1 Malfunction on 2002 Mercedes Benz C240

Check alternator.

Check alternator? I should think the alternator only comes in after the engine must have started and running so that the car's battery could be charged up again and also supports the car's electrics. But not preventing the engine from starting. I may be wrong with my reasoning. I am not familiar with MB though. But???????

People here are trying to help you but if your going to question every idea they will stop.

check alternator is a good start if alternator is not putting out the correct voltage and amperage it will not charge the battery correctly, and so when the engine stops the battery will not be properly charged, and wont be able to turn the engine over correctly

Thanks Pete, with his poor description of the problem, we can only guess. It sounded like a poorly charged battery, alternator is where I'd start. Especially after his question if putting in a freshly charged battery would help. If it is the alternator and he doesn't want to check it, I would recommend just installing a fresh battery every day.

If the engine is not turning over rapidly the battery cannot support the starting power required, which means there will be no power left for all the electrics,

Check voltage with meter when cranking, You will find there is very low volatge.

I bet its below 8 volts

Agreed. Battery replaced with a serviceable unit. Car cranks well as it should during initial starting and stops when ignition is lacking after some few seconds. I believe to prevent draining of battery. At the end the 1 malfunction comes up on the dash.

So what P code do you see now? Any codes that were present before would have been cleared by changing out batteries on the earlier attempts at starting. BTW the ECU shuts down when the input voltage drops below ~9 vDC.

Bob

I don't have any code/s at all. In fact after every attempted start when the malfunction info is displayed I carry out an OBD check and it says No Codes. Am suspecting the ECM might have gone bad since all control especially those that have to do with fuel supply and ignition control come from the ECM. But I don't want to go that end now. Otherwise it will be a very expensive/wasteful troubleshooting if it turns out to be something much less at the end of the day.

For my own info , and something to consider, Does this make/ model vehicle have any protective system to cause the engine to quit on overheat condition? Not that familiar with MB. Could there be excessive drag on pistons etc., causing high current requirement on starter due to overheat condition? Peter I'm hoping you can shed some light on these questions. Thank you in advance for your reply.

h

Yes some models have built in protection ie low oil low oil presure, high temp etc the engine will be protected by the management system, But there would normaly be error codes saying this.

and yes if engine overheats and ecu doesnt protect part of the seizing up would include increased fiction as bearing surfaces start to bind.

and increased piston friction.

one way to find out if the engine is petrol ( gasoline) remove the spark plugs and try to turn engine over by hand it should turn easy, if not oh dear,

The engine turns all the time the starter is cranked but no ignition. After series of attempted starts the OBD11 still reveals no code at all. I believe, if there had been any seizure of part/s the engine would never turn at all.

if there was a partial seizure the engine would still turn but would require a great effort

Thank you again for your prompt reply. More familiar with American manufacturers. Some of these even cancel out cylinders and alternate firing different cylinders to lessen heat generated to help prevent severe high temp damage that could be caused by coolant reduction/loss. Didn't know if MB had such a program although I would like to think they did.

h

To start, in addition to the usual fuel, compression, spark; the Motronic system needs to see the following additional inputs: sufficient voltage to initiate the fuel computer, coolant temperature (to set the initial fuel map), engine speed (to establish TDC), Cam position (to establish ignition and injection timing) and driver recognition from from the immobilizer section of the body control module.

Once the user is authorized, the Motronic unit energizes the fuel pump relay. When the cam position signal appears, the injectors begin to inject fuel according to the coolant temperature, and the ignition portion of the Motronic unit sets the initial ignition timing and the car starts.

Lacking any of the above inputs will prevent starting. Additionally, excessive sparking when changing batteries or charging a battery can induce a large enough voltage spike to destroy the Motronic unit.

Bob

Thanks so much Bob I appreciate. I will give a shot at the Motronic system to see whether its of any good or not. Will let you guys know. Am grateful to you all.

