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Discussion Starter #21
I am not familiar with the Autel unit, but there should be a way to tell it to scan the TCU. Some of those codes you posted do appear to be TCU related:


This may be a bad shifter unit based on some of those codes. You should definitely align the shifter linkage rod. And while you're under there, check the 13-pin electrical connector on the transmission for any signs of oil leakage. Disconnect it and check for oil inside the connections as well as for oil in the wiring harness itself. Finally, check the TCU for oil intrusion. It's located in the passenger footwell, Fold the carpet down from under the dash, remove the sound insulation panel, and there is a metal "cage" that contains the TCU. It has three plastic nuts holding the cage to the body.
The way the unit works is you can select OBD2 or Scan and the scan will grab the vin and then walk you through a couple of steps like the year range of the vehicle and left or right steering wheel. Then it scans both the transmission and the engine. The first set of codes were listed under STORED in the transmission section. All of them were actually stored. After it scanned the transmission it actually said no faults but once I clicked into it I saw all the stored codes.

I've already looked at the TCU before when I was searching for the ECU when I started having all these issues and from what I remember it looked brand new behind the carpet. No water damage or anything looked great I'll check it again just to reassure myself on that. I'll pull it up on my car ramps in a little while and check the 13-pin connector to see if it's okay also. I don't really have anyone to help me adjust the linkage so that's one reason why I haven't. If you unbolt the shifter it moves about 1 full inch so I just kept adjusting it and shifting through all the gears till it felt the best and I stuck with that. Since then I've only had those couple of issues. I don't really feel its necessary to adjust it on the rod when the whole shifter moves it should be easier to just adjust it with the entire shifter. Which is what I did just from feel.

One thing I have noticed is since I've adjusted this shifter I no longer have the issue where sometimes randomly I'll be driving the car down the interstate and I lose the speedometer and my cruse turns off and the transmission locks into gear as it goes into limp mode or something. Sometimes it would lock in high gear till I slow down and it downshifts then it would lock into 1st gear and not shift anymore. Sometimes it would lock into high gear and when I would take off from a dead stop it would bog down really bad and take off really slow till it catches up to speed. This hasn't happened again since I adjusted the shifter I took the car on a 2.5-hour trip yesterday and drove great then drove it back the same night and it drove great no issues at all for this entire trip. So whatever was causing that somehow got fixed with the adjustment so I wanted to mention that too.
 

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2003, W203 (C240)
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Yet another alternative is to find a matched set of ECU, EIS (ignition key receptacle), car keys, and shifter module. That's the "magic 4" for Theft-Relevant Parts for cars like yours that (fortunately!) have a 5-speed transmission. Swapping out all four will keep the "matched set" and thus keep the immobilizer happy.
I also thought about this. You mean "matched set": the 4 (or maybe all of the) control modules from one car must be exactly the same, as from the other ? I mean both cars must have the same engine, same transmission, in case one is 4matic, then the other too, same year of production, and the model number.

Or is it more reliable to check, if the VIN numbers are the same ?
 

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Discussion Starter #23
So I pulled the plug out you were talking about and it has a slight bit of oil on the side of it. I pulled the harness as much as I could and blew it out really hard by mouth since I don’t have an air compressor and then wiped it again it didn’t seem i have much on the inside. What I may do is take it back off soon and spray it down really good with carb cleaner and then blow it with a compressed air can to be sure it’s super clean. I didn’t see any oil leaks above this plus it’s all pretty dry so it’s definitely not coming from above.

2607877
 

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You need to replace the seals for that connector to stop the oil leak. Search "pilot bushing" for lots of info on that. You also need to check the TCU for oil intrusion. You may not see oil on the wires, but it can still "wick" into the TCU.
 

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Discussion Starter #26 (Edited)
You need to replace the seals for that connector to stop the oil leak. Search "pilot bushing" for lots of info on that. You also need to check the TCU for oil intrusion. You may not see oil on the wires, but it can still "wick" into the TCU.
I ordered the seal connector for the transmission should have it at the beginning of next week. The TCU behind the carpet on the passenger side looks perfect connections look brand new. No oil or water damage. Wires coming from the firewall all great also.

