hello from mike webb , we have a 1997 e320 with 70k miles ,transmission is in limp , was able to capture a dropout on rpm sensors in the trans with a fluke98 , tried to capture again with 4 channel edge pac tool on sensor outputs + power + gnd , no , posted to I-ATN, + checked fix database , replaced conductor plate & trans filter & fluid , road test , at first no codes then po715 po720 , these codes are for trans rpm sensor or power supply to trans rpm sensors po715 & error in 1 rear wheel speed sensor which the tcm uses as a vss po720 , we can graph output of all above sensors & power & ground to the trans module at the same time with a multi channel labscope called EDGE SIMUTECH , other than a 500ms delay between startup on the rpm sensors from start there is no weirdness, the codes listed are not supposed to light until the rear wheel speed sensors reach 250 hz which should be about 12mph , but the codes comeback at the time of start up everytime , pin 38 which is power to the solonoids in the valvebody pulses a long 100ms then a short 50ms pulse (code 11) then drops to 0 when the key is switched to on , pin 38 remains @ 0 until the next time the key is switched on , this is the limp function of the trans module .there is serial data present @ the data pins in the trans module, we are clearing the codes thru the mercedesbenz dlc located in the fuseblock with a snapon mt2500 & mercedes software, to me the trans module seems to be bad ,but mbdoc thinks the snapon tool may not be clearing the codes from the tcm , the snapon tech people cant tell me yes or no , they are supposed to contact me monday am to verify which it is , from amsterdam ??? the trans module is pn 020 545 88 32 egs siemens, i have the waveforms stored in databases and they can be emailed if anyone is needing to see them to help with diagnoses . disconnecting the trans module overnight changes nothing ,
the trans module is $830.00 thru mercedes and i dont want to replace it on an very educated guess , i like to see a bad waveform or something actually broken , i am not seeing that .... can someone enlighten me and point me in the right direction .... thanks , mike webb , smile