Help! My intermittent start failures

I have trouble starting my 1995 W202 C280. From time to time, the engine could not be started but instead the cranking sound from the engine could be heard and both the infrared lights (red & green) on the rear view mirror will start to flash alternatively. I have to keep turning the ignition and the sound of the cranking keeps occurring. Eventually I gave up and took out the key and waited in the car for about 2-3 minutes and then the car would start up back to normal as if nothing had happened.

This case doesn’t happen all the time but I could say this is a hot start problem? It only happens unexpectedly, say that I’m going to the bank for 10 mins and return back to the car and this hot start problem will occur; leaving me to wait in the car for 3 mins before it could start again.

Anyone has encountered this problem in their 1995 C280 W202? I have been told by the dealer to replace:
· New keys
· New battery
· A voltage regulator

I have done these 3 replacements and the problem still occurs! This has been going on for 5 months now.

I am suspecting the alternator or the ECU (I have just installed and programmed my ECU 5 months ago)may cause all these intermittent hot start problems!? I would really appreciate any comments from you guys?

if the green and red flash alternately, it's just the key battery. if both, then the DAS or drive authorization system (key recognition).
just replace the key battery.

if the car cannot crank, then might be the car battery or alternator? if it cranks, then it can be fuel pump or crankshaft position sensor. the gap on the crankshaft position sensor between the flywheel was too wide. replace it with modified part number.

Thanks for the reply Sleepwalker

quote:

ORIGINAL: sleepwalker

if the green and red flash alternately, it's just the key battery. if both, then the DAS or drive authorization system (key recognition).
just replace the key battery.

I have changed all the batteries in my keys and J have already ordered and new key and it has been synchronized as well. It still didn't solve the problem

quote:

ORIGINAL: sleepwalker

if the car cannot crank, then might be the car battery or alternator? if it cranks, then it can be fuel pump or crankshaft position sensor. the gap on the crankshaft position sensor between the flywheel was too wide. replace it with modified part number.

The car cranks but the infrared lights (RED & Green) in the rear view mirror will keep flashing. Therefore it keeps cranking when i turn the key to start the engine. I have to wait for about 3 minutes and restart the car, it will start as normal.

These intermittent problems only started to occur after I installed and programmed a new ECU in my car (the old one was faulty).

Some mechanics say that the alternator may not be charging that cause this problem but i suspect that there may be some faults in the program in the ECU.

You know anyone who has this problem before?


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Sleepwalker,

the 2 images above in my last post were the results that came out on the diagnosis screen. Do you know what they mean?

Thanks

those two attachments are the same.

the first one is the Controller Area Network from transmission to the engine control unit got intermittent problem because the fault was stored and not present or current. this often happens and the fault can be ignored if it doesn't create any driveability problem.

the second fault is about the infrared remote control... that's your ignition key. no reception means that the signal is weak and cannot be recognized by the control unit. i will send you more information about this problem.

for now i got to rest for it is very late where i am. please tell me the VIN or chassis number of your car. i will check every deatails about service informations and the time of production.

Dear Sleepwalker,

Thank you very much for your feedback on the above tiems.

1)

quote:

the first one is the Controller Area Network from transmission to the engine control unit got intermittent problem because the fault was stored and not present or current. this often happens and the fault can be ignored if it doesn't create any driveability problem

Is this fault erasable? I shall be having an appointment with the MB dealer in 2 weeks times. Apparently he does not know about this fault yet.

2)

quote:

the second fault is about the infrared remote control... that's your ignition key. no reception means that the signal is weak and cannot be recognized by the control unit. i will send you more information about this problem

I really appreciate your kind assistance for the further information for No. (2)

I shall e-mail you my chassis number soon. I got dig up my w202 briefcase at home; I'm in the office now. :)


Thank You

while waiting for your VIN number, this might give you something


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Dear Sleepwalker,

Thank you so much for the attachments of the trouble shooting manuals.


The 2nd attachment of your trouble shooting manuals really matched my problem. The other 2 does not really relate, I think? (I may be wrong)

I just want know what is a RCL Control Module? It is something to do with the ECU?

Anyway, this is the first time I get see some specific information and recommendations from trouble shooting manuals such as your posted attachments. Very Impressed! Even the MB dealer in my country does provide such accurate information such as yours. If I am not being rude, may I know how did you get it?

Some mechanics I approached suggested that my alternator is not charging enough to support my ignition. Well, at least your manual makes more sense!
DTC B 1703 (transponder not valid stored); so this fault may can erased?

*I still need your e-mail address so therefore I can e-mail you my VIN number.

Looking forward to hear from you soon.

Thank you.

that's the reason why i send some advance info for your choice. only you knows exactly how the car behaves. only by accurate diagnostic that we can eliminate such problem. at least it gives me an idea on narrowing the symptoms.

RCL is remote central locking. it means your key, the infrared reciever on your door handle, and the transponder on the ignition switch. once i get your VIN and see tha datacard, i will know if your key also send signal by frequency.

where is your country?

i get it from my software called WIS Workshop Information System. it is the only thing that mercedes-benz dealer refer to in everything about technicals. i always get the updated version, and also EPC Electronic Parts Catalog. aiisde from those, i also got complete for all cars like ETKA, ETK, TIS, ALLDATA, TOYOTA, VADIS, Star Diagnosis, GT1 Group Tester One for BMW, Etc. i like the challenges in repairing cars, and i always find the problem in less than two hours at most. it's just the matter of experience, right procedure, and bad mathematics like 1+1=3.

the fault can be deleted, but we call it a hard code because once that green and red light starts flashing, it is stored again.

i still can't find the link with the problem to your alternator. if it is not charging or not cranking, then you got a weak battery that might lead to it. besides, the alternator doesn't give a full charging capacity while you are in the process of cranking the engine.

my email: mygonad@yahoo.com

Hey Sleepwalker,

Check your e-mail, I hope the information is sufficient for you.

