No Communication with FEM or entire vehicle

Aaron Owner/Technician Wisconsin Posted   Latest   Edited  
Resolved
Electrical
2014 BMW 435i xDrive 3.0L (N55B30A) 6-spd (S6X45BZ) — WBA3R5C59EK187755
Will Not Key-On

Hey all

I have one that I am nervous to pull the trigger on just yet. Hoping to get your opinion for any checks I may have missed.

Customer was driving the vehicle when suddenly his instrument cluster and iDrive screen went out. Engine was still running. He pulled over to turn it off. When trying to restart, nothing turns on. Vehicle was put into Neutral with the screw on the side of the transmission to get towed here.

There are no key fob messages on the screen. Only the 'N' symbol appears on the dash. I cannot communicate with the vehicle using ISTA nor Autel. The ICOM and J-box both power up as pin 16 does have 12v.

I checked the fuses in the underhood fusebox. All have 12v EXCEPT for the row F42 through F56. Fuse 50 does have 12v as an exception. This concurs with the wiring diagram that terminal 15N is not being powered by the Front Electronics Module (FEM).

I checked OBD pins 6 and 14: Resistance is 60ohms. I have flat 2.5v on both lines when I press the 'Start' button. When I hook up ISTA/ICOM scanner and it tries to communicate on these lines, I get mirroring digital signals, High 2 to 3v and Low 1 to 2v.

I accessed the FEM and checked all connectors: good, clean. Checked all the fuses on the FEM have 12v. Checked both main grounds: 3B-pin6 and 4B-pin33 are both good. Checked that the communication wires both had 2.5v present.

I have not dealt with an FEM before. Should this be like an older BMW with a CAS? In a CAS, you can communicate with the control unit without a key. Have I made all the necessary checks to go ahead and replace the FEM, or am I missing something? If it were an incorrect/faulty key, would the cluster have a key warning?

Thank you all for your help!

Aaron …

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Helpful
Phillip Diagnostician
Alaska
Phillip Default
 

Let me get this straight you have no communication on any module? If that is the case without me actually looking at a diagram did you try unplugging the FEM module to see if communication is restored?

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Billy Mechanic
New Mexico
Billy Default
 

Just suggesting a direction to go in Check basics first, Battery, grounds, pull up power distribution and ground distribution in wiring and check basics (volt drop if possible) the reason I am recommending this because it sounds like either a weird ground problem or a module ( not necessarily the FEM is crowding out the bus.

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Eri Technician
New York
Eri Default
 

Seems like you did your due diligence Aaron. seems like your on the rite track if you load tested the circuits I would be confident but would also recommend if u can isolate the fem from all modules to see if u can communicate with it

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Aaron Owner/Technician
Wisconsin
Aaron Update
 

Hey guys, thanks for the info so far. Problem is, the FEM is the gateway module. The diagnostic port/OBD2 connector is wired straight to the FEM. Unplugging the FEM removes the possibility for tool communication.

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Eri Technician
New York
Eri Default
 

I think 6 and 14 is diag can ,. What if you bench test it to try to see if you can talk to it .being that it’s the gateway I doubt it needs any inputs besides power,ground,and diag can to talk to the scan tool

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Eric Technical Support Specialist
New York
Eric Default
 

Eri, That's great outside the box thinking. That might work. I want to give that a try. You would have to put a 120 Ohm resistor in the harness end (a BOB might be used). I like the idea though. The concept that other modules may be disrupting the communication to the gateway(FEM) is extremely unlikely. Aaron, If you have power at pin 1 of A173*1B (27mm Red cable at the bottom, front of the…

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Aaron Owner/Technician
Wisconsin
Aaron Default
   

Thank you! That makes me feel more confident hearing it from you.

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John Owner
Mississippi
John Default
 

I have a bench test wiring diagram if u would like I actually have adapters to bench test them it will communicate since it’s the gateway let me know

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Zach Technician
Minnesota
Zach Default
 

Just dealt with this on a F30 except my FEM failed with be programming. I would try a battery reset, maybe a hard disconnect just to be sure. Try to bring the FEM back with ISTA programming/coding. If that doesn't work then I would say you came condem there FEM. Just recently there was a DCS message dealing with defective ISTA programming and not being able to correctly program certain F…

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Zach Technician
Minnesota
Zach Default
 

And yes the FEM incorporates your CAS and JBE I think or ZGM. It's a main gateway and a PITA to disgnose when it flakes out. Sounds like you're in the right path for diag.

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

Hey Zach, thanks for the info. That message rings a bell. I did try a hard battery reset first thing, forgot to post that. Yea the FEM does combine a lot of ecus into one. What I was wondering about, can you typically communicate with an FEM without a working key like you can with an older CAS? I have no other F-series cars in the shop right now to try it...

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Mihail Mechanic
Maryland
Mihail Default
 

If you get to the FEM module you can inspect it and its surrounding for signs of water. I find that water is the cause of most euro cars communication problems. If you confirm water got to the module, your diagnostics is pretty much done. Good luck.

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Sam Mobile Technician
Michigan
Sam Default
 

- I think this has been suggested kind of. I would remove the FEM from the scenario. Wire in to the comm lines and determine what you can communicate with without the FEM in the equation. Not knowing where the 120 ohm resistors are in this vehicle you may have to take your results with a grain of salt.

