270cdi can-bus problem on gearbox.
Does anyone know of typical problems concerning a can-bus problem related to the gearbox on a 06 270cdi? Really appreciate any help with this :)
Sorry to hear that you are still having trouble with this car.
These gearboxes have a known problem with the electrical wiring, whereby pressurised transmission oil flows though the cable sheath of the electrical cable that connects the valve pack to the control unit and ends up damaging the control unit.
If you have checked the above and have determined that you have a CANbus problem, have you been able to check the actual CANbus wiring? It's a twisted, 2-wire system with some sections using earth screening. It should be possible to check the CAN-bus wiring from end-to-end. The modules at the start and end of the bus should have termination resistors, for the bus to function, so check that all modules on the powertrain CANbus are properly connected.
In the old days there was just a vacuum line from engine to auto gearbox. There's something to be said for old technology.
here is a link to the connector leak fault, which is typical:
https://www.youtube.com/watch?v=QvwxeCy8xRQ
If the above is not your problem, you need to find a wiring diagram from the Workshop Instruction Sheets and check the CANbus wiring from end to end.
The ends of the CANbus line need to be terminated with an appropriate resistor for the line impedance, to prevent reflection of signals. These terminating resistors are normally built into the modules. first check the wiring to ensure that you have no broken wires.
some info here:
http://forums.mercedesclub.org.uk/showthread.php?t=129838
http://www.aa1car.com/library/can_systems.htm
http://www.aa1car.com/library/can_systems.htm
Note that a CANbus fault related to the transfer-case is quite common on the G and is just spurious and doesn't mean anything (I have those regularly on my G400). The electric control of the transfer case was a bad design, but it's not related to the gearbox. If you can communicate with the gearbox control unit through diagnostics, then the CANbus is working. if your issue is the gearbox going into 'limp-mode' then check the switches on the gear-selector lever, try to use Manual gear selection and see whether the gears are displayed correctly in the instrument binnacle. Sometimes the switches on the gear-selector fail and then the gearbox enters 'limp mode' breause it does not know what gear has been selected. This was a fairly common occurrence on some BMWs with the same ZF gearbox.
Also, are you sure that this is a gearbox issue and not an engine issue. check the condition of your air mass flow sensor and also the EGR. These are apparently other common cause on the 270 CDi.
If you move the gear-selector lever to D and then tip it left and right it will shift up and down manually. The actual gear should be displayed in the dash, instead of D it will show 1,2,3,4 or 5. The switch mechanism is either in the lever assembly or in the gearbox. If the gear display works correctly, then this will not be the problem
The H & L issue on the transfer case is a common problem. The display sometime shows a blank when the system does not know if the transfer case is in H, L or N. It's a problem with the electric shifter and its sensor. Keeping the H-L button pressed will force the system in to either H or L and reset the display. It is not related to your gearbox trouble.
I was trying to understand whether your 'limp-mode' fault is related to the gearbox or the engine. What is the actual warning display on the dash, when the problem occurs?
If you can diagnose the gearbox with a STAR tester on the OBD/diagnostics port, then your CANbus will be all right. The problem will not be that. Have you managed to read any fault codes from the grearbox?
Sorry to hear that your troubles persist.
Please could you clarify who is doing this work for you?
I think that if you continue to change parts at random, it will end up being a costly exercise. CAN bus errors may not be relevant. The gearboxes are complex and contain may sensors, any one of which could give issues.Are you able to run diagnostics on the gearbox, can you see that the shaft-speed sensors are working?... and that the gear selector lever position is being registered correctly? if you wish to check the CAN bus, you will need a wiring diagram. Then, disconnect all the power-train control-unit connectors (engine ECU, gearbox, transfer-case, braking system etc and check the CAN bus continuity from end to end, at all the connectors. It's a 2-wire system. The fault can actually reside with any module on the power-train bus, as well as with the wiring itself, if there is an interruption to the bus, or one of the modules is corrupting the communications. The gearbox communicates with the engine and braking system and it may go into limp-mode if it does not receive the correct communications. What diagnostic codes do you have so far, if any?
