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Interior trunk release lamp is permanently lit

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by JRHold, Dec 14, 2012.

  1. JRHold

    JRHold New Member

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    Your Mercedes:
    CLK230K-WDB208- 2000- 2295cc
    Hi, CLK WDB208 coupe, the trunk release switch, on cente console, is permanently lit and frequently shuts down the actuator pump, which I then have to reset by pulling fuses, if left alone for a long time the light eventually goes out until a door or trunk is activated via any means.the locking & unlocking seems to work fine,so think that an air leak in unlikely,Also the micro switch on the trunk release button seems ok,The trunk interior lamp is short circuited but I think this is probably unrelated to the trunk release issue.The only fault code is B1709 Alarm Siren blocked,wrongly coded,defective...I think that this is probably also unrelated...can anyone help please as I am running out of ideas and do not have any wiring diagram!:confused:
     
  2. television

    television Always remembered RIP

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    It could be a leaking actuator in the boot locking,,if the pump has to run too long, then that outlet is deactivated till you pull the fuse, and the process starts all over again. When you lock the boot, the pump should not run for more than a few seconds, if it runs the 18 seconds its timing out
     
  3. Alex Crow

    Alex Crow Senior Member

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    Does it not have a pin switch sticking out from the lower edge of the boot lid?

    That would be the usual cause of this fault, in my experience.
     
  4. OP
    JRHold

    JRHold New Member

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    Pin switch & pump time out

    It does have a switch sticking out from the lower lip of the boot lid, which has four wires on it..this would operate the interior light...if it worked, but this circuit has a dead short. I wondered if this boot light circuit could be connected to the opening mechanism some how...why four wires for a light? (possible alarm circuit I suppose) It does NOT have the air operated lift assist that the cabriolet has.
    The actuator pump only runs for a few seconds...no long enough to time out!
     
  5. Alex Crow

    Alex Crow Senior Member

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    Have you tested the pin switch?
    Does the red light on the switch go out when the pin switch is pressed, as well as the boot light?
    I offer this advise based on previous experience with these specific faults.
     
  6. OP
    JRHold

    JRHold New Member

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    Thanks Alex, unable to check the pin switch/boot light as I have previously mentioned, the boot light has a dead short circuit and so doesnt work, replacement fuse pops instantly ! I was not sure if the pin switch for the boot lamp was connected to the problem with the permanently lit release switch light...but from what you say it would seem that there is a connection.
    I have previously mentioned that the switch has four wires on it (two pairs) & dont know wher the other two go! maybe to the locking/unlocking ?!.......
    looks like fixing the boot lamp circuit fault may be the answer to fixing the release lamp switch issue !
     
    Last edited: Dec 17, 2012
  7. Alex Crow

    Alex Crow Senior Member

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    It may well be a stressed wire that is shorting in the hinge area, where they obviously have to bend.
     
  8. television

    television Always remembered RIP

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    Is there not a switch on these that tells when the boot is closed built into the lock, I will try and get the time to look at the diagrams, for like all cars that have a folding top, if the roof does not know the status of the boot lid it will not work
     
    Last edited: Dec 18, 2012
  9. Alex Crow

    Alex Crow Senior Member

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    I too have not looked at the diagrams for this one, but the boot light fault has to be linked, and is a good fault to chase - hopefully to the conclusion.
     
  10. television

    television Always remembered RIP

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    I have had a look on the diagram and the bot lamp is not any part of the boot closed switches that are all wired to the roll bar ECU
     
  11. Alex Crow

    Alex Crow Senior Member

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    Malcolm, have a look at GF80.20-P-4015A

    It clearly spells out that pin switch S17/8 (pin switch protruding from lower edge of boot lid) is responsible for trunk lid open/closed status, including the red warning light on the switch (which is over CAN from PSE - S17/8 is an earthing switch, and in my diagram, is wired into the PSE unit (as well as the boot light itself, which has permanent live, obviously)).

    I would be chasing that pin switch circuit myself, it is clearly pivotal to to function at fault here, and also apparently has a dead short (according to the OP), so why look elsewhere?

    Unless you know otherwise, this coupe model does not have a roll bar ECU, they are only on the carbriolet models that actually have roll over bars.
     
  12. television

    television Always remembered RIP

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    I took the word coupe to be a 447 soft top :D Thanks I will go to the correct diagram and the correct car
     
    Last edited: Dec 19, 2012
  13. OP
    JRHold

    JRHold New Member

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    Many thanks to both of you for your input..I will persue the boot lamp fault first as it seems too much of a coincidence not to be connected with the initial fault....will advise on the outcome.
     

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