side I guess someone tried the oil draining or removing it and these 2 front bolts were problematic.
Because of the rust and dirt ( and whatever else is inside ) I couldn't drop the oil sump. It is glued like there. Used wide bolster chisel to loose it (using the gap from the front passenger side) but it did not move! Used WD40 (ebay can't always be sure what the seller run out of) as no penetration oil was available. +1 for the shopping list.
I was not prepared to drill and repair bolts today and being Sunday the closest toolstation store work till 4 pm (all of this is done outside) after collecting all the tools around the car It was 3:30 and the final score is
Machine 1 Human 0.

While the oil was draining (after sucking out the larger part) I removed the engine cover as I dropped one of the clamps when unhooked the oil pump into the engine bay and the gravity was not polite enough to pull it to the ground.

Another surprise as ... well 20 + years old vehicle right?

The fresh "wet" spots are brake or carburetor cleaner (not sure what I used, 99% brake cleaner).
But the more disturbing part is:


So as the result is not in my favor, I've prepared a list of to BUY tomorrow and will try to set it at least even! When it comes to oil of course.

The error codes were not read recently but the car started having poor idle when cold => vacuum leak "seek and destroy" will be next on the menu!

Will update ASAP!
Stay Safe Guys!

Registered 1998 SLK230K
46 Posts
Discussion Starter #48
Hey guys,
After some effort ( and pulling down ) the aluminum "nuts" were removed and the sump was dropped.
Not scary (many UTube videos) but not only iron particles were present. The magnet did not lift them all off the tray


Original filter as expected:


After removing the control assembly is visible the plug is as new!


I think I will not change a thing when it comes to the cable assembly!

The leftover of the bolts look like this:

Will try with 2 nuts, one holding the other as a stop and will try to unscrew them after nice quantity of Penetrating oil (WD40 does miracles but..) and slowly raised force with each try.
The next stem was detaching the solenoids from the conductor plate.
One was sooo stuck i used thin flat screwdriver bit to pry it UP. And as we klnow position is important.

The BIG question is: IS there away to be sure if these 2 speed sensors are GOOD?
With multi-meter on circuit I checked all the contact points and the front pins All are connected. No loose ends no broken paths.
Any suggestion for a WAY to confirm/deny problems with N2 N3 at this point?
I mean it will be stupid if install all and then have to do it again because of these 2 sensors. Plus new oil.....
Is the conductor plate safe to be cleaned with electrical contact cleaner? I just used towels paper and baby wipes to remove the oil. not sprayed, nor washed.
After spraying one Lidl 400ml Brake cleaner and old toothbrush on the valve body it still leaks brownish [email protected]
I am not sure how far I am comfortable to go in order to clean it well! The two strainers under the first 2 solenoids were CLEAN. and the mesh is not broken.

OK that is all for now! So far all good!
Prime minister was kind enough to post a letter and remind me to stay home!
Stay safe guys!


Registered 2002 R170 SLK V8 5.0
2,627 Posts

With all that swarf in it the Trans it will not work properly for very long if at all now ..............

That IS NOT Normal wear and tear ;)
Something is breaking up inside the Trans looks like one of the Ally Clutch Drums, there is a Circlip that comes out, which retains one of the Clutch Packs, causes Slipping / Ratio Errors :(

Seriously, I would not fit your new Parts and Oil to that, waste of time, if Trans does work, it won't work for long ;)

Get a good used Trans With Torque Converter and use the Parts on that whilst fitting it ;)
Don't forget to flush the Oil Cooler and lines with Solvent, e.g. kerosene and then blow clear with compressed air ;)


Registered 1998 SLK230K
46 Posts
Discussion Starter #50 (Edited)
@Dave2302 morning mate,
Not a good news!
However it explains the scratches on the gear selector...rod:

Few more down the line but it was almost midnight...
No compressor available, limited space as on the drive and the front is on ramps, the back of the car is on the ground, the slope is toward the street - facing the street.

The funny part ( not so funny but )
In oct 19 when moved the car from old to new place it actually shifted up. On a slight up the hill part of the road.
In other words I am seriously [email protected]@@@d.
That's not new.

Registered 2002 R170 SLK V8 5.0
2,627 Posts
They aren't too bad to swap out, I just don't wanna see you waste the money you have already spent on new Oil, Filter, Gasket etc etc by fitting them on an almost dead Trans ................

Ye Cannae Flog A Dead 'orse ;)

Registered 1998 SLK230K
46 Posts
Discussion Starter #52
They aren't too bad to swap out, I just don't wanna see you waste the money you have already spent on new Oil, Filter, Gasket etc etc by fitting them on an almost dead Trans ................