I don't know how far you've gotten in your diagnostic travails at this point, so for the future: the motronic box is very easy to get to; the plug at the motoronic box disassembles quite easily; back probe the wire ends at the connector with a good quality DMM, that can measure AC and DC volts, frequency, ohms, and perhaps square wave pulse width.

Then with the aid a a good schematic you can at least determine if there is signal, voltage or ground for every input and output on the control box. This is easier than trying to find every component at the outset and proves quickly whether there are sufficient inputs to allow proper outputs to make the motor run. If there is no continuity through a component then remove that component (the wire colors will be consistent throughout the circuit) and retest the continuity through the wires back to the computer, through the component, through a replacement component if necessary, then through the circuit from the computer again. In this way as you go circuit by circuit you can eliminate and confirm that each component can perform. If everything is in order and motor still won't start then you can condemn the computer and bite the bullet to replace it. At least you will have confirmed the diagnosis and be sure of some measure of success.

Bob

The basic for start are fuel, compression and spark

Yes. There isn't any ignition. No voltage at the output of the High Tension leads. That has been proven but it seems much farther than that. I don't want any wrong approach in the troubleshooting. That's what prompted my posting. So please how do I go about it. What and what should I check and where do know the component/s located. Thanks ever so much.

Some links to help you.

please answer the following questions

1 what type of engine is it gasolin or diesel

2 is there plenty of water in radiator

3 is there any oil in engine

4 does the oil look ok ie not creamy

5 try starting with side lights on and report back your findings please

6 turn engine over by hand with igniton off and report findings please

and by the way if you dont answer any of the above this will be my last posting on the matter

the following are comments made by you in answer to others postings

I believe, if there had been any seizure of part/s the engine would never turn at all

if you beleive that why ask ?? and by the way your wrong

Agreed. Battery replaced with a serviceable unit. Car cranks well as it should during initial starting and stops when ignition is lacking after some few seconds. I believe to prevent draining of battery. At the end the 1 malfunction comes up on the dash.

do you mean the starter cuts out while you are trying to start it ?

and what do you mean by the 1 malfunction comes up on the dash ?

please describe is it a number 1 or one flash of light ?

some links you may find usefull

http://www.benzworld.org/forums/w203-c-class/1357063-mercedes-benz-2002-c240-battery-electric.html

http://mercedes-benz.mattters.com/tribune/2010/5/20/spy---2012-mercedes-benz-b-klasse

Please Peter don't hands off. I don't know whats happening that's why I posted my snag. Had I known definitely I would not have asked in the first place. So please stay on.

The engine is Gasoline. The oil level was checked before shipment. There is plenty of water in the reservoir.

Well the viscosity of the oil cannot be checked as there is no oil dipstick. I reckon condition and quantity are electronically measured or gauged.

I haven't tried starting with the side lights on yet. But if the engine starts with the lights on, what tell tale is that?

Well the starting is like an electronically controlled sequence in which after some cranking by the starter and no ignition, the starter will cut off.

The instrument cluster has an electronic display that reports any malfunction or next service due mileage. So after every failed start. The statement 1 malfunction is displayed. 1 as in item 1. item 2 could be another malfunction describing some other malfunction. I do hope am clear here.

If you crank with side lights on the engine will crank and the lights will dim slightly but if they go out there is a serious load on the starter, or the starter is faulty.

Its just a quick way of checking volts drop if you havent got a volt meter.

if lights dim really low or go out, the next step is to remove the spark plugs and see if that makes a difference when you crank engine, if not you almost certanly have a seized engine

so if with spark plugs out and side lights on when cranked if the lights go really dim or go out.

And assuming battery is ok then you either have seized engine or faulty starter.

you may also wish to use jump leads from another battery or car.

if the jump leads move or twitch while your cranking you are pulling around 400 amps which is way to high,

Does anyone you know have a multi meter or better still an amp clamp meter that reads DC amps ? if so clamp this on the chassis lead ie the lead from the battery to the chassis then crank and see what the amps are.

