C240 fails to start, how to use carsoft - Mercedes-Benz Forum

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post #1 of 3 (permalink) Old 04-14-2011, 02:19 PM Thread Starter
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Date registered: Dec 2010
Vehicle: 2001 c240
Location: Nigeria
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C240 fails to start, how to use carsoft

My 2001 C240 has had 6 instances over the last 5 weeks where it has failed to start. the first time it happened, the car failed to accept the smartkey following a full turn of the steering while the car was at a stationary position and the engine was off. after a bit of trial and error, a car electrician got it to accept the key and the car started easily. however, the subsequent 4 episodes are quite different. the 2nd time, the car was parked at an AC repair shop and when they tried to start it, the key turns fully, but the car fails to crank, there is a faint click from under the hood (sort of like a relay switching), the headlights do not dim and the fan does not turn. the same electrician came and poked around and got it to start after a while. the next time it happened, i was driving and i just turned on the AC, when the car just died, i attempted to start it but when i turn the ignition fully, all i hear is the fan turning at full speed, no crank, nothing. the fourth time also the AC was on, and it was really a hot day when the car just died.
now from my own research it seems the most likely culprit is the crankshaft position sensor, but the car doesn't start when i allow it to cool, even overnight, the electrician has to come and poke around the relay and fuses before it kicks up. now i got him to change all the relays and most of the fuses but the next day, it still happened.
i didn't post all this while cos i was waiting on my carsoft multiplexer from china, which finally arrived yesterday. i have some other issues with the car such as the fan not kicking on when the ac condenser temp goes up, even after changing the refrigerant temp sensor and getting another, it still does not work. the downside of this is that the AC does not get as cool as it can, also, i keep having issues of leakage of the refrigerant from excessive pressure build up at low speeds, so the AC is only turned on above 40mph. Also someone mentioned somewhere that the operating temp of the engine could be dropped to around 80 - 85 degrees using carsoft, would really like that cos mine operates at a steady 95, the prob is the daytime temp here climbs to about 40/42 so a lot of engines over here get fried, wouldn't want that to happen to mine. finally, when the car kicks in i get 'srs, bas, esp, abs and one more' warnings which i would like to do away with.
but when i got the multiplexer, i found out it wasn't as easy as i thought. i did get the car to connect and i can access some parameters easily such ME, instrument cluster, keyless go, but ABS gives ,cannot communicate with module or not present', so does several others, though when i did a complete system diagnosis, it did access the abs, but didn't list out the codes, just said error present.
so i was wondering, for those quite familiar with carsoft 7.4, how does one use it to reset things like abs, refrigerant temp/pressure sensor, and other errors, is it just a simple deletion? also i thought carsoft would interpret the different error codes, but it seems not to do that, anyways, i haven't had time to settle down and give it a go, but would like some direction if possible. thanks in advance.

Last edited by gangsta101; 04-14-2011 at 04:21 PM. Reason: Not enough details present in earlier post.
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post #2 of 3 (permalink) Old 04-24-2011, 06:13 AM Thread Starter
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Date registered: Dec 2010
Vehicle: 2001 c240
Location: Nigeria
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It shames me to post this here, but after all i did ask for help and a lot of people did look in and probably wondered how they could be of help, so i guess i just have to. I got tired of being stranded with everyone telling me i shouldn't have bought a used benz, i tried using carsoft, but it kept showing all was well with the SAM and ME. so i did the only thing i could do, change out every single fuse and relay, so while i was about to start, i noticed a relay that wasn't supposed to be there, i traced the wiring and saw it was supposed to go to the compressor (always knew the compressor in the car wasn't the right make for the car, it was a sanden that was modified to fit into the car, and it had been giving all sorts of problems since i got the car). well, it turns out that the compressor wire was disconnected while they were working on it the first time this problem started and also at the moment i was looking into it. so i removed the relay and problem solved, car was back to normal. reconnected the relay and the car wouldn't start. i reconnected the compressor wire and the car was able to start.
so i guess i have learned 2 lessons, 1. no matter how much it kills me, i will always go for oem parts whenever i can, and 2. i can trust carsoft, can't diagnose what u do not know about.
so i just shelled out some serious money to get a new compressor, condenser and an alternator (all this stress has really damaged the old ones), and i'm hoping i can enjoy my car for a few months.
also erasing the stored codes under AC got the fan back to working the way it was supposed to.
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post #3 of 3 (permalink) Old 04-26-2011, 01:47 PM
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good to hear u got it working and thanks for posting the fix
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