BSD faults

Michael Technical Support Specialist Commack, New York Posted   Latest   Edited  

BSD in N52, N54 and N55 engines.

BSD ( Bit Serial Data line)

The bit-serial data interface is a single-wire data bus with a data transfer rate of 1.2 kBit/s.

The following components are connected across the bit-serial data interface with the DME control unit:

  • Alternator (varies according to version)
  • Intelligent battery sensor (depending on model series)
  • Electric coolant pump (depending on variant)
  • Oil condition sensor (depending on variant)

DME is master controller 

The first check: ALT, needs to be OEM 

see attachments for various known good scope images from various scopes. 

+4
Steven Mechanic
Spokane, Washington
Steven Default
 

Hello Michael, I have to mention that the picture you attached does not look like a known good pattern. It may be that the scope could not capture the fast signal. I found a good pattern here That image is from this web page picoauto​.​com/library/case-s…

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Eric Mobile Technician
Peoria, Illinois
Eric Default
 

Hello Steven, The snap on capture is flawed not due to scope speed/resolution, it is not setup up correctly- timebase is incorrect. It has WAY too much time on the screen. This causes the scope to alias or "guess" where it should "connect the dots" on the screen This is a common issue with SO users. The scope should be setup somewhere a 50 ms time sweep which is the equivalent of 5ms per

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Steven Mechanic
Spokane, Washington
Steven Default
 

You got it. Thanks Eric. ☺️

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Eric Technical Support Specialist
Commack, New York
Eric Default
   

Steven, Are you authorized to reuse that material without permission from Pico? Is that copyrighted material?

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Steven Mechanic
Spokane, Washington
Steven Default
 

If I need to remove the link to the image, I will. The other link is just to their website that is publically viewable by anyone. It's not a private webpage.

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Scott Manager
Claremont, California
Scott Default
 

I don’t see an issue here Steven, you simply linked to an image on a public webpage which supported embedding.

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Steven Mechanic
Spokane, Washington
Steven Default
 

Thanks for checking 👍

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Timothy Diagnostician
Evans, Georgia
Timothy Default
 

Don't forget to voltage drop the ground circuit. I have seen several of these with the bolts breaking in the passenger side motor mount bracket that the engine ground is attached to. Look at all of the bolts that attach the bracket to the block. Two broken bolts will elevate the ground enough to cause an intermittent issue with the BSD line. Factory or Bosch rebuilt only on the replacement…

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