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722.9 Transmission Service – “Service Required. Do not shift gears. Visit dealer”
Just finished doing the trans service on my 2012 E350 Bluetec at 70K (car is “new to me.”) Upon starting the car to begin warming up the fluid I got the following message: “Service Required. Do not shift gears. Visit dealer."
My Autel translates this as “CAN bus off fault code 103C00.” The code will not clear. My first thought is that I loosened an electrical fitting when removing the pan, but nothing seems loose. Does anyone have any advice on what may have gone wrong here?
I'm going to guess that there's a connector problem.
The error is telling you that the CANBUS (CAN) controller in the ECU has shut off or isolated an area BUS node due to out of range reporting from that node (module).
The out of range reporting can be data received that's beyond programmed limits or it seems in this case the transmission node/module is not reporting data to the ECU. If it were a solenoid you would get a code for that individual solenoid circuit but the ECU is telling you it doesn't know what the transmission is doing, thus the service message.
Bear in mind you can get a host of error codes that can sometimes lead to chasing rabbit trails when there's only one problem. That's because the ECU needs data from many modules to run the engine. Modules that aren't able to talk to other modules can also throw a code.
Since you were in the transmission (did you replace filter?) you may have jostled a connector that could have been marginal to begin with, like maybe a loose pin. You might have loosened something on the conductor plate or there's wiring broken between the transmission and the ECU.
Mud thanks -- yes I did replace the filter. I have been going over the electrical connections on the outside -- but are you suggesting that the loose connex might be *inside* the trans pan? Thx...
Yes, good question. I took out 5 liters and put back 5.5 liters per instructions.
You took out 5 liters but filled back in 5.5 liters. Did you then let the car run and allow transmission fluid to come out via the over flow tube as the fluid was heated up to the temperature (80 C) if I remember correctly?
if you did not allow for the heat expansion fluid removal you have increased the fluid level inside the gear box. This higher fluid level may flood some electrics that it is not supposed to flood inside the box?
You took out 5 liters but filled back in 5.5 liters. Did you then let the car run and allow transmission fluid to come out via the over flow tube as the fluid was heated up to the temperature (80 C) if I remember correctly??
I have not done the heating to 45 C/draining of excess fluid yet because the transmission is not engaging.
Mud thanks -- yes I did replace the filter. I have been going over the electrical connections on the outside -- but are you suggesting that the loose connex might be *inside* the trans pan? Thx...
It's possible but I can't tell you for sure - I can't look at or know exactly what you had done.
Also check to see if the TCM (transmission control module) is on a fuse, sometimes a very basic item. You'd need fuse box or SAM layouts to verify.
There's a way to verify CANBUS communication between TCM and ECU but you would need vehicle wiring diagram to verify connector pin locations and what circuits or CANBUS they are on. You'd also need additional stuff that I don't think you have but here's the way just for info.
Connector can be backprobed for CANBUS send and return. A scope is used to look at CANBUS waveforms. Normal waveforms to TCM can be compared with waveforms from TCM. Obviously no signal back means the problem is inside the transmission. You can backprobe all pins to verify signal and voltage but again, you need wiring diagrams and some equipment. A multimeter can be used for voltage verification - remember that TCM may be fine but if it's not supplied with power and ground it's not going to communicate. That's why I mentioned checking basic fuse and connector stuff.
You can get WIS/EPC discs on eBay for cheap - they give you factory data on the car including diagrams. But be sure your pc can deal with 64bit operating. I also use Mitchell DIY on our other vehicles, about $48 for 4 years of access. Don't have it on the MB but it's been great on our other vehicles. I'll probably get it for this car, just haven't needed it yet.
This message is due to a mechanical problem in the ISM or no communication with the ISM. Do you have a scanner that can establish communication with the Engine, Transmission and ISM??
10-04-2020, 11:33 AM
