1997 E320, scanner for trans codes - PeachParts Mercedes-Benz Forum

Bigdaddybenz · #1 02-17-2008, 09:16 PM

I have an OBD II, an ACTRON CP9135 AutoScanner Code Scanner....I'm apparently having transmission problems and wanted to ask if there was an inexpensive scanner out there that can read and clear transmission codes for the early 722.6 trans??.....As it appears that my ACTRON scanner cannot read trans codes as it is coming up as "No Codes Retrieved"

My 1997 E320, while driving, suddenly looses it's ability to throttle and the gas pedal becomes completely unresponsive.....If I restart the car, it returns to normal until the next incident occues.

Some posters here describe this as "limp home mode".......I need confirmation that this is, in fact, "limp home mode".......I say this because when this happens, I can shift the trans and feel it lightly go into drive, reverse and all other gears.............but the acclerator pedal remains completely unresponsive, until I restart the vehicle.

My question is: 'Is this actually limp home mode????

All threads that I have read state that limp home mode allows you to drive the vehicle in certain gears under certain circumstances........Again, my engine's throttle remains completely unresponsive until I restart the vehicle.

Thanks a whole helluva lot, in advance!

Arthur Dalton · #2 02-18-2008, 12:31 AM

What is meant by the word limp in this/your case is that the throttle is being deactivated b/c of a siginal fault. [ limp] .
The Module shuts down the Electronic accelerator [ EA module]. So, one suspect could be a false or bad speed sensor or input/output sensor sig from conductor plate in the trans [ b/c that is a fault common to that trans]

..so , scanning the trans is the next step to verify or eliminate that likely possibility.
The "Limp Home " mode/feature is not what is meant by limp in this situation..you have drive by wire throttle and you have NO SIG to EA, so the trans has to be checked for speed sensor output from the trans conductor..................until that is done, you are not going to get a proper diagnosis or even a diagnostic base to work from. You may even have an EA problem, but I would suspect that would have shown a Power train code.
Early ASR traction controlled cars would restrict the throttle responce when ASR kicked in so that there would not be undue torque to the rear wheels..so, whenever there is a throttle responce problem in the pedal action, it is simply referred to as the pedal goes limp..it is just a term used for the pedal and is not the LIMP HOME MODE , it is just throttle responce terminology that is commonly used when there is a throttle problem..like in your case, where one would state, ..."The throttle goes limp"
Don't get hung up on the word limp, go get the trans codes. Once you have them, you will probably be able to find an answer in the Archives by plugging those code findings using the "Search Feature ".

Bigdaddybenz · #3 02-18-2008, 07:32 AM

Thanks for the excellent response Mr Dalton, the extra effort on your part is GREATLY appreciated at the "limp" concept hade me completely teisted!....Now, I fully understand exactly what you are saying and I will proceed confidently with the diagnostic s required.......Everything you said makes so much sense to me now that it's like a lightbulb suddenly went off in my head......I will get the trans codes pulled, hopefully erased and proceed with the repair......I will post my results and hope that they will somehow be a contribution to this forum.....Thanks again my friend, for yet another random act of kindness.....When people take the time to help others it really changes the world for the best and it inspires people like me to help others in any way that we can!......God bless!

Bigdaddybenz · #4 02-18-2008, 08:54 AM

ps, Arthur,........I failed to mention that my ETS and ABS lights come on occasionally.....I figured out what's tripping them as whenever I run over a pothole with my left front tire, these lights come on.......I suspect that the wheel sensors need replacing......Would this contribute to my transmission issues????

Thanks, once again!