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Roadster starts but immediately cuts out

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  • Roadster starts but immediately cuts out

    We recently had the alternator fail and took a few weeks to get it out and refurbished. Once we had it back in, we started it while up on jacks to check it was working and it ran fine. But now that we've put it back all back together, the car will start, but after a second or two just cuts out. Not getting any error codes on the diagnostics. Any ideas what could be wrong?

  • #2
    Crank position sensor.

    Other than that something wrong with your recent work .... did you fit the original alternator or just get a exchange unit ?


    • #3
      This summer I was helping out with a Roadster that had exactly that problem. Think to remember the cause was bad contact on alternator terminals. Will fire off an email to the owner and seek confirmation.


      • #4
        Get a new /original alternator.
        The refurbished altenator has a wrong part in it.


        • #5
          I had the same problem after fitting an alternator, it was brand new from a specialist electrical supplier but not from Smart/Mercedes. Eventually I decided to buy an original Smart version and this worked OK, however, while I was fitting it I found an intermittent short circuit (sparks) from the alternator/sensor wiring that runs down between the water pump and the gearbox. I repaired this wiring but never got around to retrying the non Smart alternator. So, I don't know if the problem was the defective wiring or the alternator although it stopped every time I started it so it wasn't random. I have no idea what the difference in alternators would be but does anyone want to buy it?


          • #6
            Agree with above - remove the alternator, replace with a brand new (not refurb'd) original smart alternator.


            • #7
              Correct Alternator is Denso DAN521


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