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Old 06-21-2008, 10:30 PM
Roncallo Roncallo is offline
Join Date: Oct 2004
Location: NC
Posts: 3,003
Originally Posted by duxthe1 View Post
John, you've got some work cut out for you, if you are determined to use that electronic trans. I really don't understand your desire to use it. You want to use non M/B engine management so the desire to stay strictly M/B shouldn't be a concern. I honestly don't think it is the best trans to use regardless of whether you can effectively communicate with it enough to shift out of first or not. I don't regard it as a very stout piece to start with. It lives behind that engine b/c the power is cut during upshifts and the tranny module softly engages the gears to keep the 12's torque from busting it apart. Without using the M/B hardware with it's software babying the trans you'll find out what I mean. You've got a clean slate, I'd use that as an opportunity to start with something better, even if it is an older design. Mercedes reliability track record over the last ten years makes it evident that they were building cars for profit, not reliability. Just b/c it's newer, doesn't mean it's better.
Actually It may have became a non issue just yesterday. I found a company that makes a stand alone controller for the 722.6. They say they developed this particular controller for the military and that is there only customer so far. I wonder for what. In any case the controller is $750 and the cable is $150. It does not need wheel speed sensors and doesn't talk to the engine. It 's what I call a beautiful thing. They will sell it to me with a satisfaction guarantee. For some reason I get the feeling they want me to develop it for them. In any case that closes the final loop of what to do if I cant get this thing running and have to go with an after market ECU unit for the engine. I now have a transmission solution that doesn't need to talk to the engine and doesn't care about the gear ratio. The older 4 speed MB trans was always the backup plan.

What I am still not sure of, is if this is a plan can put into effect immediately with the existing MB ME ECU's or will I have to go with an after market ECU unit to run the system together. I know the MB transmission control unit sends as outputs over the CAN: internal torque, engaged gear, TC lockup status, overload protection requirement, kickdown and limp-home mode status. I need to ask what would happen if the engine did not see these signals.

So the plan for the moment is to stay the course and use all the stock MB components, and only go with after market stuff if I should run into a problem. I'm actually so close with this I can taste it. Using the stock components also enables me (actually forces me) to have ESP, which is a cool feature I wouldn't mind playing with but it is really making the initial install complex.
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John Roncallo
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