As you have had some intermittent success after changing the gearbox selector lever switches, start by carefully checking the wiring on these. I don't know the particular case with this model of gearbox, but in many cases, the selector-lever switch data is transmitted on CAN-bus.
If the vehicle has a full MB service history (I don't know if it has?), then you may find MB willing to take the case on, as good-will, to get to the bottom if this problem.
Sorry to hear about all your troubles, it must be very frustrating.
I would like to buy one of the latest diesel G Wagons with a view to keeping it for the next twenty years like my last one.However with modern electrics creating the type of problems you have I don't know if that is possible anymore.
I know this is nothing perhaps to do with the issue
Had a 27crd jeep cherokee with the merc engine and gearbox control.
Kept going into limp mode and gearbox would not work properly. Plugged it in but no faults only a fault code that could be many things
What sorted it was a camshaft position sensor on the front of the engine. I thought i would try it as i have had a similar issue on mercedes ml 270s
I thought i would try a cheap pattern part and it worked fine since. I did try the old one again and it was ok for about 20 miles and it did the same again. Re fitted the 17 pounds cheapo one and all was fine for 2 years on. Then i scrapped it and put the engine to good use. Really comfy car but the rest has a lot to be desired lol
Might be worth a try for a small cost, easy to do as well
I only mention this as it did not come up as a fault on any car specifically as the cam sensor. Just old skool intuition as gearbox is sensed from cam on 270 engines not the crank i believe
G
You will kick yourself if its something simple. I cant believe you are having all these issues
Very sad to hear and i bet you are thinking toyota landcruiser. Thats a sound choice but stay away from land rover if you think you have issues now
Most i know are in dealers more than on the road. Sad but true and i see it daily
Typically, the accelerator position sensor, cam-shaft sensor and crank-shaft sensors can fail, but I believe you had already changed the accelerator position sensor.
Check also the throttle-position sensor, if it has one, as this is often used by the gearbox control unit to check plausibility and it may cause the gearbox to go in to safe-mode. (I had this problem on a BMW with the same 5-speed ZF 5HP-xxx box). The throttle position sensor helps the gearbox decide when to change gears. In most Cdi engines, the accelerator pedal is electronically linked (accelerator position sensor) to the throttle, which uses a drive motor and position-sensor to actuate.
It does sound like it may be a simple problem, which has managed to elude your technicians.
I can do this with very basic 'car-soft' diagnostics, so I am sure it can also be done with the official STAR diagnostic system: It should be possible to monitor the gearbox in real-time and see the readings from all the sensors, as well as the shaft speed and turbine (torque converter) speed. Also, the internal valve status and gear-selector position can be checked. If you can see all these parameters, the CANbus must be working fine. On my BMW, I could see that the throttle position would intermittently read 100%, when the accelerator position was at rest and this would cause the gearbox to enter the safe, limp-home mode. It was a worn potentiometer.
Hi
A lot of other garages would be not so willing to help as people have changed a lot and dont know where to start
I would have a good chat to your mercedes dealer and explain all. You will know if they are willing to help within 3 minutes of talking to their service manager
It is the only way forward i think
I have a star scanner and a vw one but i dont care what anyone says they are not as in depth and informative as main dealer ones
The only thing you need to decide is that if its mechanical and has no sensor it might go un detected
You have spent enough its time for a choice as you should never be having all these issues
More than any car i know to be honest
Decision time i think and pay bill and enjoy your g wagon for what 99% of them are
G
Have you tried eurocarparts or kms in uk for a cheap pattern one to try. It might be pattern part but wont break the bank so much
Gaz
There is some good information on the 722.6 auto box here
http://www.benzworld.org/forums/w210-e-class/1463460-mercedes-benz-722-6...