I also erased all the codes the other day since the car was working great just to see if any of them would come back and after 2-3 days of driving it every day I've yet to see any of the problems at all. The only codes correctly showing are

P2001 (P0400)
P203A-8 (P1999) - From what I've read this code can be ignored because these Mercedes throw these codes sometimes and it's not reliable
P20CC-8 (P1999) - This one here something to do with 'Rough road detection' so probably another that can be ignored

So the only code that is important it seems is the EGR valve being dirty. I'll buy some big wrenches soon so I can pull it out and clean it. I don't have a 22 or 24mm wrench so that's the main reason I haven't tried to clean it. Sadly that will cost me $20 for two wrenches or I'll have to buy a whole set for $30 that contains both of them. I was hoping that one of the local part stores would rent me some but apparently they don't rent wrenches.
 

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Discussion Starter #27
You need to replace the seals for that connector to stop the oil leak. Search "pilot bushing" for lots of info on that. You also need to check the TCU for oil intrusion. You may not see oil on the wires, but it can still "wick" into TCU.
So it broke down again this morning. Drove great for several days while the weather was nice and cool and dry air. Took it across town earlier and stopped at a store got some food then drove out to the park went to get in it and won’t start again. Moved the shifter back and forth like I did last time to get it started and still nothing it won’t show any highlighted gear on the dashboard.

2608154


I’m going to go ahead and match a part number on this shifter to a used one on eBay it has to be the shifter I’m just confused why it doesn’t throw codes. I scanned it while it won’t stop and shows no faults or stored codes for the transmission.
 

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Discussion Starter #28 (Edited)
I bought a shifter from a local salvage yard today no go. It's not the shifter. Tomorrow I'll change the Pilot Bushing after I have the damn car towed back here to the house. I guess it's always possible that I got a bad shifter from the salvage yard. I need to research how to test the module and see if it's bad or not.

It still shows no selected gear just like the image above. I'll do more researching this is so aggravating. Drove perfect for 4 days then bam right back to breaking down again. This is the most frustrating thing I've ever experienced as soon as I fix this car it's getting sold immediately after.
 

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I also thought about this. You mean "matched set": the 4 (or maybe all of the) control modules from one car must be exactly the same, as from the other ? I mean both cars must have the same engine, same transmission, in case one is 4matic, then the other too, same year of production, and the model number.

Or is it more reliable to check, if the VIN numbers are the same ?
Did someone alredy realized to swap the control electronics from one car to another ?

An other question: is it possible to swap the transmission or the engine from a (W203, C240, 4matic, year of prod.=2003) to a same model WITHOUT 4matic ?
It would be nice to know these, because i had an acident with my car. The subframe is bent at the front, but the engine and the transmission seems to be ok.
It could be an alternative for me, if i could swap these parts to another model.
 

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@RollinCajun: I believe that initially, the gear indicator comes from the TCU, but I believe that if the gearshift and TCU do not agree (such as with a bad linkage rod or shifter) then it also shows blank.. Since you have oil in the 13-pin connector, you should take care of that first.

@99d29: You should start a new thread for your question.
 

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Discussion Starter #31 (Edited)
@RollinCajun: I believe that initially, the gear indicator comes from the TCU, but I believe that if the gearshift and TCU do not agree (such as with a bad linkage rod or shifter) then it also shows blank.. Since you have oil in the 13-pin connector, you should take care of that first.

@99d29: You should start a new thread for your question.
Yup I did that yesterday but for some reason, I tried about 20 times to install the new pilot bushing and no matter how I turned the plug to put it inside that pilot bushing it wouldn't go all the way in. I had to take the new seals off the new unit and put them on the old unit because the new one, even though it looked exactly like the other, wouldn't work for some reason. I even glanced inside of the pilot bushing to make sure it looked the same as the old one and I swear it looked identical but it just wouldn't take the plug. Before I installed the old one back with the new o rings I went ahead and pushed a rag inside the hole about ten times to get as much of the oil out as possible but even after ten times or so pushing the rag it was still getting oil on the rag. I assumed this was normal so I stopped doing it and went ahead and installed it.

