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Mercedes C240
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Discussion Starter #1
I got a 2001 Mercedes C240 for a fantastic price, however she has some electrical problems (SRS, ESP lights on etc.) and the new battery drains in ~2days. Body and mechanically she is in great shape and drives absolutely normal. I am looking forward to read some threats in the benzworld forums and hopefully I can take care of the electrical issues myself.

I live in San Jose California and maybe I can find some MB enthusiasts to share knowledge as well.
 

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Zotye Auto 1.5T T600 2016
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Welcome to Benzworld
 

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Mercedes C240
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Discussion Starter #4
The battery of my 2001 C240 drained within two days. I did an Ampmeter test and figured that fuse 42 (Airbag warning lamps, instrument cluster) is the problem. (The current dropped from 0.8A to 0.1A after pulling fuse 42) My cluster also shows degradation on top and bottom. I am wondering how I can check if the cluster or Airbag warning lamp is the problem. Any advice is greatly appreciated! I also got a Multiplexer but still need to learn how to use it...
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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The battery of my 2001 C240 drained within two days. I did an Ampmeter test and figured that fuse 42 (Airbag warning lamps, instrument cluster) is the problem. (The current dropped from 0.8A to 0.1A after pulling fuse 42) My cluster also shows degradation on top and bottom. I am wondering how I can check if the cluster or Airbag warning lamp is the problem. Any advice is greatly appreciated! I also got a Multiplexer but still need to learn how to use it...
With star diagnostics simply go into the instrument cluster section and run the available tests.
 

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Mercedes C240
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Discussion Starter #6
Thanks for your reply Eric. I have Carsoft 7.4 and will try this weekend. Ill let you know what I find.
 

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Mercedes C240
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Discussion Starter #7
Eric, I attached is the full diagnostic from the carsoft. It seems that the instrument cluster is ok. However, there are quite a number of codes. Are they sorted by importance? Seems like the steering angle sensor and lateral acceleration sensor and BAS should be the first things that should be fixed. Are there any threats about that? Also do you know where the faulty servos for the Airco are located?
Thanks
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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B1044/1001/1066/1036/1010/1501/1010/1103 Are all related to Under Voltage at 10.5v, this means none of these codes are of any use, the other codes cannot be trusted now.

Clear all the fault codes and normalise everything, windows/sunroof/steering etc, then road test the car and run the diagnostic tests again. For the steering angle sensor (with engine running) turn the steering fully left and right several times and this will normalise the sensor.

Read the owners manual on how to normalise things after a low voltage situation.
 

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Mercedes C240
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Discussion Starter #9
Thanks for the advice Eric. I cleared all codes and ran the car around the block for a bit. No issues on the display. Redid the diagnostic and the results are in the attached PDF. Seems like the BAS is one issue and the flaps/servos for the Airco is another one. However, I don't see anything related to fuse 42 (instrument cluster and Airbag warning lights). It seems to be intermittend. I did a couple amp readings from the battery over the weekend and it varies from 0.2 to 0.8Amps (even after 45min waiting and locking the car). All related to fuse 42 and 0.2Amps for fuse 40 (Teleaid, Telephonsystem). Seems like an instrument won't go to sleep some times.
When I pulled both fuses the current went down to 0.01A.
Thanks for your help. Greatly appreciated.
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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You must fix the battery drain problems first of all, I cannot trust the fault codes whilst you still get undervoltage fault codes.
 

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Discussion Starter #11
Thanks Eric, that is right. But right now I don't have a clue where to start. One more thing, today I went to work and the car wouldn't start at my lunch break. Hooked up the starter battery and went straight to O'Reilly where I did a battery check, seems that battery and alternator are ok. The battery was even 93% charged. What can be the issue that it wouldn't cranck. I don't think that the alternator can charge to 93% in <2miles driving?
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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Thanks Eric, that is right. But right now I don't have a clue where to start. One more thing, today I went to work and the car wouldn't start at my lunch break. Hooked up the starter battery and went straight to O'Reilly where I did a battery check, seems that battery and alternator are ok. The battery was even 93% charged. What can be the issue that it wouldn't cranck. I don't think that the alternator can charge to 93% in <2miles driving?
It seems to me that you have a bigger problem brewing and really need to read out the fault codes before this car lets you down all together. Always best to tackle a problem when it starts to show signs of failure rather than wait until the thing breaks down.
 
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