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Discussion Starter #1
First encounter on my 2000 Benz S500. Car will only start after I reset my ECU using my MB Icarsoft. Initially, a dtc code reads "ECU communication failure with your vehicle" hence, I have no recourse but to erase the code and the car will start right away and everything becomes normal. Typical symptom like this, one would normally suspect battery, alternator or starter but it seems it's none of these and it's simply because when I erased the code or reset the ECU, the car will start fine and all systems are working. But once your turn it off and leave it for an hour or so - especially the following day - starting the car will only give a quiet click and lights on the instrument cluster and not even a "clicking" or cranking sound. So far, that has been my routine: get my Icarsoft obd handy and the car is ok. Checked all the fuses and relays but it seems everything is fine. My mechanic told me that the ECU or ECM could be the culprit. Am now thinking of removing my ECU board on the passenger side and send it to a computer exchange company to have it repaired or reprogrammed. But before doing that, any thoughts or ideas are of course most welcome.
 

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2002 Mercedes ML320, Mercedes 190E 2.3L (sold), 2001 Mercedes c320(gone)
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You may have had low power while the scanner was communicating with the module and things were left in an inconsistent state.

One thing I can almost guarantee is if you have someone with Star, they will simply reload the ECU software and car will start right up.

I had experience while running an ECU update, power went low, car wouldn't start. Next day, I got the car connected via cable to my running vehicle and SDS notified me of incomplete programming attempt (so impressive) and proceeded to reload the software. Reloaded. Car started right up.

The blower fan coming high is almost a sure sign of ECU in 'coding' state.



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Fan on high is bad ecu. You may need to do the 4 part swap - key ignition switch , shifter and ecu out of a donor car . All 4 parts must be changed as a matched set from the same donor car
 

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... but try reprogramming the ECU before replacing everything. Cheaper, easier, and may be what you need. Ensure you connect external reliable power, eg: another car with engine running. It takes almost 18minutes to code the ECU and with the fan high, your system will be dead by then, don't attempt without supporting battery power.

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Discussion Starter #7
Thanks for your suggestions, guys, and I'll take note of them. What's really funny is that when I reset the ECU thru my MB Icarsoft, the car runs like new. Quick start and everything seems normal. Even my mechanic thinks it's the immobilizer factor or ECU reprogramming. One reason too why I always carry my MB Icarsoft because once I stopped and parked the car, it's almost certain that it will not start. Will give an update once further tests have been done and if computer has been reprogrammed.
 

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Discussion Starter #8
By the way, I thought resetting the ECUs could solve the problem at one point by following the instructions on videos I saw on You Tube like pressing down the gas pedal for 5 seconds, disconnecting the battery and tapping positive terminal with the positive cable, etc. but none of these worked. Actually, it almost messed up my car's functions like power windows, trunks and soft-closing doors. I do advise caution and extreme care doing those ECU or ECM resetting videos.
 

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Stop watching Youtube.

Go back and re-read noetico’s posts.

And FOLLOW his suggestion.
 

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Noetico said to reprogram ecu - but How can he reprogram ecu with just an icarsoff scanner ?
O sorry, I do not mean with his icarsoft, I meant for him to find a place with the right equipment, ie SDS. Sorry I wasn't explicit I thought it would be implied, sorry


*Looking up at my post I see I stated SDS for reprogramming *


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By the way, I thought resetting the ECUs could solve the problem at one point by following the instructions on videos I saw on You Tube like pressing down the gas pedal for 5 seconds, disconnecting the battery and tapping positive terminal with the positive cable, etc. but none of these worked. Actually, it almost messed up my car's functions like power windows, trunks and soft-closing doors. I do advise caution and extreme care doing those ECU or ECM resetting videos.
That would not be nice, at least to soft reset anything to do with the battery, simply keeping both terminals unplugged for some minutes should do a soft reset.

A reprogram run is deeper, you are actually flashing the eeprom with a fresh or updated program. You need to use sds, and good power should be connected so your ECU doesn't have low power while flashing.

As with any chip flashing, power loss could brick it, but I was so impressed when a scan I lost power on got resumed very neatly by SDS, but then I would NEVER take that for granted.

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Discussion Starter #13
Appreciate your input guys and Neotico has a point. Only a Star diagnostic instrument can really help my car’s DAS system and I apparently do not have one; hence, I have to take out the ECU board and have it calibrated by a company specializing in ECU/ECM programming. But before removing the battery, I think I’ll have to use a battery memory saver to make sure some functions do no go haywire because it could and can happen every time the battery is removed.
 

