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john aka eauto
john aka eauto, The Car Guy
Category: Mazda
Satisfied Customers: 15883
Experience:  ase tech,shop owner
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I have a 2012 Mazda CX9. I had the windshield replaced due

Customer Question

I have a 2012 Mazda CX9. I had the windshield replaced due to a crack. Roughly a week later it rained and I was inside my home. I heard the what sounded like my horn on my car going off....not like honk, honk, honk, but just an all out HOONNKK continuous. I ran outside and tried the remote to unlock/clear the alarm/horn, but it didn't work. I opened the hood to disconnect the battery (as the horn was blaring) and I could smell an electrical burning. I disconnected the battery and the sound stopped (Aghhh).The next day, I connected my battery but my key-less remote didn't work to unlock the car, so I had to use my physical key. When I turned the key there were a number of warning/indicator lights on (ABS, TCS OFF, ENGINE, BATTERY) and there was a high pitched buzzing (just like in this video https://www.youtube.com/watch?v=ulqXOTe--X8 ) coming from the engine compartment (near the transmission) but the car started just fine. However, my power door locks and rear power lift-gate didn't work. I read online that it was probably the BCM, so I found a similar one on ebay and purchased it. I disconnected the battery and held my foot on the brake for a minute to release any voltage.I installed the new BCM and my key-less remote worked, but when I went to start the car, every warning light on the dash was on. I went to turn the key and there was nothing. I noticed the KEY light was now red and figure that the immobilizer feature was probably on and would have to re-program my keys. I plugged into the OBDII port, but received the message that it couldn't communicate with the vehicle, so I can't pull any error codes or program the keys. I have checked all the fuses and they are good. I need some assistance as I really don't want to take it into the dealer, but I may be left with no choice.Summary of Problems:
-RED Key light on dash
-OBDII Port not working
-Car Won't Start (turn over)
-Buzzing Coming from Transmission AreaHELP!
Submitted: 1 year ago.
Category: Mazda
Expert:  john aka eauto replied 1 year ago.

Did you have the bcm flashed?

Customer: replied 1 year ago.
No I haven't.
Expert:  john aka eauto replied 1 year ago.

bcm will require programing from mazda in order to work properly in your vehicle

Customer: replied 1 year ago.
Okay, I wasn't sure if that was necessary as I've read of others online who have replaced their BCM's without "programming". Do they "program/flash" it through the OBDII port? If so, how can they if it's not able to communicate with the vehicle? Lastly do you have any idea what the buzzing sound might be?
Expert:  john aka eauto replied 1 year ago.

yes they do flash thru the obd port is the windshield leaking?

Customer: replied 1 year ago.
No it has been re-sealed and is dry.
Expert:  john aka eauto replied 1 year ago.

was anything wet?

Customer: replied 1 year ago.
I couldn't find anything wet other than a little water drip that ran down the A pillar. I've read that Mazda has an issue with sunroof drains clogging and allowing water to run down the A pillar and frying the bcm's, so that's what lead me to replace it.
Customer: replied 1 year ago.
But obviously something got wet to create this nightmare. ;-)
Expert:  john aka eauto replied 1 year ago.

fuse panels dry?

Customer: replied 1 year ago.
sir.
Expert:  john aka eauto replied 1 year ago.

and what happens when u plug in scan tool?

Customer: replied 1 year ago.
I receive a message "Tester not communicating with control unit".
Expert:  john aka eauto replied 1 year ago.

fuses good?

Customer: replied 1 year ago.
they seem to be. I tested them all with my power probe. I thought for sure something would have "popped"