So update with the no start problem. I installed the new shifter (used from a salvage yard) and I couldn't get it started. I kept trying and moving the shifter around and finally, it started but got stuck in first gear so I drove it into a parking lot and left it overnight. I went back the next morning and still wouldn't start so I unbolted the shifter again I slid it forward and back a few times and nothing. Then I waited a couple of minutes and done it again and this time it started so I bolted it down and two days and it hasn't had any issues at all.

I pulled it on some ramps yesterday and I checked the rod adjustment put it in drive and checked the shifter on the transmission and it was all the way forward so it was actually set perfect how it was so I left it alone.

I ran a scan on it earlier and I got p2315 on the transmission but nothing else showing up. For some reason, I have an SRS on my dash and no idea why I tried to scan the ABS and this stupid maxi elite tells me that it won't do it for my model it's not supported. Little pissed off about that when they advertised it as working for almost all vehicles so I can erase the code and see if it comes back. It didn't show up till I changed out the cluster. I got another one from a salvage because my LCD is almost shot I can't see anything unless it's cool or cold outside. Instead of just changing the LCD I swapped the whole thing and it gave me errors I guess because it couldn't read the mileage so I pulled it back out and installed the LCD in mine and replaced it and everything works now but it shows SRS. I'm assuming it's just an error because I swapped the cluster.

After researching the p2315 from the PDF you gave me that was thrown when I swapped out the instrument cluster but I'm not sure about the SRS on the dash.

I'll give more updates when it breaks again or if it doesn't after a week I'll still give an update. I checked the TCU again yesterday and the wires are clean and unplugged both of the wide connections on the bottom and it's all clean no oil or water or anything. It looks brand new. Here are some pics to show what I see.


2608325

2608326

2608327

2608328

2608329
 

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Discussion Starter #32
So whatever is causing this car not to start has reached its end I guess. Two days and the car won't start. I've never had it go this long without starting so I decided just for the hell of it to take apart the TCU and look inside and it's perfect. There has never been any transmission fluid inside this unit.

I'm at a point where I don't know what to do next. I pulled the pilot bushing back out to check it and it has a very slight film of oil on it so I wiped it off and put it back. I don't know what else to try.

2608891

2608892
 

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Discussion Starter #33 (Edited)
When I switched relays K (AT relay) and S (Starter relay) car tried to start but it sounded like the battery was low and it didn't have enough. So I tried to jump the car off with my sister's car using jumper cables and although it's showing P as the indicated gear now finally that part works it still won't start. I turn the key and nothing. So I'm sort of getting somewhere. I'll put a battery charger or a jumper on it later and see if I can get it to crank over.

I ordered two brand new ones from amazon will have them in a couple of days. I don't know which one is the original and which isn't since I swapped them around a few times trying to get the car to start so just to be safe I got two new ones. No idea if the relays are even bad but since I'm not sure I ordered two new ones regardless.
 

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"Turn the key an nothing" is probably a dead battery from all the starting attempts. Even with a jump, these cars can refuse to crank if the battery is very low. You can try removing the negative lead from your car's battery and then jump with another car to see if that works.
 

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Discussion Starter #35
"Turn the key an nothing" is probably a dead battery from all the starting attempts. Even with a jump, these cars can refuse to crank if the battery is very low. You can try removing the negative lead from your car's battery and then jump with another car to see if that works.
Yeah, that's what I figured but the thing is anytime it won't start it never turns over. I put in the key and turn and I get nothing but the issue has always been the gear indicator not showing a selected gear but the relay swapping fixed that somehow. I must have some type of slow drain on the battery. I had one months ago that kind of fixed itself. If I left the car sitting for several days it would need to be charged then one day it stopped doing that. I let it go for about a week once and it was fine started right up but it seems the problem that was draining the battery before it doing it again so that's another issue for later I guess.
 

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Discussion Starter #36 (Edited)
Okay, so I charged the battery to full and still nothing. The gear indicator is saying P now since I swapped the relays around a couple of times. So the transmission is not the cause for it not starting this time it's something else. So I need to work out what could be causing it now. I have a feeling it's that starter relay. I'll have two new relays in Sunday so we will go from there I guess.

