BMW Coolant Pump LIN bus fault

Jordan Technician Reno, Nevada Posted   Latest   Edited   Bounty  
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Network Communications
2014 BMW 328i 2.0L (N20B20A) 6-spd (S6-17BG)—WBA3A5C55EJ463426
U019F - Lost Communication With Engine Coolant Pump Control Module

Hello gentlemen, I'm hoping someone can shed some light on this fault and the LIN bus/buses on this BMW. The fault is for the coolant pump LIN message missing. The OBD fault number is U019F, the BMW number is CD9010. The coolant has been replaced with a Pierburg new pump (fault was present before coolant pump was replaced). When the coolant pump is unplugged the LIN bus has about a 1 volt square wave on it, and when the coolant pump is plugged the bus stays at battery voltage with a lot of noise. I am having trouble understanding if this is a dedicated bus to the coolant pump, or what other components share the bus. One note refers to it as a B.S.D. that is shared with the alternator and the oil condition sensor. A different diagram show the coolant pump connected to the battery sensor, fuel tank pressure sensor and the air catalyst sensor (this vehicle does not have an ozone reduction radiator). I have unplugged all of the above components except for the fuel tank pressure sensor and there is no change to the bus activity (monitoring with a back probe at the coolant pump). The fault will not clear, and the MIL comes on after two key cycles. Thoughts are most appreciated!! Best, Jordan

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
   

I cant help you on the diagram. I'm assuming this LIN is connected to the DME? If so go to the LIN at the DME an scope it there. If it's good you have what the looks like a high resistance in the LIN wire between the DME an the coolant pump. Everything else functions correctly on the car correct?? If so then your problem is only between the DME and the coolant pump. The 12 volts with the pump…

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Michael Diagnostician
Irving, Texas
Michael Default
 

Shouldn't you be getting 12 volts from the master when the pump is unplugged? 12volts resting.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
   

You should get a 0-12 volt toggle from the master at all times. Plugged in or not. He is getting sort of a square wave with the pump unplugged just not enough.

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Cliff Diagnostician
Santa Maria, California
Cliff Default
   

Anytime you have a LIN bus fault you should check the signal at the module and the component to verify the signal is the same.

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Eric Technical Support Specialist
Huntington Beach, California
Eric Default
   

Cliff, My bad. I was trying to understand the vote tab and thought; if I touch the arrows I would see a tag or comment. I believe that my curiosity cost you one "up" vote. I tried tapping my own arrows first but, that is prohibited. So, I "rocked out with my power probe (PP)" on your arrow. Side note; "Rocking out with my PP out": (PP is an initalism for Power Probe), is reference to the…

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Eric Technical Support Specialist
Huntington Beach, California
Eric Resolution
   

Jordan, I apologize for not reading the whole write up. You have a subscriber of the DME M LIN dropping the voltage when the circuit is complete. Just a quick analogy, Think of the LIN like any other single wire 12V Master/Slave (sub-bus) just like K bus. The K bus had a splice comb that we would remove on line/subscriber at a time and see if the bus comes back up. I am slammed at the moment…

+4 Resolution Ð1 Bounty Awarded
Scott Manager
Warrnambool, Australia
Scott Default
 

Hi Jordan, I agree with Eric on the operation of LIN Bus and being a Master Slave type network the DME will allow space in each frame for response from the slave (coolant pump). As far as I am aware all LIN bus are 12V. The above diagram suggests an internal connection between individual LIN bus circuits at the DME. If after component disconnection the bus is still not restored to 12V you may…

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Mark Diagnostician
Elk Grove, California
Mark Default
 

Jordan, Where did you find that diagram? I have been looking at … and AIR and can not find it.

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Rudy Technician
Montebello, California
Rudy Default
 

Mark- If you follow the path in Jordans AD diagram he posted up, you can find the one he posted. It is the first link "BUS LIN SSP-BTS.........." at the end of his path.

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Mark Diagnostician
Elk Grove, California
Mark Default
 

I am referring to the clip Scott posted showing the DME, water pump, alt, and somthing else in. On my phone and cant see it. He cut it, so I can not see its bread crumb path.

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Jordan Technician
Reno, Nevada
Jordan Default
 

2014 BMW 328i Sedan (F30) L4-2.0L Turbo (N20) Vehicle > Powertrain Management > Computers and Control Systems > Information Bus > Diagrams > Electrical (OE) This is where I found that diagram

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Mark Diagnostician
Elk Grove, California
Mark Default
 

Thank you.

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Eric Technical Support Specialist
Huntington Beach, California
Eric Default
   

Jordan, I appreciate your recognition. I am grateful for being able to offer assistance that. Thank you for sharing this with me. I haven't come back in here to tidy up my statements and; as a group, temper our understanding of this subject. (I got off of a plane several hours ago and I just took some time to read, reflect and recoup, I have been sitting at the runway watching planes come and…

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Mark Diagnostician
Elk Grove, California
Mark Default
   

I think there might be some confusion on which water pump. I have not worked on many F-series cars or any N20 motors...so I am just going to try and relay the BMW info I have available to me. I think everyone here probably can help you with LIN bus better than I. It seems there is at least a possibility of two cooling systems on this car. The "low temp" to cool the air induction system has a…

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Mark Diagnostician
Elk Grove, California
Mark Default
   

Also, I think any reference to BSD is going to be for an N55 motor (6 cylinder). Judging by this attached diagnostics procedure, once you have verified your wire integrity from the DME to the water pump, it would indicate a failed master (DME). Seems you very likely could have an open on the LIN bus wire from the water pump to the DME.

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Jordan Technician
Reno, Nevada
Jordan Update
 

The BMW is fixed with the LIN bus back online. I will post the resolution and award the bounty when I have more time. Thank you for all the replies.

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Jordan: Was this also the cause of your battery code? TIA, Guido

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Jordan Technician
Reno, Nevada
Jordan Default
 

I don't believe so. His battery was low on charge. But the battery sensor is on the same leg of the LIN as the coolant pump.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Sweet!

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Jordan Technician
Reno, Nevada
Jordan Default
 

Thank you Sir!!!!!

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John Owner
Petal, Mississippi
John Default
 

I just had one same issue f30 chassis intelligent power module on left inner fender wall was not sending power to pump it Had Lin line code went through ISTA and followed diag didn’t get anywhere told Me disconnect all lin line components check voltage and on lin line I don’t have water pump diagram in front of me but check the diagram and check power to pump

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Jordan Technician
Reno, Nevada
Jordan Resolution
 

OK, finally back at a computer. Thank you Eric for the LIN bus info and thank you Caleb for your thoughts! I had a good LIN signal back probing at the alternator and the battery sensor. The bad signal on the coolant pump LIN was the same at the DME as at the pump. I removed that wire from the DME connector and the LIN was now good directly at the DME pin 17. So my issue was in the wire…

+10 Resolution Ð1 Bounty Awarded
Thanks
Robert Mechanic
Brunswick, Maine
Robert Default
 

Thanks for the informative thread. Code cd9010 resolved within 30 min 10 inches from pump connector on 2013 x3 n20.

+3 Default Ð1 Bounty Awarded
Jordan Technician
Reno, Nevada
Jordan Default
 

Glad to hear it! You did a lot better than I did!

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