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Here’s what I’m saying:

Your ECU file was likely corrupted when the power died while it was connected. Now, it won’t start.

iCarsoft cannot fix a corrupted file.

internet myth/quick fixes cannot fix a corrupted file.

Take the car to someone with SDS and have them look at the ECU. Doesn‘t have to be the dealer, but it must, repeat, must be SDS.

the ECU can stay in the car while you do this.
 

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Discussion Starter #17 (Edited)
As stated in my most recent post, I started to look around for a shop that has an SDS system to look at my car. I went to a true Benz dealer in my area here and I was told that diagnosis alone would cost me $200 and that's only to put the car in their SDS. Another shop doing import cars' diagnosis that has a Star diagnostic system told me that they could look at the car after a couple of days and see what my car's problem was. Considering also that they would only do the job after telling me the problem and cost estimate, I thought it's not a bad proposition and therefore told them I'll try to be back after 2 days. Still wondering whether if it's really the ECU that's keeping my car from a normal start, I looked at the forum one last time hoping I could stumble onto something. Curiously, there was a post (where Neotico also had a comment) about the Motronics/Chassis relay wherein the member's car started right up after allegedly cleaning the fuse box wiring or console. And quite frankly, in the passenger side fuse box, I thought the Motronics/Chassis relay would be the LAST one I would suspect to have anything to do with no start, no click and blower fan engagement as soon as you turn on the key. With nothing to lose and after having inspected all the other fuses and relays, I therefore removed the Motronics relay and put a new one in its slot and see how it would go. I also decided to put my MB Icarsoft to see if the ECU code will come out again. Curiously, the Icarsoft did not show the usual dtc code I normally see, so there was no code to erase this time to be able to start the car and interestingly, no sound of the blower fan, too. What was astonishing however was when I decided to start the car; lo and behold, it did right away and all functions were very much in order. What a relief, indeed, but thinking also that it could just be a fluke, I decided to use the car doing errands, grocery shopping and so on for the next two days. The car's ignition system was flawless and the car at this writing is still working like a clockwork. One click and that's all it takes. Once again, thank you guys for your valuable and informative input.
 

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As stated in my most recent post, I started to look around for a shop that has an SDS system to look at my car. I went to a true Benz dealer in my area here and I was told that diagnosis alone would cost me $200 and that's only to put the car in their SDS. Another shop doing import cars' diagnosis that has a Star diagnostic system told me that they could look at the car after a couple of days and see what my car's problem was. Considering also that they would only do the job after telling me the problem and cost estimate, I thought it's not a bad proposition and therefore told them I'll try to be back after 2 days. Still wondering whether if it's really the ECU that's keeping my car from a normal start, I looked at the forum once last time hoping I could stumble onto something. Curiously, there was a post (where Neotico also had a comment) about the Motronics/Chassis relay wherein the member's car started right up after allegedly cleaning the fuse box wiring or console. And quite frankly, in the passenger side fuse box, I thought the Motronics/Chassis relay would be the LAST one I would suspect to have anything to do with no start, no click and blower fan engagement as soon as you turn on the key. With nothing to lose and after having inspected all the other fuses and relays, I therefore removed the Motronics relay and put a new one in its slot and see how it would go. I also decided to put my MB Icarsoft to see if the ECU code will come out again. Curiously, the Icarsoft did not show the usual dtc code I normally see, so there was no code to erase this time to be able to start the car and interestingly, no sound of the blower fan, too. What was astonishing however was when I decided to start the car; lo and behold, it did right away and all functions were very much in order. What a relief, indeed, but thinking also that it could just be a fluke, I decided to use the car doing errands, grocery shopping and so on for the next two days. The car's ignition system was flawless and the car at this writing is still working like a clockwork. One click and that's all it takes. Once again, thank you guys for your valuable and informative input.
Wow this is good news! Weldone! That was easy. Something to learn everyday. Really sometimes making sure all the electronics are clean and optimal is a good step. People will find your post here helpful. Thanks!
 

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Is that motronics some kind of tweak system to fool and control airmatic height? It would be usesful to know if car has some &/%¤/( aftermarket stuff installed which don't belong to merc... these chariots are not made for pimptuning and I am not any more surprised symptoms you are facing.
 
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