Thank you.

quote:

ORIGINAL: sleepwalker

the fault can be deleted, but we call it a hard code because once that green and red light starts flashing, it is stored again.

So can this code be permanently deleted?

I heard from the technician saying that when the flashing lights occur, the computer will automatically erase itself but not permanently as the problem is intermittent so that is why it is hard for them to trace or detect the source of the problem.

If can be permanently deleted, what are the steps or procedures in doing so?

Awaiting your feedback. :)

after a certain on and off of the ignition key, the control unit will delete the fault from the memory if it doesn't occur again. he is right on that one.

you cannot delete it permanently because it simply record the errors for diagnosis purpose.

i'll go and check my email later.

quote:

ORIGINAL: sleepwalker

you cannot delete it permanently because it simply record the errors for diagnosis purpose.

So what is the solution for this problem? If it cannot be deleted it permanently, then these intermittent start failures will keep occuring?

I was thinking whether it is possible to erase all data or information from my existing ECU and reset everything again? Some mechanics say it may work and some said it may not.

Do you know what caused the code DTC B 1703 to occur?

Thanks!

please do the function test and tell me the result. without attending to the car personally and using diagnostic tool might lead to a false assumption.


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here's some more info that might give you some ideas. if the mechanic need any information, i can send them too.

your car was produced june 19, 1995.

i know all the information about it...what you got inside and outside.


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Thank you for the attachments Sleepwalker,

I have some queries though. If you can see that I have highlighted the box in Picture No. 1 and somehow I managed to link it with Picture 2.

In Picture 2, the circled numbers:
12 & 23 --> 1.0-33.0
Fault memory - engine
Actual values

Are the above "hard codes"? Is the MB Dealer able to delete these codes/ numbers and rectify the problem?

Thanks


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okay,let's narrow the problem and make it more simple. study the attachment and you will notice that only very few parts are involved, including the signal.

by the moment you open the door using IFZ, the A26/7 immediately recognize it...agree? ok, NO PROBLEM WITH THE A26/7.

and after that, the door unlocks and the flashing on the mirror indicator is normal? NO PROBLEM WITH THE N54 AND A37!

now, your mind is telling you that there must be a problem with CAN or the wiring from ECM to the starter! YOU ARE RIGHT!

will you believe me right away if i tell you that we need to change your ECM? of course no.

why?

because you want me to do an actual diagnostic test!

NOW HERE WE GO... I AM SENDING YOUR THE STEP BY STEP PROCEDURE TO DO IT (SINCE AM NOT THERE TO DO IT...hehehe)


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test steps....


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let me know the result. it's just a matter of analyzing the faulty area, and anybody can do it.


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wiring diagram.

please pay more attention to theCAN controllers area network.

the mechanic must know how to analyze it.


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Hi Sleepwalker,

Thank you for all the attachments posted today. I guess I will need to do a lot of homework studying these manuals.

It is alright to present these manuals to the mechanic? Anyway, they won't be able to check my car (again!) until after 13th September 2004.

Understanding the abbreviations and diagrams will be a tough challenge.

Thanks

they have the same thing too, but the only problem was that they want to skip the testing and try the trial and error way.

i must admit that i have encountered several similar cases, but without my presence the process might take longer.

the solution i have in mind were:

initialize, synchronize, coding.

wrong or old (not modified) engine control unit installed... (check the part number).

weak transponder ( the sensor around the ignition switch). this depends on how that flashing light behaves, and which key you use, and the actual values from the signals.

how i wish i am there to solve it in just a day... i just can't give premature answer now without confirming anything.

cheers.

Just wondering,

If I were to instruct the MB Dealer to erase the current software in the ECU and re-program all over again, will it make a difference?

They mentioned if they are able to do this, they would require my old ECU to extract "some data" from it in order to perform this operation.

Do you think this makes sense?

they will read the memory from the old ECU, store it in the HHT or Star Diagnosis computer (all the time attached to the car with power, or else it will lose the data), then transfer it to the new ECU. this is the basic procedure, but this not the only thing that we can do with it. check the coding, versions, standard equipments, actual values, analyze faults, actuations, initializations, programming, troubleshooting, etc, etc.

ECU from other cars cannot be used on your car, since it was already interlocked with your car... even the chassis number is written on memory to avoid theft.

the problem could be on the newly installed ECU software version, the person who did it, or the hardware itself.

i would still say it was the service person who did it. he did it right, he did it wrong... only him can tell.

wrong diagnosis also contributes to this.

Thank you for you reply Sleepwalker,

quote:

ORIGINAL: sleepwalker

the problem could be on the newly installed ECU software version, the person who did it, or the hardware itself.

i would still say it was the service person who did it. he did it right, he did it wrong... only him can tell.

wrong diagnosis also contributes to this.

That is what I am suspecting; after repetitive approaches to see this service person (Not an authorised MB Dealer Workshop) responsible for the installation of the new ECU, he finally showed me what came out on his diagnosis screen: picture is below


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Are the results in the attachment posted above symptoms of wrong diagnosis?