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Rudy Technician
California
Rudy Default
   

My only opinion is to not assume it has 2, 60 ohm resistors in this thing. Many newer vehicles do not go that route anymore, and you may be hard pressed to prove this out(i.e You may not see this in the wiring diagrams and a measurement of the CAN pins may be misleading.....)

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Eric Technical Support Specialist
New York
Eric Default
 

There is a 120 Ohm resister in the harness behind the DLC and one in the FEM. Also to respond to the suggestion that the FEM be removed and an attempt made to communicate with any other module in the Vehicle; It can not be done. The D CAN goes to the FEM and the FEM only. It is a Gateway meaning it receives a request for "communication from the scan tool, the FEM determines the tool protocol and…

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Helpful
Phillip Diagnostician
Alaska
Phillip Default
 

Sorry should of been more clear and did a little more digging. I meant see if communication comes back via scan tool and with a scope. Put resister in the circuit. Since communication with scna tool wont work maybe skip the scan tool part. I just want to make sure nothing else is causing interference with communication.

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Aaron Owner/Technician
Wisconsin
Aaron Update
 

Hey All Thanks for all the great info. I just replaced the FEM with a new one from the BMW dealer. Programmed the vehicle with my ICOM-A and ISTA. I got all nice green check marks during the programming process except for programming and coding the HU-H and the KOMBI. Vehicle starts up fine, runs, drives, no warning lights on the dash. I did a complete scan after taking it on a test drive, and…

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

I should add that a second fault showed up: 801C01: vehicle configuration could not be read. I found the ABL to initialize the flexray. Would not attempt because the vehicle configuration could not be read.

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Eric Technical Support Specialist
New York
Eric Default
 

Aaron, Are you saying that you would not attempt to initialize Flexray? Or, are you saying that the Test module (ABL) would not attempt to initialize Flexray?

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

I tried to but it says vehicle configuration is not written yet. The ABL won’t perform the function until the configuration gets written.

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

One more thing that crossed my mind. I ordered the part on Monday sometime late morning or early afternoon. I was told that this part is treated like a key because some vehicle specific information was to be downloaded into the part. Because if this, the parts counter said it’s going to take 2-3 days to get the part. Well low and behold the part shows up yesterday morning. I was happy and know…

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Zach Technician
Minnesota
Zach Default
 

Hey Arron, Per repair instructions you have to transfer the vehicle configuration from the old FEM into the new FEM. If I remember correctly the procedure reads something to this order. *With the original FEM installed go into module service function and there should be an option of transfer or replacement of FEM module. I don't recall exactly what the service procedure is called. The test…

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

Yea I won’t be able to do that on this car. Absolutely no communication with the old unit. Not sure what I should do next, not do I know the implications of just letting the car go like this. I drove it around yesterday for a while to check all the vehicles functions. You wouldn’t know anything was even wrong. I should probably contact a tech support through ISTA. Does anyone know how to do…

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Paul Technical Support Specialist
Colorado
Paul Default
 

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Eric Technical Support Specialist
New York
Eric Default
 

Aaron, Connect the vehicle to ISTA again and run the Software Update again. If the FEM is not included in the plan there are option to select it and add it to the plan and add a complete vehicle encoding as part of the plan.

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

Yea I did that. It wasn't in the first plan, so I programmed it again finding I could choose FEM replacement. It did encode the FEM. I actually programmed/coded two more times with the same results. It did give me the green check mark next the the FEM encoding. I did start a request under 'contact' this morning, and TISsupport emailed me this afternoon. The only help I got from them thus far was…

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Eric Technical Support Specialist
New York
Eric Default
 

Aaron, Open another Contact through Tis and select Other as the department and request an original VO (Vehicle Order) for that VIN. They will send you a download link. Copy the file to the root of a thumb drive. Insert it into the computer that you are using for ISTA and create a Software Update plan. in the action tabs select, Import VO from external media device.

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

Thanks, Eric! What size thumb drive do you recommend?

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Eric Technical Support Specialist
New York
Eric Default
 

32GB out to be way more than enough

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Aaron Owner/Technician
Wisconsin
Aaron Default
 

Great thanks, Eric. So the customer took the vehicle on Friday, but TIS Support sent me the VO late Friday night. The customer is over in Milwaukee and regularly travels to Madison. He wants to bring the car back soon to have this finished up the right way. I am thinking we will be taking it back in next week. Will definitely keep you guys posted on how it turns out. I really appreciate yours…

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Eric Technical Support Specialist
New York
Eric Default
 

Ok, Download a copy of the VO to your thumb drive and to your desktop. You don't want the link to time out.

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Aaron Owner/Technician
Wisconsin
Aaron Resolution
 

Well thr FEM did fix this car. I was waiting to post a fix, but the customer still has not yet returned for the final programming. I did get the vehicle order on a thumb drive, but customer is in no rush to come back for the last programming because everything is functioning normally at this time. I will post again after we write the vehicle order and initialize flex ray properly. Thanks again.

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Sean Mobile Technician
Florida
Sean Default
 

The problem with the units not getting programmed is the ICOM must have a network switch inline to properly run programming and get all modules updated.

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