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Bought this car with know that poss it had a bad trans. But, I didn't know what it took to do a full used AT swap.
The TCM has to be married/coded to the car -
I have learned so much about MB it's scary.
So the only code I am getting 0605 Y3/8n4 VGS Defective. It only appears when my ATF is over 80 Degrees. I have tried every solution - chased power all the way to the AT connector. Pulling codes with iCorsoft.
Pulled the TCM, nothing broken along the way.
I found a place on eBay who says they will diagnose it. If fixable, they'll fix it. But, it possibly can be irrapairable. From what I can tell the flex/ribbon has a crack between the AT connector and eve TCM itself.
My other concern is it that it has 145k miles. The ATF has clearly never been changed. The most microscopic chrome flakes at the bottom of the pan/non in filter. But, a lot of grey soot. All of it seems very smooth including the stuff in the filter that I cut open.
It drove very strong every time it went driving until it threw the code & went into limp mode.
Like I said, anything to add - feel free
I'll post how this goes along. This is intimidating, no joke - and I work on cars on a daily basis. Def a learning curve to say the least.
Last edited by C300Matic; May 7, 2017 at 12:32 AM.
All you have to do is replace the defective y3\8n4 and enjoy life!!
This is not as simple as it sounds - unless??? - I'm all ears
Best option I have found is a refurb, programmed to my VIN TCM off eBay coming out of China for 335 shipped.
I opted out of just the repair since there is a possibility of the TCM being terminal. And, I get a piece of mind that now I am using a completely different TCM < which means it really has no reason to come back with the same fault code.
Edit:
Ahh, I just noticed that you do MB coding. I have contacted everyone who is MB anyone in AZ & found no one who could do it on the spot - the unit would still have to b shipped out of state. This way, I get a whole new unit which will be already coded for the car.
Last edited by C300Matic; May 8, 2017 at 10:07 AM.
I used that eBay option you mentioned but I diagnosed the problem, ecu works perfect. Plus I didn't have to worry about a coding issue. I'd recommend doing that that, I don't trust Chinese electronics plain and simple...
I used that eBay option you mentioned but I diagnosed the problem, ecu works perfect. Plus I didn't have to worry about a coding issue. I'd recommend doing that that, I don't trust Chinese electronics plain and simple...
What was the problem and which listing?
I think a fresh unit is a better option me. The code that my TCM is showing doesn't seem to be too common. And from what the guy in LA said, it's possible that it is terminal & they will not be able to repair it.
I think a fresh unit is a better option me. The code that my TCM is showing doesn't seem to be too common. And from what the guy in LA said, it's possible that it is terminal & they will not be able to repair it.
Then their the wrong people to use, don't remember who exactly I used. My ecu had a bad ground switch solenoid in it that caused a misfire. Diagnosed it and sent it to them telling them what it was, even told them what terminal it was, I know... I'm such a nice guy ... you should be able to call them and ask.
actually, thinking about it not sure if it's the TCU. you sure there isn't a sensor in the circuit for measuring fluid temperature? I'd check a diagram and make sure, unless the sensor is internal to the TCU.
Weistec had a valve-body rebuild plus a TCU update that could be done to the 722.9 transmission. Here's what I received from them, however the link is currently 404:
William,
I apologize for the late reply. I wanted to get a solid answer for you on this. The transmission in your C300 is a 7G, however it is torque converter based, and not MCT. We do have a valve body upgrade that is available for the AMG 7G (nearly the same transmission) and we also adjust parameters in the TCU to help with performance. I have asked our engineers, and they said this modification can be done to the C300-C350 valve body as well. The cost is the same as our AMG valve body. Please view the link below. Thank you and let me know how I can assist from here.
Just because a fluid looks dirty or has changed color doesn't mean it has broken down. Short of getting it analyzed your comment may or may not be true. Just saying.
It still feels like it has similar consistency & lubricity - but, the color dif is like night & day
Think of our cars' synthetic oil. Looks Hella brown and smells somewhat burnt but as per our oil analysis shows... They're fine. I guess that's the case with our tyranny fluid but I haven't seen an analysis from anyone.
Here it is, the TCM i ordered from Japan already installed on the valve body. Straight perfect, couldn't have gone any smoother. Cleared all the TCM codes, and fired right up. No limp mode at all - shifts strong. Only thing I notice a tad is how it likes to stay in higher gear when letting off the gas or light braking. Nothing bad at all & seems to be better as its working through the drive cycles.
Did this fix your issue? I replaced my conductor plate and the car worked for three days and it does not shift properly anymore and I am getting the P0705 again!!!
Could it be the TCM?
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
... you should be able to call them and ask.
