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Alright guys. Need some of your help here. I'm new here but been in the performance car/truck world for over 20 yrs. This isn't my first AMG either as I had a W202 C43 that I bought cheap, fixed and sold (regretting selling it to this day) and a CLS63.
Im having the "stuck in 4th gear" electronic limp mode from time to time. It has thrown a code only once. (P0705) prior to me doing the work described below.
I did the connector plug/adapter, trans conductor plate, new fluids/filter, inspected the TCU (bone dry) and it seems to have not solved the issue. I drove it home from the shop, then to work (50 miles) the next day and everything was fine...problem solved........NOPE....then on my way home it went into limp mode again (maybe 5 miles from my office after start up). I pulled off, restarted the car and it was fine again (no codes), drove home in manual mode and tested pulling on the ignition key (I used to have a decent amount of keys on the key ring and thought it may be doing a "General Motors" and disabling an ignition connection) and it was fine, I couldn't reproduce it.
I'm concerned that the typical stuff didn't fix the issue and the TCU appears bone dry. The only thing left is the actual shifter. Am I missing something?
Honestly, I would take it to a shop or someone that has a Star diagnostic reader. I didn't have the 0705 code, but I had gotten the p0715 for a bad conductor plate.
Even after replacing the plate at home, fortunately I had a friend who had a star reader so could diagnose and clear the tranny code.
Other than my .02 cents, I honestly have no other clues.
Hopefully another member who has experience with this code or tranny can chime in.
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