[Cameron_H335i]

Hello all this is my first post on bimmperpost. I have quite the electrical problems that have appeared on my 2009 335i since ownership that I bought in January of 2023.

First, I have almost no electrical power. Hazards work and interior lighting works. Windows, door locks, cluster, radio, HVAC controls etc. do not work. I had an issue with my driver window not operating properly and would not go up. Found out it was the FRM had some corrosion in it, changed it, works great and coded with protool with no issues. The next morning, no internal power, not even interior lights or cluster worked, but I could start the engine and drive the car normally, but with no electrical components working. The battery stays on the trickle charger most of the time, holds a charge, has good voltage, and is not that old. The next day, after doing NOTHING, the car has lights inside again and door locks work, but the engine won't even crank. Battery was at full charge. I am a mechanical and electrical engineer so I know my way around what to check but this has me stumped. The car has no history of flooding but I know that it has been slightly abused as I bought it as a project car.

Things that I know are not the issue:
Battery is good
Alternator is good
voltage regulator is good
junction box module is good
FRM is good
Power distribution box(on battery) is good
B+ cable was replaced by the dealership and was not fused to the fusebox

Also before all this happened I was chasing another electrical issue. Whenever I would turn the switch by the steering wheel to turn on headlights, brake lights, etc, the cluster would go dark or gauges would go all over the place, idrive would reset, and the electrical malfunction present warning would show up on the dash. I would lose the ability to operate the lights, but some lights would remain on, even with accessory mode off and key out, car locked, etc. If the car was driving on the road, it would still drive on its own and not even skip a beat. I would turn the lights off, car off, and restart and usually the issue would go away. I checked grounds: all good. I tested each light individually for shorts using protool: all good. I tested the light switch itself for shorts or improper operation: all good. I looked over all wiring inside the car and grounding straps all over the car and found zero issues.

I have found that there was water in the trunk at some point which possibly fried the amp(my radio operates normally but with no sound) and corroded the area around the battery. I took everything out and apart, removed all rust and corrosion, and resprayed to prevent it from happening again. The car sits outside in the rain and I have had heavy rainfall since and not a drop in the trunk. I assume that was from the previous owner.

I removed the fusebox today, took it all the way apart to the internal circuitry and found a few spots of mild corrosion, but I am not sure of that was enough to cause my slew of issues. B+ cable looked fine, it was tough to get off but it did not seem to have fused together. The carpet was dry, but the insulation under the carpet was fairly wet, but the grounds underneath it had not even the slightest bit of corrosion. Again, I have not seen any water leaking down into that section of the car, and the rest of it is dry. I bought a replacement fusebox and B+ cable today and I will update if that solves any issues. I want to see if any of you wizards have something else that I should check or need any more information I will be happy to listen/share. Thank you for any and all guidance.

This is my only car so I need to get it going ASAP

[gbalthrop]

Originally Posted by Cameron_H335i

... 2009 335i ... I have almost no electrical power. Hazards work and interior lighting works.
Windows, door locks, cluster, radio, HVAC controls etc. do not work.
I had an issue with my driver window not operating properly and would not go up. Found out it was the FRM had some corrosion in it, changed it, works great and coded with protool with no issues.
The next morning, no internal power, not even interior lights or cluster worked, but I could start the engine and drive the car normally, but with no electrical components working... The next day, after doing NOTHING, the car has lights inside again and door locks work, but the engine won't even crank... B+ cable was replaced by the dealership and was not fused to the fusebox; Also before all this happened I was chasing another electrical issue. Whenever I would turn the switch by the steering wheel to turn on headlights, brake lights, etc, the cluster would go dark or gauges would go all over the place... I would turn the lights off, car off, and restart and usually the issue would go away...

When Systems or Components do NOT work AT ALL, and then the next day, or after Module "ReBoot", they work normally, that is usually caused by Power Supply issues: Either 12V+ or B+ supply, or Chassis Ground (loose connection). I would suggest begin by examining the B+ supply from the Battery and Rear Power Distribution Panel (RPDP) on top of the battery. There are actually THREE (3) B+ Cables from the Battery:
1) Large B+ cable goes from BST (Battery Safety Terminal) to Outboard Transfer Point in front of Battery Base, and then to JumpStart Terminal under hood, to go to Starter & Alternator;
2) Medium B+ Cable goes from Inboard Rear of RPDP, rearward, up, & over RPDP to go to JB Fuse Panel, cable running INSIDE vehicle;
3) Small B+ Cable goes from 2nd inboard rear of RPDP to Inboard Transfer Point, and then forward to fuse F07 in E-box, powering Coolant Pump on 335i (VVT on N52 Models).