I forgot to mention that when I swapped the relays around I never thought about disconnecting the battery so it was connected while I was doing that. I did check all the fuses again to make sure I didn't pop a fuse doing that and from what I can see the fuses are all good still. I feel like it has something to do with those relays.
 

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Discussion Starter #37
It's definitely not the relay. I haven't gotten the new ones in yet but I swapped another one from the back sam and still nothing. I decided to pull the starter relay and turn the key on and try to jump the relay to see if the car would turn over and I see some small sparking going on when I touch 30 and 87 together but I get nothing. Does that mean my freaking starter went out all in a sudden? I mean it hasn't even sounded like it was going out it has always started the car with no issues. I'm so confused on that and it's it ridiculous how hidden this starter is on this car I can't even see it no matter what angle I try to look under or from the engine bay of the car. From what I see in the manual you have to pull the whole exhaust out to even get to this starter that's ridiculous. I wanted to hit on the starter a little with a hammer or just a piece of pipe and see if I can get it to engage just for the hell of it but I can't even do that because there is no way to hit it with all the heat shields, exhaust, etc in the way.
 

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Discussion Starter #38 (Edited)
So all these problems I've been having and it seems my starter is bad out of the blue as if all this other stuff wasn't enough already. I ran a jumper wire on the starter relay to see if I could get the starter to engage and nothing. So then I pulled #52 fuse and ran a wire from the battery to that to see if I could get it to engage the starter from there and it sparks a little and nothing.

Does this for sure mean that my starter is no good? I've looked all over the internet for a guide to replace this starter on youtube and I've yet to find one.

Looking at the WIS I bought it looks to be under the freaking exhaust manifold on the passenger side and there are heat shields galore surrounding it so I can't even see it no matter what angle I try to look under the car. From what I've read through the WIS repair section you have to remove the whole exhaust from the cats to the back where they connect in order to even access the heat shield that the starter is behind. Can anyone confirm this is how I get to the starter?

As stupid as it sounds I wish this was one of the cars where the starter was under the intake manifold because at least then any DIY mechanic can replace that. This one is something else. It's ridiculous that you need to jack this entire car up in order to have enough room to drop the exhaust out of the way to get to this starter. They should have just left the thing in the intake like some of the other Mercedes.

I don't even have a lift to do this job. I don't have the money to pay someone else either this is a hell of a job. Without the car even starting having to tow it to a shop and have them change it is going to end up like $1000 or some crap. On top of all that I still have the issue where the car won't start sometimes where the gear indicator isn't showing it's in park. I fixed it for now by moving around some relays but that doesn't mean it won't come back so that's still an issue I have to work out after I get the stupid thing started again.
 

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First of all, to test a starter, you check voltage on it. The large cable is direct-wired to the battery, so it and ground should give you 12v. Next, you need to check voltage at the solenoid when turning the ignition switch to start. If you get voltage there, but the starter does not operate, you have a bad starter (or bad solenoid or a corroded wire leading from the solenoid top the starter motor).

If the all of that checks out, you go "upstream" and check the relay ("S" on the fuse panel) and the fuses (52 and 53). If those are good, then it's an electronics issue.

If you do have a bad starter, it's not that bad of a job, but you will have to lift the car, remove the lower engine covers, and, the only really bad part, is detach the exhaust. WIS states to remove the entire exhaust system, but should be able to just detach the pipe from the manifold and also detach the exhaust support brackets at the transmission so that it will drop down enough for the starter to clear.
 

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Not saying using the codes isn't a good place to start but I would check underneath the floor mats for signs of water intrusion. There are connectors for the CAN bus that are very easily damaged by moisture. If you find water damage then you probably have a bad Front SAM. It gets wet before the water gets into the interior. The drain holes that drain the area where the Engine computer and SAM are located are very easy to clog. When a good rain comes the computer gets wet and this can cause much erratic behavior.

My car would just die on the road and not start. It gave about 20 different codes. Basically everything on the Front SAM was not communicating When it was acting up. I would tow it home and the next day it would start right up. I bought a used ECU of ebay and had a company in Texas copy my old ECU configuration to the new ECU. Once I got it running I removed the wheel well liner to get to the drains and cleaned them out then cut them a little so they won't clog as easy. When you see them you will understand why then need to be cut.
 
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