@Peter. I have eventually gotten the engine to start and run. Thanks so much to all of you. Now I have the following to contend with.

1. Coolant Temp high even though the engine didn't run for up to 5 minutes. 2. Battery overcharging which is the alternator giving out 16.65V dc. 3. SRS flashing and 4. Lighting/Defective bulb or lights sensor defect.

Now gentlemen whats up with all these? It's now confirmed that the voltage regulator on the alternator is bad. But is there any relationship of that high voltage on the other snags. Please am waiting for your invaluable suggestions.

Error codes for MB

may be of use

http://www.mbclub.co.uk/forums/electronics/964-mercedes-benz-diagnostic-trouble-codes-dtc.html

P0100 Mass or Volume Air Flow Circuit Malfunction ??
P0101 Mass or Volume Air Flow Circuit Range/Performance Problem ??

More error codes.

http://www.bba-reman.com/content.aspx?content=Mercedes_common_fault_codes

Thanks so much Pete. Pete something is telling me that I may just have to do some resetting of trip switch or button. Although the crank sensors mentioned by Oregon will be checked as soon as I get home. All the same, whatever is found would be relayed to you guys. I truly appreciate your invaluable assistance. Thanks once again.

Regarding the engine overheating; if the wires leading to the crank sensor(2 each) were to become hot enought to either short or open, you won't get a signal to the ECM and won't get a fire when you crank the engine. Check to see if you have a spark when cranking, and if not, check the continuity of the crank sensor leads. The crank sensors are mounted at the rear of the engine near the flywheel housing pointing to the flexplate. Or the sensors may have been damaged from overheating as well. Check the wiring and throw in new crank sensor and see if you get a spark.

Don't know if this even applies. Does this year/ model Mercedes use a coded ignition key?

h

Yes it does. Any lead from that point of view?

Don't know for sure if this applies; When we made an ignition key for a vehicle that had a coded key not knowing from looking at the key, The key we made turned the ign switch , cranked the starter , but would not allow the vehicle to fire up and run. The original key allowed it to start . Did someone give you another key not knowing it had to be the coded key for this vehicle to run?

h

The issue is the vehicle was being driven when the whole thing occurred. In fact the driver claimed the vehicle developed an engine overheating condition which I doubt; and got it stopped and never started again. So the code on the key is/was the right code I will assume. I don't know.

Just who was driving the car when it was being delivered? Was it a different person from the gentleman who is trying to get it running. I don't know either!

It was a different person entirely. I am the owner and I truly wish I was around when all these happened, I would have been in a very good position to explain the situation proper. But I wasn't there and was only called to go and pick the vehicle with it's problem/s.

Now the question I would like to ask is that, Does the Metronic system go bad so easily? Because as it looks the Metronic system is what my mind is going to and that could be expensive.

If we assume that the cooling system is intact then a fault occured in the coolant temp circuit or the Engine Coolant Temperature sender, or the cooling fan relay. When the motronic unit read the temperature rise above ~120 C, the it commanded the cooling fan on. Lacking a drop in temperature it assumed detonation, or cooling system failure, and moved the fuel injection full rich. If a temperature drop still did not occur then the motor is shut down.

So if we continue the assumption that the cooling system is intact , then we probe the ECT for signal voltage, KOEO (key on engine off). One side of the sensor should see a reference voltage of ~5 vDC the other side something less. Log the results, Check the resistancethrough the sensor, it should in never be open. The equivalent temp of an open circuit is -84 C. Check the multifunction relay (by the battery) and find and check both the cooling fan and its relay for proper operation.

Once you've rectified the wiring faults the motor should start.

Bob

Mercedes C240 ecu failure is common. The ecu controls the cooling fan so when the fan stays on high speed this usually means the ecu is bad. Here are the instructions on how to remove the c240 ecu part number a1121532679 http://www.mercedesecm.com/remove-ecu.html

MY c320 04 dont start no starter high speed fan