Code p0715 followed by p0748, limp mode 722.6 transmission
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Joined: Jun 2011
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From: Central Coast of California
1997 sl500. 2001 ml55
Code p0715 followed by p0748, limp mode 722.6 transmission
Maybe I can save someone a lot of heartache & cash. Had been getting p0715 (conductor plate/speed sensor) - intermittant stuck in low gear for 2 months. Turn ignition off, restart, shifts normal. 2 months later, Car in electrical limp home mode - stuck in 1st or 2nd gear, period. Easy Change of conductor plate, fluid, filter. Still in limp mode driving to borrow snap-on professional scanner. Reset TRANS codes, was disapointed when car still stuck in low gear... Rescanned, now p0748 (trans solenoid). Pulled trans ECT / TCU, measured infinite resistance (open circuit) between pins 36 & 38 to trans. I was confused since I had the same 'stuck in low gear' problem before and after conductor plate... Pulled plate again, found the solenoid closest to the electrical connector (pressure regulating solenoid I believe) looked like it was seated but when I looked closely I realized that the solenoid was up about 30 thousandths from the plate- this is one of the two solenoids without O-rings and apparently it jammed in the aluminum valve body before seating fully. ( I reused/transferred all solenoids to new conductor plate) Stupid mistake - I was an ASE master for 20 years & should have caught it. Reused the new fluid. I have a 4 post lift so it was easy... As stated in these threads, important TRANS codes show up also as ecu codes and can be read & cleared with cheap scanners from the ENGINE ecu, BUT a high-end scanner MUST be used to clear from tranny ecu / tcm / computer, or code will soon reset on engine computer ("check engine" light). I've seen at least 2 people who had the same issues... This 722.6 was in my 1997 sl500, but this tranny is the same for most benzs from 1996 - 2006.
