I have a 2000 SLK 230 78,000 miles. Intermittent no start turn key nothing happens after cycling key switch 3 or 4 time she makes fire. Battery is new cables tight no corrosion. Car died at a traffic light the other day. All the dash lights came on put the car in park she started right up. Help! Possible K 40 relay problem. Thanks

 

I removed the K40 board. I examined the solder joints they all look fine don't see any cracked joints. Can the board still be bad? What should I check next?

 

Started car let it idle for about 45 minutes. It just died all warning lights are on. Tried to restart nothing happens I don't hear any of the relays or the fuel pump priming the system. Cycled key 3 or 4 times hear relays and fuel pump prime and she lights right up. Any ideas?

 

Sounds like the famed K40 relay problem.

 

Or long chance CPS

Bazzle

 

This car has been trouble free for me. This all started after the OEM battery failed. I just removed the battery cables and sprayed them with battery protector spray. I find it hard to believe that this all started with a bad battery?

 

Hi scrmnss,

You didn't mention whether or not the car was "cold" or “warmed up� when you have had the starting problem.

As Bazzle was eluding to, if the car is warmed up and dies and has a hard time starting (or re-starting) then it could be the Crankshaft Position Sensor.

I would go for the Fuel Pump Relay as that's usually the cause of what I believe you to be describing.

Hope this helps

 

The car has not had the intemittent start when it is cold always at operating temp. I don't see how the CPS could be the problem. The car won't do anything when you turn the key you don't hear anything happen under the hood. I am more interesed in what energizes the components when you turn the key to the on position. Is it the key switch, K40 circuit board, or the computer. Why does cycling the key switch 3 or 4 times make the problem go away and it starts right up? I was at the mercedes dealer talking to a tech and he told me he doesn't see the ignition switch on these cars go bad.

 

From your last description, it definitely sounds like the K40 Relay.

If you want to verify the problem.... the next time it does this, try either taking out the relay and tapping it on the side and re-try it, or tapping it with the end of a screwdriver or something similar.

If it fires up after a tap (or stalls) then you know you've nailed the problem.

The attached picture shows the location of the USA version.



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