Ye Cannae Flog A Dead 'orse ;)
Well I can't say I am willing to spend more. Th oil, filters, etc are already paid. New expenses ( 2nd hand gear box unknown condition, promises, etc ) will be kept to minimum.
So I will risk fitting all back.
Few questions if you have been brainstorming and/or seen this movie of course!
The plastic plug s-l640.jpg had some grease on it any idea what kind of grease it is, Regular, Temperature Resistant, Silicone, Special one?
The total Gear Box Oil I got out is the metal keg of beer (beer is 5 liters but the volume should be more) filled to the top some was spilled 50-250 ml. 2 bottles 1 liter each (Lidl Orange juice) filled to the top from the torque converter and oil cooler line (radiator bottom) and 1/2 of same bottle mixture of plate's oil and cleaners. All of it goes a bit more than 7.5 liters. Could it be a factory overfilled issue that no ONE saw for 20+ years? Why I am asking, a beer keg (jery can) is made to hold more than the content it is supposed to have (every bottle you buy has extra "empty" volume) if 5,5 liters is the volume in the beer keg + 2.5 goes up to 8 liters (i have this volume purchased last September) and almost all the "sources" say 7,5. What is your experience with 7,5 and more oil drained from 722.6 Auto Box?
The hose connections from the Radiator and to the Radiator were "oily" I "opened" them with no effort whatsoever (As a Split system A/C installer I had to tight lots of pipes with 2 spanners) these were easy as breeze!
I saw no copper, aluminum or any other leak proofing "tools" in these connections, do they count on the spherical shape only?

I have extra 200000000000 questions but no experience so if you share some of yours!
And stay safe!

Registered 2002 R170 SLK V8 5.0
2,627 Posts

Silicone Grease on Rubbers.

Hoses, yes they are spherical hydraulic connectors, should never need tightening up silly hard always seal up OK unless King Kong has been there before.

You will only ever get about 5 litres out, they only need 7.5 when they are fully rebuilt and totally dry, because Converter, Valve Block, Oil Cooler and Clutch Drums all hold old oil.

Personally. IMHO (spent most of my life owning and running a specialist Auto Trans firm), you are wasting your time and parts on this Trans ;)

There are scrupulous sellers out their of good used units, (拢200 - 400), that are selling parts from a rusted MOT Fail or Crashed Car, so yeah, very likely the units are good as the car was in use prior to being taken off the Road ;)

Other than that, take it to a Trans Re-builder pay the piper and get a guaranteed rebuild job, (I'd be guessing about 拢1500 + these days), or scrap the Car ;)


Registered 1998 SLK230K
46 Posts
Discussion Starter #54
Hey All,

The updates are not exactly positive.
The result is still in machine's favour.
After draining 7.5 +/- 0.2 of G-Box oil (torque converter, oil cooler, sump ) I filled exactly 7.25. The procedure was like:
First 5 L were like tap water in the sink fast and traceless. The 6th bottle was hesitating but the 7th was about to overflow the funnel and CREATE some extra mess.
So 7.25 was the limit the car was off the ground and leveled. Front on platforms, rear on supports. Started up the engine and slowly changed gears - 5 seconds each position. When reached to 1 Started back and each position was hold on for 20_30 seconds.
Got under the car no oil. Joints - no oil.
All good ( I mentioned it was levelled right? ) kept the engine running until 80掳C were measured by the cluster. And my improvised tool ( 6 mm clear hose with markings for 25 and 80 degrees ) show the perfect score - golden middle.
Good news right. So I took it off the stands and on it's "feet" I moved it back and forth few times to be sure it is all lubricated.
And move it off the secondary drive to the front of the house entrance.
For the night ( the front is with a serious slope and cleaner - no grass cleaner small pavement bricks ) as leak Will be easier to spot.
Next morning Nope no leak, and as it was the engine oil's turn ( - 570 or so on the odometer ).
And back to the secondary drive/service spot, reversing in ( again slope, but less scary) in the half way - slowly as I am not used to the dimensions of the car, nor parking it in reverse, on the half way in I stoped. Looked around and when sure all clear ( sides, back ) I released the brake and it did not move, stepped a bit on the gas 1200 rpms +/- 200 the car slowly moved back. Switched to D went on the street 3-6 meters forward, then R and started with no worries whatsoever 800-900 rpm up the slight slope car was moving easily.
When I got out, a trail of UGLY smell Red fluid was leading from the entrance of the secondary drive to the back of it - 4 meters.
Did I fill my pants? 馃樀
Raised it and removed the tray under the engine because of the cooler joints - dry and clean.
And then I saw the trail from over the Torque converter going under the driver's seat side and front right corner of the G-Box oil sump. The cable was not hooked to its please and no oil was on it.
Up till that moment I had no idea the G-Box has breather. Cleaned up the oil and proceeded with the engine oil. As the front was lowered than the back I did not check the G-Box oil level.

The engine oil change was another episode of the troubles in paradise and will get to its later/tomorrow or...

Stay safe guys!