I will attach Photo of my RPDP (3/2007 328xi with VVT) to NEXT post so you can see what to check in each of the 3 B+ supply lines. I would suggest focusing on ONE intermittent power supply issue and dealing with that. I can furnish test suggestions, along with ISTA wiring diagrams and component locations if you will answer the following:
1) What are Last-7 Characters of vehicle VIN?
2) What Make/Model Scan Tool or Diagnostic Software (INPA/ISTA) do you have?
3) What Fault Codes in ALL Modules are shown with ProTool, or any other Diagnostic Software? If there is FF Data or Fault details with DME or CAS Fault Codes, please include that.
4) I assume you have a Multimeter and can follow ISTA wiring diagrams. If NOT, DMM is $7 @ HFT, $10 Amazon.
George

[gbalthrop]

Attached is Photo of 3/2007 build 328xi Rear Power Distribution Panel, along with photos of Transfer Points, per prior post.
George

[Cameron_H335i]

Thank you for your reply.
I have checked a lot of those b+ connections already with both a multimeter, (showing under .3ohms across the cables), as well as a visual inspection. I have not gone under the car to inspect the outside b+ cable from the rear of the car. I will check tomorrow.

I use protool and a KDCAN cable to diagnose, code, and test various functions of the vehicle. Most recently when I checked the codes I had three. One was “C908- Junction Box - K-Can wire fault”
“C91E- Junction box - No message (terminal status, 0x130), receiver JBE, transmitter CAS”
“2DC3 - Engine - monitoring- Terminal 15”

I assume the c91e code is present because I have no ignition and the car is reading the codes while ‘off’ as I can’t turn in on.
C908 code I have had for a little while I believe, not too sure about how long and if it was intermittent it not.

The last 7 of the VIN is P158424
Thanks!

[gbalthrop]

Originally Posted by Cameron_H335i

... I use protool... Most recently when I checked the codes I had three:
“C908- Junction Box - K-Can wire fault”
“C91E- Junction box - No message (terminal status, 0x130), receiver JBE, transmitter CAS”
“2DC3 - Engine - monitoring- Terminal 15”
I assume the c91e code is present because I have no ignition and the car is reading the codes while ‘off’ as I can’t turn in on. The last 7 of the VIN is P158424

I assume your Remote Key does NOT Lock/Unlock doors? If Instrument Cluster does NOT light when START button is pressed WITHOUT pressing Brake/Clutch, then KL15 (Ignition Relay) is NOT being activated by CAS Module as it should. Probably KL30G "Accessory" relay is NOT being activated by CAS either, when that occurs, and you have no exterior lights, Climate Control Panel lights/ function (blower), etc.

ISTA ScreenPrints are attached to NEXT Post, showing the items discussed in this post.

IF that understanding of your issue is accurate, I would focus on WHY CAS is NOT activating the KL15 & KL30G relays on the JB Fuse Panel :
1) Are BOTH CAS fuses (F36 & F55) intact?
2) Is X11010 Connector at Top-Left of JB Fuse Panel plugged in and making GOOD contact (NO corrosion of pins/sockets)?
3) When START button pressed as above (to turn ignition ON), is there voltage to BOTH X11010/2 (Red wire activating IO1068, KL30G), and X11010/6 (Green wire activating IO1069, KL15)?
4) If you apply B+ to either of those two wires, do you hear "Click" of relay on/in JB, and get FUNCTION?

Hope this provides enough info for you to get started and construct your own tests. Please let me know if additional diagrams are needed.
George

[gbalthrop]

Attached are ISTA ScreenPrints related to prior post, including CAS SSP, K-CAN wiring between CAS & JBE connector X14271,
and X11010 Location & Connector View at JB Top-Left, activating KL15 & KL30G when CAS activated (START button).
George

[Cameron_H335i]

You are correct in that my keys do not unlock/lock the doors. However the battery is not that strong and I haven’t driven the car in a bit so I assumed the battery could possibly be dead.

Also, I haven’t messed with the CAS module at all. I have changed the FRM and JBE modules and matched the VIN to the rest of the components(I know that isn’t the problem because issues were solved after replacing the FRM and nothing changed after replacing the JBE). I will take a look at it today and possibly take it apart and have a look inside. Can I supply 12V to the relays to test them or does it need to be 9V? Thank you for the diagrams as well.

[Cameron_H335i]

Attached are some close up pictures of the diassambled junction box. You can see very minor corrosion in some areas. It was hard for me to tell if the b+ cable to the junction box welded itself or not…it was a PITA to get out. I cannot say confidently that this was my issue at all but let me know what you think. The CAS related pins on the circuit of the junction box have the smallest amount of corrosion on the thin sides of about 5 prongs, however none on the long sides where contact is made. I will definitely the connector as well and inspect/clean any corrosion I see.

[Cameron_H335i]

Solved the issue!

I did a few things so I’m not sure exactly what the culprit was but it could’ve been multiple things. First, I replaced the B+ cable to the junction box, as well as the fusebox itself. I checked all the fuses and noticed that I had one unplugged but didn’t look to see what number it was. When I plugged the battery back in and went to start it, it fired right up and didn’t skip a beat!
I then tried to diagnose the other weird flickering/off and on issue I had when I turned the lights on. I turned the lights on, it did the usual, then I turned the lights off, and 30 seconds later I heard something make a little sound and the error went away and it was normal. I unplugged the radio and did the same test and the car operated exactly as it should. No morr flickering, lights controlling themselves, etc. Buying a new used radio to fix that issue!
I’m pumped I was able to get the car going again. It’s a huge relief. A special thanks to George for helping me through this one.