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R107 W110 R170 W202
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Discussion Starter #1
Hello all

1998 model C180

My fuelflap lock squeeked when locking / unlocking.
I put a bit of oil with my finger onto the pin from inside the boot.

I touched / moved the central locking pump slightly at this time and suddenly it unlocked the car again (was open) by itself.

Thereafter, the central locking would not longer lock the car. The indicators still flashed 3 times but the pump will not come on.

Unlock yes, lock, no.

This goes away if I switch ignition on and off. Everything is normal then, until
suddenly the car will unlock again out of its own or sometimes when I bump the side where the tank flap and pump is.

Thereafter, again, no locking until ignition cycle.


I can't see/hear/or feel any obvious vacuum leaks or bad connections by wiggling the cables/lines at the pump.

What can it be? Can I do more tests?

If I caused this by oiling the tank flap actuator, then what on earth did I do??
I moved it slowly by hand when applying a drop of oil with my finger.
I definitely moved the pump around but that is all.


Best regards
bernt
 

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R107 W110 R170 W202
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176 Posts
Discussion Starter #2
Hello

Hmm, No takers? I am suprised.:cool:

Ok, I removed the central locking pump unit.

This is a Bosch unit.

I opened it and resoldered all the connectors and other non surface mount parts on the board.

I also sprayed the 2 disk operated swtiches + the coenctor pins with contact cleaner spary.
It all looks good.
Put it back.

Still the same. when I bump it or the side of the car, it will suddenly cause the pump re-unlocktop the already unlocked state.

What else can I do?
Should I also resonder the surface mount parts or should I worry more about those 2 disk switches in there?

Regards
Bernt
 

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1997 W202-C180 Classic, smoke silver metallic, Lowered
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271 Posts
Have you checked the vacuum lines?
They can become brittle over time and if you moved it,
it could've damaged the lock line
 

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R107 W110 R170 W202
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176 Posts
Discussion Starter #4
Have you checked the vacuum lines?
They can become brittle over time and if you moved it,
it could've damaged the lock line
Lock Line??
Please tell me more.

Pulling any of the vacuum lines from the pump, does not seem to start it running - like in the problem.

It has 4 conections to the box.
2 single yellow lines, 1 triple yellow line manifild and 1 triple white line manifold.

Regards
Bernt
 

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1997 W202-C180 Classic, smoke silver metallic, Lowered
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271 Posts
Sorry, might've confused it with my Audi which has only 2 vacuum lines out of the pump, I'll check tomorrow to see if there is anything else that could've gone wrong.
Does the pump operate when you try lock it? (From what I've read it still does, which lead me to a broken line)
 

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R107 W110 R170 W202
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176 Posts
Discussion Starter #6
Sorry, might've confused it with my Audi which has only 2 vacuum lines out of the pump, I'll check tomorrow to see if there is anything else that could've gone wrong.
Does the pump operate when you try lock it? (From what I've read it still does, which lead me to a broken line)

thanks.
No. After the first sporadic re-unlock, pump motor will no longer operate for locking. Only indicators will flash 3 times when trying.
Unlock, again, yes, lock, never again till ignition cycle or battery disconnect.

Regards
Bernt
 

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1997 W202-C180 Classic, smoke silver metallic, Lowered
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271 Posts
The only other thing I could think of that you could diagnose is that if there is any power going through to the pump, I'm not a wiring expert so I don't exactly know which is which until a wiring diagram pops up (unfortunately I don't have one).
 
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