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Engine Management Light on

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by JCP, Nov 18, 2012.

  1. JCP

    JCP Senior Member

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    My 2007 E 320 CDI (W211) struggled to start this morning. I turned the ignition on for what seemed the normal time and then tried to start it, although it eventually timed out without starting. On the second attempt it started although the engine management light came on and a message on the dash saying something like "ESP Problem etc".

    After a 30 mile driver I arranged for the AA to plug in their diagnostic machine and it reported two faults - firstly "glow plug control circuit open" and secondly "crankshaft position sensor".

    The AA cleared the faults and when I tried to start the engine everything is fine and no fault codes are appearing. The engine has been warm ever since is started this morning.

    I'm expecting it not to start correctly tomorrow. All 6 glow plugs were changed about 20 months ago (after one failed).

    On balance I suspect the problem lies with the glow plug control system. Does this seem logical? Is there anything I can do to validate this, such as checking the system control unit etc? Does it need to go to a workshop with Star Diagnostics or is it something I can sort out myself?

    Hopefully you can help.
     
  2. television

    television Always remembered RIP

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    The CPS normally fails when hot,,, but no reason why it not should fail when very cold, this will or can turn the lamp on.
     
  3. OP
    JCP

    JCP Senior Member

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    Thanks for this - is it something I can either take out and check say using a multi meter to confirm the failure, where is it located and how much does a new one cost?

    Once the new one is fitted, does it need "setting up" via Star Diagnostics?

    I'm an ex truck mechanic and happy to rectify as much as I can myself.
     
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    JCP

    JCP Senior Member

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    hanks for this - is it something I can either take out and check say using a multi meter to confirm the failure, where is it located and how much does a new one cost?

    Once the new one is fitted, does it need "setting up" via Star Diagnostics?

    I'm an ex truck mechanic and happy to rectify as much as I can myself.
     
  5. television

    television Always remembered RIP

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    It sits on the bell housing over the starter motor with a 2 or 3 pin connector on top. It counts the teeth on the starter ring

    When good they measure between 800Ω and 1kΩ
     
  6. OP
    JCP

    JCP Senior Member

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    That sounds straightforward - how does the crankshaft sensor failure affect the cold starting capability? It felt as though the glow plugs were not heating, probably not getting any power to them.
     
  7. television

    television Always remembered RIP

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    It does not really other than if the battery was low as the glow plugs pull high current, it could have been a low voltage glitch showing up the CPS, one just never really knows- The CPS sets up the injection system for firing, no CPS and no injection. It may never do it again, one just never knows
     
  8. OP
    JCP

    JCP Senior Member

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    Television, many thanks for your help and background info on this. I'll see what happens tomorrow and if its the same again, I'll take it to the local MB indie and get it sorted.
     
  9. television

    television Always remembered RIP

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    An indie is far cheaper ;)
     

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