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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53599
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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230 Kompressor: a 2000 mercedes..intermittently..Battery voltage

Resolved Question:

I have a 2000 Mercedes SLK 230 Kompressor vehicle. Starts intermittently. Battery voltage at rest 12.5. With key in position two all instrument light up, fans run, I believe uunrelated 390 fault code. ??
Submitted: 6 years ago.
Category: Mercedes
Expert:  Marty replied 6 years ago.
Chat Conversation Started
eurotec :

Hi, when you say it starts intermittently does the starter crank the motor but it won't start?

Customer:

Nothing happens with repect to the cranking. When it decides to crank it will start.

eurotec :

Ok, this sounds like a typical failure of the K40 relay module. The module is located under the hood at the right rear in the module box.

eurotec :

Full Size Image

Customer:

Wouldn't this give me a relevant fault code?

eurotec :

Sometimes you can take the module out of it's bracket and tap on it and get the car to start. The fans running is also a symptom of the bad module. You won't get fault codes for the module.

Customer:

Is this a repairable item? How much should a new one cost?

eurotec :

The part # XXXXX XXXXX 540 00 72 msrp is $152.00.

Customer:

Doesn't the K40 contain a number of relays. Which one would be associated with the start problem?

eurotec :

Yes it contains your starter relay among others. I doubt that you can repair it. You can find them online for a little less.

Customer:

Thanks for your help I'll try the disconnect and tap it method first.

Expert:  Marty replied 6 years ago.
Chat Conversation Ended

Your expert is gathering additional information and will be back with you shortly.
Customer: replied 6 years ago.
I did not locate this K40. At my right rear under the hood is a fuse box? Is the location different for my vehicle?
Expert:  Marty replied 6 years ago.

It should be in the box near the battery. I've attached a picture below.

 

graphic

Marty and 3 other Mercedes Specialists are ready to help you
Customer: replied 6 years ago.
I found it.
Expert:  Marty replied 6 years ago.
Excellent! Good luck with it. I'm quite confident that it will solve the problem.