Recent experience with Junction Box module (JBE/JBBF)

fryj00

New Member
Feb 8, 2020
7
3
0
This issue is solved but I thought I would share the info.

So I was getting some weird alerts at random and inconsistently...coolant low, camshaft position (VANOS), windows going crazy, etc. Then, the car suddenly went into limp mode but was still drivable...just with really low power and no boost. The DME threw codes for the following:

quantity control valve short to ground
wastegate solenoid short to ground
both O2 sensor heaters disabled
no voltage on terminal 87_1
charge pressure control switched off as consequence

There was also a blown fuse on F32. New fuse would blow immediately upon switching on ignition

After a shit ton of troubleshooting individual components and scouring wiring diagrams (many of which were inaccurate), I came to the conclusion that the only component that tied all of these different things together was the Junction Box Electronics (JBE) module.It is a complex piece that serves as a power distribution and CAN communication hub. Even the common name is misleading because in my car that module is displayed as JBBF. Anyway, I went to an import car wreck yard and got a used replacement for $150 ($365 retail). I installed the new module, replaced the blown fuse, and coded the VIN to the new module and BOOM!. Fixed.

Wiring diagrams led me to believe that there were differences between N54 and N55 JBE's but if you check RealOEM, its the same module from like 2006 to 2012.

I've attached a pic of the little rat bastard. It's located behind the glove box and just below the fuse block.
 

Attachments

  • $_35.JPG
    $_35.JPG
    7.4 KB · Views: 321

Reformatt

Specialist
Oct 28, 2019
81
41
0
53
Houston
Ride
2010 335i E92
I have noticed slight differences as in the connections on the front my parts car is a 09 E92 335i and my car is a 10 E92 335i my 2010 is like yours above. I will attach a pic of the 09s can you spot the difference..
 

Attachments

  • C647EFB2-56A4-462C-9019-5639BD132844.jpeg
    C647EFB2-56A4-462C-9019-5639BD132844.jpeg
    84.4 KB · Views: 184
  • Like
Reactions: fryj00

fryj00

New Member
Feb 8, 2020
7
3
0
I have noticed slight differences as in the connections on the front my parts car is a 09 E92 335i and my car is a 10 E92 335i my 2010 is like yours above. I will attach a pic of the 09s can you spot the difference..

Yeah, looks like the connections are reversed. Nice.
 

Reformatt

Specialist
Oct 28, 2019
81
41
0
53
Houston
Ride
2010 335i E92
I’m chasing a 2F71 E-Box fan activation. An I’m with you on the wiring diagrams they are crap. My background is engineering I have done my share of wiring diagrams...Just trying to figure out what is triggering the fan to kick on. I guess it’s not a horrible thing that it runs all the time when the car is on...But my OCD wants to know why lol
 

Reformatt

Specialist
Oct 28, 2019
81
41
0
53
Houston
Ride
2010 335i E92
Well the solution for my 2F71 E-Box fan activation code ended up not being a bad fan...I got tired of chasing wiring diagrams cloned my DME that solved the E-Box fan code. I assume my old DME was no happy anymore.
 

fryj00

New Member
Feb 8, 2020
7
3
0
So, as it turns out. my junction box was not the root of my problem. A while back I hit a sharp bump and the problem happened again. Fuse blew (37 not 32) and the car kicked into limp mode again. Still driveable but god-awful slow. Threw the same codes as mentioned above...WTF!

Long story short:
If I replaced the fuse, it would blow as soon as I put it in...so obviously something is shorted to ground.

I unplugged every sensor/actuator that was throwing a code with this fuse blown, replaced the fuse, and starting plugging shit back in until the fuse blew again. Well, what do you know it turns out to be the rear 02 sensor. I unplugged that bitch and replaced the fuse and...voila! Aside from the SES light, problem solved.

Next, I now suspected that the junction box I replaced had nothing wrong with it. I put it back in and am currently running the car without issue with the OE JBE installed.

Summary? This means that the 02 sensor had an intermittent short problem that magically disappeared at the exact time I replaced the JBE. this gave the illusion that the JBE was the issue. Wrong!

Did I mention that I bought a second replacement JBE in anticipation of fixing this issue again? Fuck.