Hi Y'all, I'm new to this forum and need help. I would like to ask for some suggestions and/or recommendations about the electrical issues that I've been experiencing in my G37 coupe. About a week ago, I was trying to swap the stock non-Nav head unit out for a Nav head unit. Gave up about half way through and put everything back together in the exact order that I took out, all the harness that unplugged were plugged back into the place that they supposed to be.

I disconnected the battery before taking head unit out and when I put it back in, I reconnected the battery and initially, the car starts right up, with all electrics functioning as usual. And then about 30s later my dashboard stops responding to any press of the buttons. I then turn off the car and turn it back on, and my dashboard is still not responding, but this time, my gauge also throw a bunch of lights. So, I tried to turn my car off again, but this time, it won't turn off. I tried pressing the button again and again, it still didn't turn off. I was too much in a panic to pull the fuel pump fuse or find out about an emergency shutdown so I blocked the intakes to shut it down.

I then do some reading online and found out that it was the BCM damaged from a water leak in the passenger foot well, I then realized that my car's passenger foot well was soaking wet every time there is a heavy rain. So, I was sure that it was the failed BCM. But then I found a short on youtube stated that the 10amp fuse was blown due to the owner the car in that video trying swap out a radio ended up with all the same issues that I have now; non functioning gauges and dashboard, having to hold the start/stop button for a few seconds to initiated emergency shut down to turn off the car.

The reason why I am now unsure about the issues of my car is because from what I can find, a failed BCM usually also cause the key to not work and the headlights or taillights not turning off which will cause the battery to drain out. But my key still working, it locks and unlocks the car fine. My dome lights still works as usual. My headlights, taillights, turn signals and hazard lights are still working as usual. My central lock works, too. The car drives normally, the gear changes are normal it accelerate as normal. The only thing wrong while driving is that the car does not lock automatically at speed of about 12 MPH like it was before. The shifter cannot shift out park without poking the shift lock whole and the amber light that indicates the gear positioning at the base of the shifter, which were supposed to only light up one gear positioning that the shifter is in, always light up D even when the shifter is not in D, although this might have been unrelated.

Aside from failed BCM or blown fuse, are there any other possible cause all these issues, I did checked the fusees but only the ones that are related to BCMs and they all looked fine, I'll do a more thorough check in every fuse once I have time and voltage meter. But if y'all have any other suggestions on anywhere else to check or diagnosed, please let me know, they would be very appreciated.

 

What exactly does that mean? This swap is NOT "plug-and-play." Did you change ANY of the wiring?

Are you 100% sure? It is VERY easy to mix up connectors and plug them into the wrong slots. Specifically when it comes the UMAC amp (plastic white box on the headunit. There are two connectors wrapped in yellow tape that MUST be plugged into the amp else a ton of issues will pop up- which sounds exactly like what you are experiencing. Reference this thread as it has pictures and shows what I am referring to.

 

I bought an OWC upgrade wiring harness adaptor to swap the head unit. I have all the parts that is needed for the conversion. But like I said, I did not finished. I'll check again and see if I plugged everything back in the same way.