Hi today the wife and I took a short drive in our 2012 Infiniti EX35. On the way back home and for no reason all the electrics in the car stopped working RE: Heater Fan, door locks, lights, radio, wipers (it was raining) tachometer, speedometer everything, however, the engine continued to run as usual. When able I stopped and when I pushed the "Start/Stop" button everything came back on, I thought it would have stopped the engine but it didn't it turned everything thing l back on. So I started driving back home about 5 minutes later the exact same thing happened again. Once again I stopped, engine still running and pressed the Start/Stop button again and the same happened everything came back on BUT this time the Key light stayed on and the Traction Control stayed on. After that we drove home with these two lights on and made it home. I have an Autel OBD2 to see if it might have some faults but NO faults found as of yet. Please has anyone ever had this happen and if so please let me know. It don't make any sense to me that all the eclectics would stop at once and then come back on when the "Start/Stop" button was pushed.
Thanks in advance
Bill

Power to the cabin takes a completely different path from power to the drivetrain. Virtually all the cabin power runs through the IPDM, BCM, or both. Either of those could be responsible, or you might have a wiring issue to one of them. The IPDM is in the engine box and the power path is relatively short, while the BCM is in the cabin and gets power through an intervening connector. So off the top, my first guesses would be a bad IPDM or a connector problem to the BCM.

Hi and thank you for getting back to me so quickly. Can you maybe help by telling me how I might check both the Body Control modular and also the Intelligent Power Distribution Module.

Thanks

You can find the complete power supply wiring diagrams here starting on page PG-6:
https://www.nicoclub.com/service-manual ... 2%2Fpg.pdf

My suggestion is, next time it malfunctions, leave the engine running and put a test lamp on all the fuses in the cabin fusebox. Record which ones are unpowered, then go back to the WD's and see what circuit and device powers each one that's down. Find the common factor and it should lead you to the source of the disconnection.

Thanks again. I left the Battery disconnected over night and then this morning I did the Test on the IPDM, the one using the power on and then clicking the door switch 10 times and everything seem to work. Then I just started the car up and took it for a 10 mile run with no problems. This sort of thing has happened only twice in the last year and both time it was Pissing it down. Could moisture have anything to do with it I wonder.

Anyway I will do what you said if and when it does it again.
Thanks

Exact same thing happened to me a few years back. Yes, it was moisture. My sunroof drain on the driver side plugged up and flooded the seat well. Somehow it screwed up the BCM/ECU. For me, it was a near disaster, nothing could stop the engine. I had it in my driveway and it overheated and blew a water hose, steam/coolant spewing all over the place. Luckily the ECU must have seen the temperature and shut the engine down before any engine damage.

I fixed the sunroof leak, drained and dried the seat well and fixed the blown hose (sure enough Nissan used a plastic coupler that split). Everything works fine now, except the seat and mirror adjustments no longer work. I did a lot of work debugging, tracing signals and think its the BCM that's faulty now. I've got a junk yard BCM and key and will try to replace it someday, but concerned that I'll have to get my other key fobs reprogrammed. The tech package on the EX35 is cool to use, but a real pain to debug. I can't afford a 2 way diagnostic box...

Anyhow, I've put in a kill switch under the hood from the fuel pump fuse just in case this happens again. Suggest you might consider that too

I had no problem stopping the car I just remover the engine air filters and plugged the air intakes to stall the engine. Works great. But thanks for the input. Are you saying that the drain from the roof passed by the BCU? If so where is it located?

Bill

The BCM in your EX is right under the A-pillar on the passenger side, it's much more vulnerable to water from a leaky sunroof than most other Nissan designs. In addition to that, there are giant Super Multiple Junction (SMJ) connectors in similar spots, in or above the kick panels on both sides. Those carry all the signals between the Main (under the dashboard), Engine Room, and Body harnesses. None of them are water sealed, and rotted-out pins can cause just about any electrical issue you can imagine.

Hi Bill, no the sunroof drain only affected the wiring harnesses under the drivers seat, but the problem it caused was likely the engine not stopping. Really a bad thing when you press the button not to have the engine stop. Did not think about blocking the air intake- when your engine compartment is steaming at you I was in a bit of a panic. Now with a kill switch I won't have to worry, and living in CA is handy to stop car theives.

Thanks Vstar- I disconnected all the wiring harnesses that could have gotten wet and cleaned them out- can't find any rust so thinking that the water short while it was there blew something in the BCM. I replaced the underseat computer (forgot what it's called) and the computer under the steering wheel and the problem remains so thinking it must be the BCM.

I just haven't had the time to replace the BCM with the junk yard one I got, so that's my next experiment. If anyone knows why replacing the BCM module with a different one (I do have the one original key fob that it came with) wouldn't work, I'd appreciate it.

pilotbob3 wrote: ↑

Thu Dec 21, 2023 4:43 pm

I just haven't had the time to replace the BCM with the junk yard one I got, so that's my next experiment. If anyone knows why replacing the BCM module with a different one (I do have the one original key fob that it came with) wouldn't work, I'd appreciate it.

Dunno what kind of car you have, but the BCM, ECM, and I-Key Unit (if it has one) all need to agree on the key code information. So even with a fob that matches the BCM, you'll still get a no-start and need to get the fob reprogrammed to the car. BCM's are never plug-and-play.

Thank you Vegas, then I guess I'll have to find d a mobile locksmith to program when I do the swap.