2003 c230 compressor coupe
No crank no start everything else works. New battery, fuse #52 not blown still 15amps, no codes, raised car and hit the starter, change coolant temp sensor.
Anything else I need to check!

 

I would check crank position sensor, ground cable to starter. Is it turning over or just no cranking at all?

 

Start enable fuses are 31, 52 & 57. Check all. Check starter relay in cavity S of the front SAM.

 

This is next - thanks I also have a new Crank position sensor if I need to change - last I will try to hot "hot wire" the starter on the car (but I'm not that electrical savvy). Might have to remove and take it to the local Autozone to test
ok got my hands full and hoping is some fuse/relay

Starter relay part # 0025420819 - N10/1KS M271

Thanks

 

Update
OK update the fuse to a 20 amp and swap a starter relay with another one and to no avail
No luck yet

 

Run a wire from the battery to the starter motor solenoid. Lets make sure you don't have a cooked solenoid or starter motor.

Hope it's not the EIS.

 

I will be ok if it s a bad starter or solenoid. I just do not want to be an EIS (crossing all of my 20 finger)

 

Get a piece of pipe or metal bar of some sort, and bang directly on the top of the stsrter, and see if it's turns over.
If it does, the starter is the issue, and likely just the brushes.
With starter in hand it's $25 repair at an auto electrics shop.

How many miles? Somewhere between 100k -150K? Guessing...

 

The Clarkson method is also OK.

 

Update
Checked all fuses related to start the car #57 and #31 are good #52 fuse is good but I'm not getting power to this fuse only. I check the rest of the fuses on the same row and are getting power (check with the check light) in addition I checked all my S type relays and they all check OK triggering when power us presence as well as no continuity with the multimeter.
So my culprit is the no power to #52. should the SAM be replaced? I want to disconnect the ECU to see if it resets? Is there a process to this?

 

Let step back and analyze your whole situation here. Now I am going to assume (and I really don't like to assume when diagnosing ) that when you say no crank no start that the key turns in the EIS and that all the accessories and cluster illuminates...is that correct? Also I will assume this is a US spec vehicle as you make reference to "Autozone"

Further for some terminal designations in my description, please also reference Bosch terminal designations here:

http://www.type2.com/library/identifi/bosterm.htm

So lets begin assuming all previous statements...

We are working on a 2003 203 with M271 that will not crank or start but key turns in the EIS. This confirms that fuse 31 cannot be blown as this fuse provides circuit 30 to EIS, steering column module, and steering angle sensor...check

Now the next easiest check is to remove the relay N10/1kS and take a jumper wire and jump terminal 30 and 87 of the relay socket on the SAM N10/1. This should allow the starter to crank with the key on, if it cranks this confirms the starter, wiring, and fuse is ok. Now you need to look at the two measures listed below. There is one part where you state no power to N10/1f52, that is correct as it will only have power while the key is in the crank position. If it does not crank, then you need to look at what was just mentioned.

I am not sure what diagnosis tool you are using, but if you were using DAS and you have no DTC's but can communicate with ME, then that confirms fuse 57 is ok as this powers the ME and you would have no communication along with many additional CAN codes from other control units...check

Next step using DAS would be to check drive authorization of ME, ETC, ESM, and EIS. All those control units should say yes. If not then ou would need to look into the control unit not providing Drive auth. Assuming that is all ok...check

Now we need to look at the actual values in ETC (transmission). There is one value in particular we want to pay attention to and that is Y3/6s1 - this is our starter relay cutout switch which is part of the contact plate in the transmission. A simple check for this is unplug the round connector at the trans and the vehicle will now start (trans of course will be in limp home mode). This part is known for various failures, but if that checks ok then...check


Hope that helps!

 

One more thing

I have yet to see a failing crank sensor cause a no crank no start. Crank sensor will usually cause the vehicle to die while driving and not restart until the sensor cools. It will however still crank.

 

When hot & failing the CPS will cause a "Crank, no start" situation. Not a "No crank, no start" situation.

I've never seen the electrohydraulic transmission bush cause a starting issue even with leaking O Rings.

amcink ~ just so you understand the handshake & start process:

https://mbworld.org/forums/c-class-w...t-process.html

EDIT: For future reference I have this in the W203 Wiki.

 

Ok, thanks for the details and that is a lot for me to digest.
Let me see if I can communicate better
The key turns with no problem, all lights light up (cluster etc) i can shift the transmission into gear without any problems.
Fuse #52 was checked and found no power to it once the key was turned all the way to the right as if the car starts.
I will have to do the next as mention jump the starter relay N10 ( you mention jump the 87 and 30 but the starter sensor only have 1,2 and 3,5) so I'm assuming is to jump 1 and 2; please confirm
I also will be checking the transmission cut out relay. Need to raise the car to do so
I'm using a cheap HB code reader - no codes show up and the tool is limited to its options therefore just a code reader

 

Hi Glyn,

Let me clarify I'm not saying that is what causes it, I am saying a diagnosis step is to unplug it for diagnosis. Switch Y3/6s1 is the starter lockout switch in park position of neutral it should read open. In any gear it should read closed. When unplug the electrical connector, this creates the open and will allow the vehicle to start. This switch is part of the conductor plate.

All we are concerned with in this step is the electrical contacts.

Correct almost exactly what I said. In the first sentance I forgot the no. Statement corrected.

 

Ok so without seeing actual values you will have to stick to the basic checks. Be aware there may be a point in your diagnosis where you will need DAS.

 

Understood. I tend to leave out things that are very seldom an issue.

eg. 99% of no cranks on the W203 are a blown fuse 52. Underated at 15A.

 

Agreed that the fuse is the common culprit, but as his picture shows the 20 amp fuse is already installed and ok.

So now it is time to have a deeper look...while the switch is not common, it does fail. When searching for the unknown leave no stone unturned.

 

I agree. I believe in complete diagnosis once the few obvious items are ticked. Sometimes difficult for DIY'ers without a Star. Unfortunately dealers these days are lost without a Star & have become parts replacers.

 

MB Tech
You mention to jump 10n/1kS 30 and 87 but the sensor relay S only have 1,2 and 3,5 where 1,2 are the one that trigger the lever to close. Is this the relay you want to be jumped? Thanks

 

Terminal 30 and 87 refer to the circuit not the actual pins. There should be a schematic on the side of the relay. Take a quick look in Google for a diagram so you can relate the pins you need to jump.

Basically terminal 85 and 86 will be power and ground to the energizing coil where as 30 will be battery voltage and 87 will be the switched source...in this case our starter.

 

MB Tech
The attached shows a similar relay (the schematic is identical) the one in the car is actually rectangular (i'll take picture later) and I'm assuming you are referring to 3,5 to be jumped
Please confirm

 

You got it

 

You guys aren't taking me seriously on the bang on the starter thing.
Too bad for you.
It has worked for me on more cars than I can count.
You're looking for an elegant and complex solution to what could possibly just be a bad starter and could easily be diagnosed with a couple of whacks of Lizzy Bordon's Axe.
Guess I'll just sit back and wait.

 

Yep! running an LT lead from the battery to the starter solenoid will soon tell you whether it is an enable & switching issue or a solenoid/motor issue. Simple checks first is my motto.