BSM Off Flashing

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CX9 Grand Touring
The BSM OFF light on the dash of our 2008 CX9 GT is flashing. Apparently it has been doing this for three weeks (wife's car) and was not tied to any event. Pushing the button has no effect.

I read the factory service manual and there are some voltage and continunity tests to run but I don't want to start tearing things apart just yet. Has anyone else encountered this issue? Anything I can check or reset before removing the bumber and tearing apart the back compartment to get at the sensors?

I did some google searches and have searched this forum but it doesn't sound like the issue is common.

Thanks,
brian
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
First I have heard of this. I've heard of the traction control light going crazy, but not bsm. Is there any damage on the rear bumper where you or your wife might have hit something?

First thing I would try is looking under the back bumper at the connections, if you can locate those sensors, try tapping them or unplugging them and plugging them back in. Maybe there is dirt in the connections? I don't even know where the sensors are but I presume they are in the general corners of the rear bumper.

Good luck!
 
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CX9 Grand Touring
No damage. Sensors are under the rear number on both sides at the corners not too far behind the rear wheels. Looks like i will be doing as you recommend. Hopefully a good cleaning is all that is required. If I can find my software disc I will hook up my obdII scanner check things out. Hopefully it will go away when i clear the codes and it won't come back.
Thanks
Brian
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
So interestingly, this just happened to me on a road trip. We stopped and gassed up after being on the road for hours. After getting back on the interstate, we realized there were a bunch of gnats in the car that we picked up at the gas station. Had the cruise on 72 and as soon as as i put the window down the bsm light started flashing. Put the window back up. stopped flashing after 30 seconds. Tried putting the window back down and same thing. The only wiring in the door for bsm is for the bsm bulb/amber light on the mirror. Makes no sense... We will see if anything else happens. I dont get how window down @72mph would trigger a bsm error.
 
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2017 Mazda CX-5 GT, 2016 Mazda6 iGT, 2014 Mazda3 sGT hatchback
helbigtw,
one possibility is the wire is shorting to ground when the window is down.
This is possible if the wire of BSM light is peeled off and rubbing against the frame.
i.e. flashing is triggered by volt=0, shorting to ground will do that also.

It happened to me before on my Prius when I installed signal mirror myself.
The wiring was not done properly. Over time, the plastic wrap of a wire got
peeled off from rubbing against the door frame.

Again, it is just a possibility. Pull the panel off, you can see if that is the case.
 
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CX9 Grand Touring
Interesting.... The only thing I've done to this car was to install the homelink mirror. Part of that involved splicing into the existing harness. The installation kit included splices which were pretty foolproof but you never know.... Any chance you installed a homelink mirror?

Still haven't found my SW for my USB OBDII scanner and have no chance finding it until my wife (and the CX9) get back into town. Still hoping a computer reset will clear the code.
Brian


So interestingly, this just happened to me on a road trip. We stopped and gassed up after being on the road for hours. After getting back on the interstate, we realized there were a bunch of gnats in the car that we picked up at the gas station. Had the cruise on 72 and as soon as as i put the window down the bsm light started flashing. Put the window back up. stopped flashing after 30 seconds. Tried putting the window back down and same thing. The only wiring in the door for bsm is for the bsm bulb/amber light on the mirror. Makes no sense... We will see if anything else happens. I dont get how window down @72mph would trigger a bsm error.
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
Nope, no homelink mirror. It only happened on the interstate while traveling @ 72mph when putting the window down. It won't happen at lower speeds when putting the window down. Very weird.
 
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2017 Mazda CX-5 GT, 2016 Mazda6 iGT, 2014 Mazda3 sGT hatchback
Nope, no homelink mirror. It only happened on the interstate while traveling @ 72mph when putting the window down. It won't happen at lower speeds when putting the window down. Very weird.
So it is even speed-related.... strange, indeed!
Which light did you mean exactly when you said "bsm light started flashing"?
The one on the mirror or the "BSM Off" light in the dash?
 
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'12 cx-9 gt
Thread revival!

My wife's 2012 gt (white if that matters) started doing this recently. Did you guys figure out a definitive conclusion? This thread did remind me that the car hasn't been washed in probably 6 months so I may do that soon.

