Key locking flashes

[pitch1]

My W210 AG 7 seater 320 CDI has developed a series of electrical faults which I think are all inter linked.

Firstly the warning lights flash on unlocking the car but not on locking it.

Secondly the interior lights no longer respond to the door opening shutting process, remain off unless manually switched, when they work OK.

Thirdly I do not think the alarm is working.

11 years old but only 72K on the clock.

Have checked the relevant fuses all sound.

I can live with these faults but...................

 

[television]

For the inside lamp check the door pin switch, just a spray should fix that.

If the siren has expired then that will upset the locking and unlocking

 

[brandwooddixon]

The alarm siren often fails ( a mixture of the rechargeable battery failing over time and environmental exposure). It's probably set behind the nearside wheel arch trim. My local MB dealer always keeps them in stock, which just goes to show how often they get replaced.

Try replacing this to see if any of the other faults go away. I replaced mine and my car started to flash and beep on locking/unlocking which it didn't do before!

If the door switch trick doesn't cure the interior light problem then don't forget to look at the interior light mode switch on the roof mounted light module.

 

[dog68]

What is the voltage of the built in batteries?

 

[television]

What is the voltage of the built in batteries?

They add up to 12v and all designs vary

 

[Dec]

What is the voltage of the built in batteries?

7.2v

Dec

 

[pitch1]

Thank you guys I will look at the car when I can and check all your answers.

What a club this is!!!!!!!!!!!!!!!!!!!!!!!

 

[teddyk]

Hi pitch1,

As Malcolm has said, check the door contacts.
I had a similar issue on my 2001 W210 estate whereby the indicators would not flash when locking the car, but would flash when unlocking.

What is happening here is that the car thinks that one of the doors is not closed properly before locking.

Can be caused by:
1.Faulty door switch
2.Door switch not being pushed in far enough by the door.

What I did was as follows:

1. Ensure that the automatic lights switch (in roof) is set to come on when you open the doors.
2. Close all the doors and then for each door, open it and manually press in the (black) door switch pin - the lights in the car should start to fade after a few seconds. If this happens, that means that the door switch is ok.

If you push the pin in all the way and the lights do not fade, then the switch is the problem.

In my case, all my door switches were ok when I manually pushed them in, the issue was that the front passenger door was not pushing the door switch pin in far enough for the lights to switch off - as a temporary measure I taped a coin to the door in the spot where it makes contact with the door switch pin - when I closed the door, the interior lights switched off and when alarming the car, the indicators flash as they should.

teddyk.