Hi, dear Mercedes drivers!
Something bad was happened and on our customers car the selector of the automatic transmission began to fail, periodically lost the current speed. As it turned out, the problem was in the electronic control unit. The matter was complicated by the fact that this electronic control unit, including, gives permission to start the engine.
He invited me to a hunt and help him with the car. Why not?
Those. Put from another machine cannot be wound up. Pity. But somehow by ignorance, as well as an attempt to save precious hundreds dollars (a new selector costs about 900), a used spare part was bought. With the delivery, she cost me about 120usd.
So, installing it in the car, we with the master received a bummer. No dancing with a tambourine (with the old) did not help. With the old unit, the car started up, but the “PW” indicators did not light up. With the new light up, but did not start.
It seemed all predetermined and will help only the purchase of a new spare part. But on the Internet, I’ve seen hints of the possibility of soldering chips with an engine start code. I unfortunately did not find any detailed information. And, without waiting for anything, we took a soldering station and started experiments. Experienced way it was found out that to start the engine it is enough to solder two chips.
I marked them in the picture.
After soldering, the machine is started and the speed is not lost. Veil! The only thing that confused me, (it is possible that this was a glitch of the used unit) did not work the electromagnet to allow switching modes. But I thought, it’s better to have a bird in your hand than a crane in the sky and remove the blocking mechanism. Moreover, in his village with the repair of Mercedes mega strained. Nobody has Mercedes Das manager or Xentry diagnostics.
He’ve been driving for 2 weeks and no problems.