frank37

I drive a 2011 G37X Coupe.

On December 17th I unlocked the car with the button on the door with the key in my pocket. I entered the car and started it to warm it up while I cleaned off the snow. I locked the car with the button the door with the engine running and went back into my house to get something. When I returned, I pressed the button on the door to unlock the car and nothing happened. After a few tries, I removed the mechanical key and unlocked the door. When I sat in the car, the engine was running but all of the electronics were off. The car would also not shut off with the ignition button. I inserted the key fob into the dash slot and it still did not shut off. Very odd.

I was only able to shift the car into gear by pressing the shift lock button and the accelerator did not work. I immediately reparked the car. It was revving unpredictably without any input from me (max was about 1500 RPM). About 5 minutes later the car stalled. Even with the key fob in the dash, the car would not turn on, let alone start. I disconnected the negative terminal of the battery for 5 minutes and after reconnecting it and trying to start the car, it made the dead battery clicking noise. I successfully jump started the car and this particular issue has not since returned.

The issue: The buttons on the doors do not lock or unlock the car and the car will not start unless the key fob is in the dash (I have tried with both keys). The buttons on the key fob itself work perfectly. I have replaced the batteries on both of my keys. I have replaced the car battery (it was 5 years old anyways). I brought the car to Infiniti and had a 1 hour diagnostic done where they also reprogrammed the keys. They could not find an issue and stated that this would require an additional 2 hours of diagnostics after which the problem may still remain unresolved.

I read some things about the Body Control Module but don't really know where to go with this. Also, the Infiniti mechanic said that it was not the key fob antenna when I asked him, but I don't think this was specifically tested.

Does anyone have any thoughts as to what could be the cause of this problem and how it can be resolved? Please let me know if you need any more information.

frank37

I'm still having this issue. The car starts fine with the key in the dash but does not work if it is in my pocket.

Does anyone know how I can test the car's antenna which communicates with the key? Any other fixes?

Thanks for your help!

Elco

The antenna can't be tested individually using diagnostic software.
There is one antenna on each door handle, then there is an antenna in the trunk and 2 more antenna's inside the car.
Most likely the real problem is the BCM module.
Maybe the BCM module got some water damage.
It happen before on G37... water from the sunroof drain system leak on the right passenger side, exactly where the BCM is located, and cause problems.
Or it can be a leak from the rubber that watertight the cable passthrough from the engine bay IPDM into the cabin.

telcoman

Why are you so reluctant to spend an hour labor charge at your local Infiniti dealer to find the root cause?

If you can't afford that perhaps you should not be an Infiniti owner as you are over your head?

Just my $.02

Telcoman

frank37

Thanks Elco, I'll look into the BCM.

Telcoman, fair statement. I'm willing to spend the money if the problem will be fixed. I already brought the car to Infiniti and had the 1 hour diagnostic done and they didn't find any problems. The issue is that these types of problems quickly become money pits with no guarantee of a solution.

telcoman

Take it back
Only pay by credit card

Telcoman

frank37

Why only by credit card?

I'm becoming more and more convinced that it's the BCM after reading through some of the factory service manuals. Roughly how much does it cost to replace this?

telcoman

Because of the consumer protections that credit cards offer.

Telcoman

Elco

here: 10 11 INFINITI G37 OEM ATM ECU ECM BCM KEY FOB ENGINE COMPUTER G37X MEC109-010

Boomer-Bob

iTrader: (1)

Do you have a second key fob or key fob battery to try? I had to ask, it's a low cost easy diagnostic. :-)

frank37

Hi Boomer-Bob,

I replaced the batteries in both key fobs and tried them separately, no luck.

I suspect that the BCM is fried or hopefully a fuse is blown. I hope to have the opportunity to examine the fuses in the coming weeks and will repost if I find a solution.

frank37

A brief update:

The problem persists. I also noticed that the memory seat function does not work at all (the lights on the buttons don't even turn on). A fried BCM is the likely culprit.

I'll pick up a fuse test light tomorrow and start my diagnostics.

Will update if I am successful.

Does anyone know the rough all-in cost to replace the BCM (including all reprogramming)?

frank37

Cost is ~700 parts and labour. Getting it assessed tomorrow to confirm BCM is the culprit.

gueroRomo

Hey, its been a few years and having the same issue. Did you fix the issue and what ended up being the cause?

frank37

It never got resolved. I did not change the BCM as I didn't think the convenience improvement was worth 700 plus dollars for a possible but not guaranteed. fix. I no longer own the car.