CX-9 Body Control Module (BCM) failure

Fun2Fly.Cincy

Former CX-9 Owner
:
CX-9
Hello
I purchased my 2008 CX-9 Touring in July of 2008.
In August I installed an aftermarket trailer hitch and a plug-in Draw-tite wiring kit. It all worked fine. In October I accidentally left the moon roof open over night and the interior was rained on rather heavily. When I started the car up to move it indoors to dry out I noticed an electrical burning odor and some things stopped working. I found the fuse for the turn signals blown. I replaced it and it did not blow again. I took it to the dealer and they instantly said my trailer wiring was at fault and no warranty applied. They did not test anything. They just assumed. I chose to fix this myself. I bought the manuals from Mazda. I quickly found that the Body Control Module (BCM) is not functioning. This kills the turn signals, door locks and interior overhead lights among other things. I also have a few incorrect lights on the dash. I checked the turn signal wiring and it is not shorted with or without the trailer wiring plugged in. I am an automation engineer and I wire things for a living. I checked the turn signal circuit by putting voltage on the output of the BCM and they seem to function fine with and without the trailer wiring plugged in.
I hesitate to plug in a new BCM since I haven't yet been able to determine what killed the old one. I assume it had something to do with the water.
Any similar experiences or suggestions?
Thanks.....Frank
 

go0phi

2008 Mazda CX-9 GT
:
Mazda CX-9 2008
Frank,

Where did you buy the CX-9 manuals from?

I would assume these include the wiring diagrams and information on the buses connecting to the BCM, etc.

Thanks.
 

OMF

:
2007 CX-9 GT AWD
2007 CX-9 BCM Inspection (Set #1)

Just in case you want to inspect your BCM...

Note: this is 2007 model year!
 

Attachments

  • 2007 CX-9 BCM INSPECTION 1 of 10.pdf
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  • 2007 CX-9 BCM INSPECTION 3 of 10.pdf
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  • 2007 CX-9 BCM INSPECTION 4 of 10.pdf
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  • 2007 CX-9 BCM INSPECTION 5 of 10.pdf
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OMF

:
2007 CX-9 GT AWD
2007 CX-9 BCM Inspection (Set #2)

Set #2

Good luck!
 

Attachments

  • 2007 CX-9 BCM INSPECTION 6 of 10.pdf
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  • 2007 CX-9 BCM INSPECTION 7 of 10.pdf
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  • 2007 CX-9 BCM INSPECTION 10 of 10.pdf
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2012 CX-9 Touring
Reviving this from the zombie dead.

Thanks. The docs helped with a swap after the sunroof draines showered the BCM.

My replacement was an eBay part and one plugged in we checked all we could.

All the button beeps returned, need to figure out how to disable that.

All in all of this fixes the sticky parking light problem I'll be very happy
 
:
CX-9 2013 AWD
Reviving this from the zombie dead.

Thanks. The docs helped with a swap after the sunroof draines showered the BCM.

My replacement was an eBay part and one plugged in we checked all we could.

All the button beeps returned, need to figure out how to disable that.

All in all of this fixes the sticky parking light problem I'll be very happy

glad it worked out for you, how did the sunroof drains soak the BCM ? I keep hearing of this issue but can't see how this happens if the sunroof is closed , does it only happen to owners who leaves their sunroofs open on nice days and tree leaves clog the drain and the rain water just starts collecting and soaks the BCM ?
 
:
2012 CX-9 Touring
glad it worked out for you, how did the sunroof drains soak the BCM ? I keep hearing of this issue but can't see how this happens if the sunroof is closed , does it only happen to owners who leaves their sunroofs open on nice days and tree leaves clog the drain and the rain water just starts collecting and soaks the BCM ?
The drains don't.

This car is parked outside on a tree lined street. My understanding is the dirt clogs the drain lines. A blast of compresses air helps keep them clean.

Also I understand the sunroof seals are not watertight but water resistant so in heavy rain water gets into the drain areas.

So the drain gets clogged. The water weeps around the connection and down the outside of the hoses to then get the footwells wet and the driver side kick wall wet. That's where all BCM connections in the car live.

Water plus electronics and the gremlins move in.
 
:
Mazda
Just replaced my bcm on my 2012 Mazda CX-9.
Everything is back to normal. It took about one hour to carefully remove connectors with flat screwdriver and there was 2 screws holding bcm to car body.
I paid for bcm $382+tax at Mazda parts in Wayne NJ.
 
:
Mazda CX-9
I need my 2007 CX-9 BCM replaced. If I get one and replace it on my own, does it require any programming or anything? Trying to save $400 if possible.
 
:
2012 CX-9 Touring
Ok thank you for the reply! Do you have a key fob with the keyless entry? Just worried that I swap mine out for like $300 myself and find that my wife can't unlock the car with her fob.
Yep 2012 Touring. Key pairing is not part of BCM.

You need to turn off the dashboard control feedback beeps (well I did, they drive me crazy) but that's about it.
 
:
Mazda CX-9
Last bit here. The part numbers vary a bit. The price difference is about 50-60. The cheaper one has anti-theft with alarm and the other does not. Any tips on what I should get? Dealer part number is the one without and is more expensive but based on what I can find I can use either one.
 
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2012 CX-9 Touring
Last bit here. The part numbers vary a bit. The price difference is about 50-60. The cheaper one has anti-theft with alarm and the other does not. Any tips on what I should get? Dealer part number is the one without and is more expensive but based on what I can find I can use either one.
You get the part number thar corresponds with the part you are swapping out.

You can pull the trim panel off the driver side footwell to confirm the part number.

Try to match part number and model year.