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Mike, Mercedes Technician
Category: Mercedes
Satisfied Customers: 39198
Experience:  Tech Expert
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HI-got an SLK 320 114kmiles-full service history 3 weeks age

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HI-got an SLK 320 114kmiles-full service history 3 weeks age would not start- when you turned the key the fan would cut in and run for 30 seconds followed by a loud bleep -if this was tried for 4 0r 5 times the engine would start.
Just been with a 'Specialist'garage for the last 3 weeks who have admitted defeat. when it starts they have put an ammeter onto it and it shows 2.00 amps on tickover-they then watch it and after 10-15 minutes the ammeter suddenly shows 14-15 amps going in before returning (10 seconds later) to 2.0 amps-they have replaced the battery but cannot find what is causing this massive drain-which flattens the battery in a short time
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Customer: replied 3 years ago.
Yes I still need an answer to the problem
Customer: replied 3 years ago.

I,ve not heard from anyone yet-how long does it normally take to get a reply


Thank you for getting back to me. Unfortunately I can not give you a time frame as we have a variety of Professionals online all the time. However we need to ensure that the right Professional is found to help you. We will continue to look for a Professional to assist you.
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Thank you for your patience,
Hello and Welcome..

My name is ***** ***** Im happy to help / advise...

Im sorry to see you have had a wait - I have been asked to help you with this..

Before we progress - can I just ask if you have had anything electrical fitted to the car etc prior to this happening?

Exactly what have the garage done - ie - what tests and on what have the tested ? What equipment has been used ? Do you have any fault codes for me ?

Please also give me the cars Full reg - and mileage -

Kind Rgds, MIKE....................................
Customer: replied 3 years ago.

Hello Mike

So far they have done a check on their computer which shows 'no fault' they have then doe a discharge test via a multi meter on the battery which shows a huge discharge which flattens the battery within 2 hours- if they leave the engine running it shows a charge of 2 amps and then if they leave it running after some 20 minutes the charge goes up to 15 amps for a short whilst before returning to 2 amp during this they have disconnect the cooling fan

hope this helps



Hi there Gary -

Thank you for your reply and info there..

I do just need to check Gary - these readings... are the for sure "amps".... amp readings ?

Too - Does the battery actually flatten?

Also - what else have they done then by way of tracing the fault down to a circuit / component?

Rgds - MIKE................................
Customer: replied 3 years ago.

Hi Mike

I will check with them on monday and get back to you- the reg No is 32 slk and the mileage is 114k- nothing has been fitted since I had the car -but the battery does flatten completely


Hi there Gary -

Thats fine no problem - just reply here as and when..
To save you time though, your symptoms meantime are that of either the alternator ( circuit ) or computer module intermittent failure.... basically. It can be another component or even a shorted wire on a circuit - but how to find this - as follows.

It needs to be checked for "charge rate" as well at the time when its showing the amp readings up high - switching over to volts to see whats happening there... just in case. But a big drain like that - while running as well, we would start with the alternator on drain test - by disconnecting it and see if the drain stops - if it does, you know that the alternator is the cause... ( They have diodes inside that should only pass current one way - if one or more fails they pass current both ways intermittently , hence you get your drain )

If its found not to be the alternator - then the way forward is to disconnect each circuit in turn -while the meter is on amps test - usually and at first anyway, via the fuses - and again - looking for the amp drain to stop - when a fuse is pulled... When it does, again you have found the circuit that the drain is on.. If its not found by fuse pulling, you then go on to disconnect a circuit at a time - computers / modules and so on until its found.
So thats the way to get to the bottom of this Gary..... and to be honest - while I know you have used a MB specialist - these jobs are usually best trusted to a good auto electrician... just a tip there.

Again by all means get back to me as above - but that is the way to get this sorted for you properly Gary...

Im very pleased to have helped you - Do let me know if you need anything more --

*** Meanwhile - - >>>> Please do click on the "OK/ Excellent ratings" for me - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Kind Rgds, MIKE.
Mike, Mercedes Technician
Category: Mercedes
Satisfied Customers: 39198
Experience: Tech Expert
Mike and other Mercedes Specialists are ready to help you
Customer: replied 3 years ago.
Hi Mike

I,m told that the problems seems to be with the immobiliser?I will let you konw the final verdict (when the cars running ,that is.thanks

You're very welcome Gary -

All the best... let me know if I can help..

Best Rgds, MIKE