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Discussion Starter #1
Well, looks like something else will be "new" soon under the hood of my old girl....

Went out this morning and the car will not crank. Turn key, get all lights and sounds and a rapid clicking sound. Car will not turn over at all. The battery is at 12.3V without jumper cables attached and 12.5V when the big Dodge Ram is cabled to it. Still just clicking and no turn over.

Have had the battery cables on and off all summer so I do not think it is corrosion on the cables. They "look" fine.

So now I am off to locate the K40 relay and pull it. However, there have been no intermittent cranking problems up to this morning and most of what I have read about the K40, there are intermittent starting problems to begin with.

So next up is the starter or the solenoid. Is that something that can be tested? Is it a DIY replacement? Where is the starter located on the 320? I know the 230 is laid out completely different than the V6 so I am hoping someone has some knowledge of 320 starter location.

Anything else I should be checking?

Thanks
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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Well 12.3V is pretty good... how old is the battery? I'd check for voltage drop between battery + and starter +.

It's hard to tell if a battery cable is "good" with a visual inspection.
 

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Yes I agree get someone to connect a multimeter to your battery whilst you try and start the car and see what the voltage drop is. Normal voltage should be 12.6V. When cranking the engine it should not drop below 9.5volts if it goes under that then you need to try a set of jumper cables from another car if it will crank and start then you need a new battery. If that don't do it then it's either a bad wire/bad connection/solenoid or starter motor.

There's ways to test them all using a multimeter but try the above first and let us know what happens.

Good Luck
 

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I may have read it wrong but if the engine will not crank at all then I don't belief it can be a crankshaft sensor unless these engines are not the same as any other. If it was the sensor the driver should see

1) A Check engine light

2) Stalling and Backfiring when it was running

3) Engine Vibrations


Easy way to check the starter without a multimeter first turn on the headlight get someone to watch them try and start the car if the lights don't change then I'd say NO POWER getting to the starter. If they do dim then you more than likely have a a bad started.

:Beer:

I just tried my SLK320 and have a 2 volt drop only when starting the engine and the head lights dim until the starter disengages.

I will be suprised if it is a Crank case sensor but you never know..
 

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Registered 2009 SLK200
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Crankshaft sensor will have nothing to do with why an engine will not crank / turn over .

It picks up a pulse etc as such . :tu:
 

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Discussion Starter #8
Went back out to test the drop in V when turning the key. Insert key, turn. No lights, no click, no nothing. V still reads 12.33. Once again hooked it up to the Dodge to jump start. This time, got all of the lights and sounds and the clicking is back. Never had a battery so dead you could not jump start it.

So here is the question: Can a battery have voltage but the cranking amps be so low that the car wont jump start?

Battery is 6 years old. Will take it out and take it to store to test tomorrow. Hope that is really what it is.

Chicky, replaced the CPS about 5 years ago. As I recall, when it failed it did not do so all at once. Sometimes it would crank and others it would not. I also don't recall if there was a clicking noise. I seem to recall that all the lights and such would work but when you turn the key, there was no clicking. Almost like when you try to crank it and it is not in park. Someone else that has had a CPS go bad can refresh my memory on what happens when the CPS fails and you turn the key. Clicking or No noise. Thanks for the leads to follow ;)
 

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I had exactly the same problem with mine yesterday, for the third time in as many months. However, I know what the problem is with mine, it just doesn't get used enough! Anyways, like you, I hooked up my other vehicle to it, but it doesn't make much difference. HOWEVER, if I rev the other vehicle whilst it is attached by the jump leads (I put a brick on the throttle!) to my 320 for 5 minutes (and not less) then it will start. I will have to bite the bullet now and take the battery off the car and charge it correctly..... and go for a few more long drives! Good luck.
 

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I have had cars in the (distant) pass that showed these symptoms - the cause was bad battery cables (positive and negative).

Try the following steps - stop testing when the car starts :)

1) Replace battery with a known good battery - it doesn't have to be the 'right' size, just the correct post orientation (positive near the firewall) - if it starts right up, go to MB (or Autozone) and buy a battery - note that the MB battery is not all that much more expensive than one from Autozone - and it says MB ;)
2) Take battery cables off, clean them well and reattach - try starting again.
3) Replace Battery Cables
 

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Discussion Starter #12
What is an inhibitor switch and where is it located? I have not seen that part mentioned anywhere in regards to starting before. What does it do?

Thanks
 

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its in your gearbox and only allows the engine to start in park or neutral a good mechanic should be able to unplug the connecter and bypass it to test if that's your problem. don't be tempted to just run it with it just bypassed tho
 

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Discussion Starter #14
Update. Took battery out and had it tested. Battery is good. Voltage is 12.37 and Cranking Amps are 771 (rated for 700) but is low on charge.

So have it set up on a trickle charger for now.

Follow-up question:
1) Could it be the starter and the repeated attempts to crank the car drained the battery? Could that be the cause of low charge?
2) Does this rule out bad cables?
3) If after the battery is charged and I get it cranked, does someone have a test to find out what the parasitic drain might be? Is that something that an AutoZone would be able to do?

Simprof- did not get a chance to try the headlight trick before the battery was removed.
 

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Registered 2009 SLK200
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By all means check your charging rate !
As if the altenator is under charging that can give you flat battery syptoms .

When you get car running check charging rate output that your altenator is kicking out . :tu:
 

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Discussion Starter #17
Good news. A few hours on the trickle charger and she cranked right up. Now to find the parasitic drain. Any idea where to start? Specific steps would be welcome.:biglaugh:
 

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Remove the negative side battery cable from the negative battery terminal

Connect the black wire to the com input on the multimeter and the red wire to the 10A or 20A input on the multimeter. the meter needs to be able to read at least a 2 or 3 amps for this test to work.

Attach the multimeter between the negative cable and the negative battery post. Wait a few seconds to several minutes for the car to go into sleep mode - i.e. when you make the contact with the ammeter, the cars computer systems "wake up". After a bit of time they will go back to "sleep".

If the ammeter is reading over 25-50 milliamps, something is using too much battery power

Go to the fuse panel(s) and remove fuses, one at a time. Pull the main fuses (higher amp ratings) last. Perform the same steps for relays found in the fuse panel. Sometimes relay contacts can fail to release causing a drain Be sure to observe the ammeter after pulling each fuse or relay.

Watch for the ammeter to drop to acceptable drain (below 25 milliamps). The fuse that reduces the drain is the draw. Check the owners' manual or service manual to find what circuits are on that fuse.

Good Luck it can be a pain..:tu:
 

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Before you start complicating things whats your charging rate output on vehicle first ??

And is your battery a good one ??

You may have a dead cell going on your battery ??

Once they check out all good then you look for a battery drain !

ie an aftermarket electrical device you recently wired up to your car ?
Interior light left on ?
Boot light not going out ?
New stereo added draining ?
A bluetooth device ?
 
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