Love the video - you must post it up on its own. Not everyone who would appreciate it will be following this thread.
Yes true
Very funny.
If the speed sensor does not fix it i recon you are ready for a box of matches
I have been following this thread and am glad you finally sorted your problem out. I'm afraid I could add no help as Arnie and G Wagon G obviously know a lot more than I do. I had a similar story a few years ago with our Land Cruiser, yes a Land Cruiser! - never got to the bottom of the electrical problem and eventually had to get rid of it. Never again: I don't care what people say about them. Like you, I like my G and I prefer it over all other 4x4s. Hope your fix is permanent and you can enjoy motoring again. Ph
Happy days at last
As most people said its usually something simple. All the codes and the can bus etc and its just a simple part
I dont care what code reader people have got
Mine was a couple of thousand but is outdated now
Plug in to a main dealer one and there is more info available. Im sure they would not let people know all info
Its true for bmw and vag and merc , ive seen it done as a friend used to work at mercedes
Ohh so simple
Enjoy the g wagon and yes they are something to love once owning one
Yes, in the end it was something simple. They have this theory that when the coolant pump and thermostat was broke this summer, the gearbox oil got so hot that the rpm sensor could not handle the heat, ant stopped working. After this the rpm sensor have been the issue, since it got broken.
But thank you guys for helping me out with both tips and giving me some inspiration to keep on going! It really helped :)
Now i will drive the G all over Norway. Hills and forests!
Hi, sorry for reurecting this old thread!
I am curious about RPM sensor.... are you refering to the Camshaft sensor? Or gearbox sensor behind the gearbox ?
Having similar issues with my G400 thanks
Hi Gooch
Looking at his post below I think he was refering to the sensor on the gearbox.
Yes, in the end it was something simple. They have this theory that when the coolant pump and thermostat was broke this summer, the gearbox oil got so hot that the rpm sensor could not handle the heat, ant stopped working. After this the rpm sensor have been the issue, since it got broken.
Hi Gooch
Looking at his post below I think he was refering to the sensor on the gearbox.
Yes, in the end it was something simple. They have this theory that when the coolant pump and thermostat was broke this summer, the gearbox oil got so hot that the rpm sensor could not handle the heat, ant stopped working. After this the rpm sensor have been the issue, since it got broken.
Ahh missed that somehow- how you doing mate?
Happy New Year!
Hope i get this sorted soon quite annoying at the minute
It was good to read this older post, and watch the prank video.
Nothing replaces experience. It's always the same faults on certain cars/engines. So when someone can share what their problem was, its a good place to start.
Ahh missed that somehow- how you doing mate?
Happy New Year!
Hope i get this sorted soon quite annoying at the minute
Happy New Year to you as well.
Apart from your current issues how are you enjoying the G400 ? I always fancied a G with a V8 diesel, some stories about reliability issues but when you speak with actual owners they don't seem to have any issues. A few nice ones for sale just now at sensible money.
Hi buddy,
To be honest! You prob remember i owned one back in 2007 ish and i sold mine just after 30th anniversay photoshoot we did for mercedes enthusiast and another one in 2011, and now this one. X3 G400’s.
In all honesty i have owned this since early last year and this one recently has gone into limp mode, buying a new speed sensor behind gearbox one and have a new camshaft sensor, should be back kn the road by next week.
They are reliable it does have its faults being overloaded with loads of electrical gadgets but if your hands on then its common knowledge sometimes..... none of them let me down in a major way to date.
Its 2001 - 2004, G500, G400, G270, g320 cdi’s that all had similar symptons being the early ginipigs, main fault were the ecu repairs cheap capacitors in them. Once this was sorted they all run nice!
Cheers
Gooch
Hi mate, your right certain models had thier own fault designs
Thank you!
This is really the area we work around. I had an issue were the battery run flat, and when the battery gives low voltage that might break some of the resistors or the modules. I Was just wondering if it Was something about it that Was a typical fault?