Just to note, speed does not seem to be a factor since hers does it anywhere between 20 (when I believe the bsm system kicks in) to about 45 mph-ish. Our previous 2008 gt (black, again if that matters) never had this problem.
 
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CX9 Grand Touring
Thread revival!

My wife's 2012 gt (white if that matters) started doing this recently. Did you guys figure out a definitive conclusion? This thread did remind me that the car hasn't been washed in probably 6 months so I may do that soon.

Just to note, speed does not seem to be a factor since hers does it anywhere between 20 (when I believe the bsm system kicks in) to about 45 mph-ish. Our previous 2008 gt (black, again if that matters) never had this problem.
It ended up being a bad BSM module. There are two - one in each corner of the bumper. Cost $850 installed if memory serves me correctly. Since I find the option a nuisance I asked if they could disable it while keeping the blinking light off and the answer was no.

Apparently there is an easy way to test them and you can buy OEM replacements for ~$550.

I removed the rear bumper and tested for voltage on the harness and it worked as possible but I was not able to determine which BSM was bad because I didn't know how to test the radar module. My wife talked me out of trying to replace it myself so I bit the bullet and coughed up the $$$.

The tech said that this was the first time he had seen one go bad.

Brian



Brian
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
I've only had it act up once. I was on the interstate ~75mph and opened the window to toss an apple core and it started blinking. closed the window, and it stopped blinking after a couple minutes. opened the window again, and it started blinking again. I've never tried opening the window again ~75mph. But something triggers it when opening my window on the interstate for some reason. Other than that never had a problem on my 08 with 65k
 
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'12 cx-9 gt
Thanks for the feedbacks, I'll wash the car and see what happens first. If it acts up after that, i'll take it in before the warranty runs out.
 
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CX9 Grand Touring
I've only had it act up once. I was on the interstate ~75mph and opened the window to toss an apple core and it started blinking. closed the window, and it stopped blinking after a couple minutes. opened the window again, and it started blinking again. I've never tried opening the window again ~75mph. But something triggers it when opening my window on the interstate for some reason. Other than that never had a problem on my 08 with 65k

Interesting.... here's a theory for that one. I can't remember what the CX9 looks like under the rear bumper but most cars have a little vent with slats covered by pieces of rubber. The purpose of this vent it to have neutral cabin pressure so the air pumped in for heating and cooling can flow through to the rear.

I bet that when you opened your window a lot of air passed through that vent and somehow disrupted the BSM system since the modules on one side are near that vent.

Brian
 
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2009 Mazda CX-9 GT
Thanks for these posts (@all). Just bought a 2009 and have this same issue. Taking it in for some repairs (including this one) next week. Has anyone found a resolution less expensive than replacing the BSM module? That's a lot of loot to stop a blinking light... ;)

Thanks again!
 
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08 mazda cx9
I've always used a piece of duct tape to cover a blinking light. It eliminates it right away. Cost ya about .00000001! 😉 good luck. 😃
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
My bsm malfunctions if I open drivers window at 75mph , always has. It has malfunctioned once, maybe twice ever upon startup of vehicle. Turning car off then on again fixed it. Hasn't happened in years. Buy some parts on eBay or from a salvage yard.
 
I recently purchased a 2009 Mazda CX-9 GT with 175k miles. "BSM OFF" light on dash always starts flashing shortly after using the driver window switch. It stops flashing after a couple trips if window isn't used again. Doesn't matter if car is moving or not. I took off the door panel and saw that the door wiring harness is new, so I believe past owner tried to fix this already unsucessfully by replacing the door wiring harness. I recently replaced the battery and alternator, but that hasn't effected the problem. Blind spot monitoring works fine otherwise.
Any ideas?
 

helbigtw

T-Rav
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PA
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08 CX-9 GT FWD
You and I and maybe one other seem to be lone rangers with this issue. First time I ever discovered this was many years ago. Went to toss an apple core at 75mph and put driver window down and saw the flashing BSM and was perplexed. Never did figure it out. It went away couple minutes later) Also you might find that sometimes on warm days (over 70 degrees) it starts flashing. Might be getting old from muffler heat exposure. You should bought my 2008 that's going up for sale soon with only 103k.
 
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