Registered 1998 SLK230K
46 Posts
Discussion Starter #55 (Edited)
After many moons and thousands of ... articles, wiring diagrams, headbangingS... the GORDIAN KNOT is about to be nailed!
First a lesson about the Errors: 1747.png
Why the f********k I was not looking closely? My cheap OBD explained many others but CAN BUS was among them!
Another one called 0500 goes with many headbanging but this guy nailed it: SOLVED: Five Idiot lights, P0500 P0600 P0720 and...
Now it is about to become long and (Gordian Knot) ugly!
Front right speed/abs sensor shows open circuit after getting the left wheel off and measuring more than 1Kohm plus the beeping test with hand spin of the wheel. Yes there was rust and there was dirt - no other way!
Original Ah? 22 years old ah? Well part of life!
Cleaned the small openings but...nothing changed! I know they are nor exactly clean, but the right hole on the pic was actually full and leveled with the plastic surface. WD40 plus gentle rubbing upside down on a piece of rug couldn't resurrect the fallen one!
SO I was thinking to measure the cables themselves (vibrations, metal surface, years - short) but couldn't find the combination of r170 98 ASR module location in the face lift the light of the cluster is combined!
Mine is:
Now the ugly part my trunk had extras one of them is this:
The whole ABS pump. And it was with nice traces of EGGhead approach for opening!
The small "holding" washers (google translator was not able to help with the technical translate) were still on top of the metal pins. But one corner was actually broken! I took pictures after i opened it as visible on the pic above!
It's been soooooo UGLY attempt that:
The PCB is actually.... well you see the picture!
Not straight, not sure if broken but I can't see cracks! Probably because of the sealing they made back in '98. It was as new. And when talking about NEW look at the 2 "stamps" on top of the motor housing:
No problems to read the chip model they used ah?
Still after cleaning - peeling off the clear film i saw:
Not exactly good looking pins. Right side is the 15 pin connector. Heat, high current, vibrations...cracks!
The groups of 4 legs forming rhombus (in my opinion) are the soldered coils of the solenoids! And zoomed they were brownish plus a bit of cracked/one side or under the elbow of the coil ending.
A note this is the module that was in the trunk I guess the old one!
And as I guess, the Gordian knot looks like that:
Front Right ABS/speed sensor died or was killed by the board above!
The can bus was not able to provide signal to N (whatever number) module in the black box located next to the battery in the engine bay. And from there, reading the article I posted above a cascade action of the sh*****t whirlpool had my hands, mind, eyes going through process of... everything else but a sensor ABS/Speed whatever you going to name it.
I need more pictures.....

Registered 1998 SLK230K
46 Posts
Discussion Starter #56 (Edited)
Why I need more pics?
Well the ABS and the ASR are NEW for the trouble in Paradise in general.
Before was like that: Dash.png
Nothing less, nothing more! The MOT said low level of brake fluid. The actual reason is different.
And NOW: Light.png
Here I must say, nope I HAVE TO SHOUT:
Guys, when light is LIT, before anything else open that K40 relay board!
IMG_20200512_141425.jpg IMG_20200512_141434.jpg
Nope it was not opened before no Burnt connectors, no fireworks. Just ... virgin 22YO underestimated K40 Board!


Now the missing P0170, the file name is the actual date screenshot/picture was taken:
SEP 2019
Sep 2019 after clearing the errors
May 20 P0341 is new and "pending"
Just because when I took out the MAF for cleaning, cleaned the throttle valve, replaced the air filter and Spark Plugs, took off cleaned and re-installed the magnetic CAM adjuster I forgot to hook it up.
The poor idle however is still present :(


On their way I have front ABS (not the cheapest I could buy, but not ATE) sensor and a set of front brake pads (not the cheaper again, but not ATE). Because of the "original" 2 warning lights on the cluster from the beginning of the trouble in Paradise article.
I have tons of pics in the process, but the limitation of 10 per post ....

Will update regarding the rest of the ERRORS when replace the brake pads and fit the ABS sensor,
Stay Safe Guys!

Registered 1998 SLK230K
46 Posts
Discussion Starter #57
Well as we all know,
The world is crazy now!
I ordered 2 things, set of front pads plus ABS sensor last Saturday.
Got the brake pads Tuesday and installed them.
IMG_20200519_150250.jpg IMG_20200519_150256.jpg I could have the edge left by the old ones IMG_20200519_164719.jpg IMG_20200519_164637.jpg filed, but thanks to ECP I am missing the key tool to do so. And as visible the edge is too deep to be sand-papered!
I requested tracking number to see where the sensor is and the answer was it will only tell us when it is delivered!
Seriously when I get it I will know, but... and request from the seller to be PATIENT...
This is my favourite lately!
We got your money, we got your order and we asked you to stay calm and wait, how difficult it could be!
So I got 50% of what I ordered and 1 week gone when the delivery was noted 2-4working days!

As far as I know, it is common thing but it doesn't change the facts!

Stay safe guys!
Will add pics later!
Use your computer to upload/edit, the smartphone has his own idea of what you are explaining!馃檭
41 - 57 of 57 Posts