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is the Engine Control Module the same as the Diagnostic Engine Control Module?

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2.6K views 19 replies 4 participants last post by  RKH  
#1 ·
My SL has the check engine light, the Mercedes mechanic says "no codes stored in engine computer, the diagnostic module is not communicating, needs diagnostic module."

I ordered online a "diagnostic engine control module" from a used Mercedes parts dealer (90 day warranty), but I think it is an ECM, the number on it is 016 545 75 32 ASR, it is Bosch with a Mercedes Tristar logo after the bar code.

Before I take this to the mechanic to run codes, I am wondering whether this is the correct part. If the diagnostic engine control module is different, any model numbers or suggestions would be appreciated. Even for this ECM I received, there are multiple model numbers online that look identical.

On mercedesbenzpartsstore.com I see several modules, they all look the same on the exploded view,
Number 015-545-29-32-80 is discontinued, that is the Bosch number the mechanic gave me. I see 012-545-07-32 is available.

I am thinking the what I ordered is a main engine control module, not a diagnostic, even though it was listed as diagnostic.

Any clarification would be appreciated!
 
#2 ·
Diagnostic module is referring to the actual box and port where you plug in the diagnostic scanner. Return what you bought because you bought an ASR computer. If the diagnostic module isn't responding, your mechanic cannot know that there's no codes stored in the ecu (Engine control unit/ computer/module). Clarify with him what exactly isn't responding: either the ecu or the diagnostic module
 
#5 ·
Thanks. Right, I see the "ASR" on the box so will return. I dropped by the Mercedes shop to confirm the part number, and they confirmed that it is the diagnostic module, but the part number they gave me was 1121538579, and the Bosch number is 0261201161,and these are ECU part numbers. Mechanic was gone for the day, but his notes as you say don't make sense; how can you know that there are no codes in the computer ECU history if the diagnostic module is the problem? Will call and get him on the phone tomorrow. At least I am learning the various modules:)
 
#4 ·
The batter is ok I guess, there is no hesitation in starting up. The CEL has been on since we got the car two years ago, but it has been rarely driven by my brother, I just bought it from him. The engine drives fine, great acceleration. When I start up, the SRS light and the CEL light come on, and the SRS light usually goes out in about five minutes, but the CEL is always on. There really doesn't seem to be any performance problems driving the car, but my brother said that in summer it idled at stop lights and temp rose to about 100, he thinks the auxiliary fans may not be coming on.
 
#10 ·
Thanks. As you see below, when I removed the entire lid I could see that this was just a twist off cap for he 38 pin port.
The adventure continues, I have ordered a diagnostic module, but now I don't trust the mechanic, so want to read my own codes and then find another mechanic if there are codes.

Even with the CEL on, the car passed smog test here in Cali last month with no problem, so will be interested in what codes come up!
 
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