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SMG won't go into gear at random times

Discussion in 'E46 M3 (2001-2006)' started by gregmoyle, Jan 28, 2013.

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    gregmoyle

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    My 2002 M3 has 80K miles on it and about two years ago the SMG started randomly not shifting on command, with the display blinking the selected gear. I happens in in any gear sequence and without warning. It will happen more frequently if shifting above 4500 or so RPMs. It won't happend for days and then it happens and can happen more than once on the same day. I wait a up to 5 seconds or go up a gear and it will engage. Quite unsettling at times. Dealer looked at it over two years ago and said I needed a new SMG. I've been living with it since, not a big deal, but its keeping me from trading or selling the car for a new 535i. Any suggestions out there?
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    MGarrison

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    Trade-in? Fixing or replacing SMG's sounds expensive...
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    • Technical Service Advisor

    charlson89

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    Well it sounds to me like the SMG pump is failing quite a common problem for this vehicle. This is of course with out properly looking at fault codes. Yes it is a expensive repair, but you dont have to replace the entire transmission. A SMG transmission is really no more than a manual transmission with a electrohyadraulic shifter. You command it to shift and actuates the correct hydraulic system to select that gear. The pump and pressure sensors in your vehicle may be getting weak, so when you command the gear to change it take a little while for the pump to build the pressure to actuate the shift. This repair will have to be done on all SMG 2 vehicles sadly to say, thats whats been keeping me away from them.
    CSBM5 likes this.
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    PUKKA1948

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    Hi, I am having a similar problem with my 03 M3. The SMG will decide to drop out to neutral sometimes. Anyway I was talking with a BMW mechanic, an friend. He diagnosed my car, did some tracing and trouble shooting then told me about the same thing as above. I may need to replace the pump. Then he told me to try replacing the Transmission Oil Temperature sensor. Because of it's location, just below the headers, it may have just gotten tired. So I replaced it, cheap fix. Well so far so good she stays in gear throughout the entire range under any conditions. Hopefully that'll do it rather than the $2500 for a new pump. Rebuilds have been unreliable. Also I placed a 3.3K ohm resister in series with the sensor to fake the AMG out to think it's running cooler than normal. This fix has worked so far, hopefully forever. OR maybe if someone out there has a pump to sell that is absolutely working great, I'd like to talk with you. I have some money..........
    CSBM5 likes this.

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