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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3567
Experience:  Qualified Mercedes Benz Diagnostic Technician - 20+ years experience - Workshop Foreman for Mercedes
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I'm a used vheicle dealer. Working on a 98 Ml320 with 85K.

Customer Question

I'm a used vheicle dealer. Working on a 98 Ml320 with 85K. Having transmission issues. Trans get stuck in 1st gear or whatever gear I'm driving in when It acts up(limp mode?). If I disconnect the battery for a while it drives fine, usually until it's restarted at which point it goes into limp mode. When ever it goes into limp mode the bas/esp light and low rangE light start flashing and then eventually stay illuminated, also the yellow oil light goes on/off as well when it goes into limp mode and the temp gauge will intermittanly drop down and then kick back up to operating temp. Yesterday I pulled the 13pin trans connector and it was covered in oil. I cleaned the connector of oil and blew off with compressed air, I replaced the 13pin transmission adapter plug(female part with two o-rings). I also pulled the transmission computer(tcm?) and found no oil present around or inside the module, the one located in above the gas pedal(Siemens module a0225452232). Today, after disconnecting/reconnecting the battery I drove the car about 10mi to my mechanic/friend to have the transmission codes cleared with his snap -on scanner figuring tht might solve my issue. It drove great for a few start ups and then on the way home on the hwy the CEL light came on followed by the flashing low range/bas/oil lights and the car was stick in either 4th gear or overdrive. After restarting the car it then stays stick in 1st gear until I once again disconnect/reconnect the battery. My mechanic/friend cleared the codes before telling me what they were, he just said a bunch of 'no communication with multiple module codes'. When I got home I once again checked/cleaned the transmission 13pin connector although I did not find any oil present this time. At this point I was going to replace the tcm(Siemens trans module)with one from a local salvage yard. If tht doesn't work I figured the next step would be replacing the conductor plate above the valve body. I'd like some advice before I start throwing money/parts at the issue without knowing if it will solve the problem. Thanks for your time and help. -Dave
Submitted: 1 year ago.
Category: Mercedes
Customer: replied 1 year ago.
Cel codes I get are p0700, p0720 and a map sensor code and occasional egr code
Expert:  Marty replied 1 year ago.

Hi Dave, my name is***** look like generic fault codes that were pulled from the engine control module. Any chance you can get the codes from the ABS and Transmission control modules?

Customer: replied 1 year ago.
I can but not until 10am or so tomorrow morning. I don't want to get caught in rush hour traffic with the car acting up. I will get the codes and replay them back ASAP. I'm just perplexed as to the low range/bas/oil light flashing after the cel illuminates and limp mode begins, have you seen this before? Also, the low range motor works, I can put the vehicle in/out of low range without issue. Although Once the cel comes on and the other light start flashing the low range button is no longer responsive.
Expert:  Marty replied 1 year ago.

That's all pretty standard when the transmission goes into limp home mode (except for the oil light flashing). Send me all of the codes tomorrow and I'll help you sort this out.

Customer: replied 1 year ago.
Will do, thank you Marty
-Dave
Expert:  Marty replied 1 year ago.

You're welcome :-)