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Bonnet close sensor

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by McDonald, Jun 2, 2019.

  1. McDonald

    McDonald Senior Member

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    Had a great day yesterday at Twickenham rugby. Before setting out I decided to top up the water in the radiator - hot day, sitting in traffic etc.

    On the motorway, RED WARNING bonnet not shut. But it is.

    Where's the sensor that might need cleaning?

    Thanks for any tips on this.
     
    daibevan likes this.
  2. OP
    McDonald

    McDonald Senior Member

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    I've driven 130 miles today. The red warning is intermittant, further suggesting its just a sensor problem. Anyone able to tell me where the sensor is located? The prospect of that long bonnet coming undone on the motorway is not a happy one.
     
  3. vtaylor78

    vtaylor78 Senior Member

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    [​IMG]

    Hopefully this might help.


    Sent from my iPad using Tapatalk
     
    McDonald likes this.
  4. OP
    McDonald

    McDonald Senior Member

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    Thanks VTaylor, much appreciated.
     
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  5. Naraic

    Naraic Moderator

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    The switch for the warning is in the right side (as you face the rear of the car) catch. It's a micro switch. You must remove the catch to access the switch...I had to do this job.
     
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  6. OP
    McDonald

    McDonald Senior Member

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    This irritation has come back. It's booked in with MBS June 2. I hope I don't have to replace these sensors every year. It seems odd that the problem should recur, especially as the bonnet doesn't see much action. I open it occasionally, gaze in wonderment, then close again.
     
  7. John Laidlaw

    John Laidlaw Senior Member

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    annoying....maybe think laterally to fool the car and open and close it more often?:rolleyes:
     
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  8. ajlsl600

    ajlsl600 Senior Member

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    clk3202001,sl6002003 with everything regrettably sold ,A class 170cdi auto. NG/TF1800 ML250
    How did we manage 20 yr ago. If it works great if not bin it. I won't be queuing at Benz for one of these Dtf items. I will just check the bonnet closed before I take off. Simples.......
     
  9. OP
    McDonald

    McDonald Senior Member

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    Drove it to Mercedes Hindhead this afternoon. The Service reception guy came out and had a look. I told him the sensors had been replaced last June. He checked his records and sure enough, they'd changed them (£130.00). He came back out to the car, armed with WD40 and squirted both latch mechanisms liberally. I did the same thing myself yesterday, so wasn't holding out much hope. Driving back up the A3, the problem has disappeared. His WD40 works better than mine.
     
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  10. fatboydel

    fatboydel Active Member

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    I would be inclined to spray it with contact cleaner, rather than WD40....
     
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  11. OP
    McDonald

    McDonald Senior Member

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    I drove it quickly again yesterday to make sure the bonnet warning didn't light up. All good. But I'm reluctant to open the bonnet anytime soon.
     
  12. LostKiwi

    LostKiwi Senior Member

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    I had the same issue with our 230. In the space if 2 months it had random boot separator, boot not closed and bonnet by closed errors. Contact cleaner on the boot separator, the boot latch was (still is) broken giving false alarms though I did fix the alarms, and a LIT of WD sorted the bonnet. All good for three months now (did I have to say that)?
     
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  13. ajlsl600

    ajlsl600 Senior Member

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    The wonderful world of WD40!
     
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  14. Rotorhead500

    Rotorhead500 Senior Member

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    Ahaaa... he used MB-approved WD40!
     
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  15. ajlsl600

    ajlsl600 Senior Member

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    These days, I use a cheap stinky French penertrating oil and keep the good stuff for important jobs!! A tin of wd 40 is around 6/7 euro now.. And for rusty nut and bolts I often use diesel, works good if not in big hurry.
     
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