This is a follow-up to a post that I made in the drivetrain forum.
In September, my 2007 CX-9 went through two BCMs (Body Control Module) in a month. The BCM controls the turn signals, door locks, dash warning lights and a lot more.
The root cause of the problem was a clogged sunroof drain. When the sunroof drain clogged, the water would overflow the holding area at the front of the sunroof, spill into the headliner and flow down the a-pillar covers. The BCM is conveniently located at the base of the driver side a-pillar, so the water would flow onto it and damage it.
As far as I can tell, there is no documented procedure for clearing the sunroof drains. I asked my dealer about it and they recommended spraying compressed air into the drain holes and making sure that lower drain holes (near the front mud flaps) are kept clear. On my car, there was no visible obstruction of the drains. It was only clear that a sunroof drain was blocked after putting water into the drains and looking for pooled water on the ground afterward.
If this happens to your car, unless you have a really nice dealer, you are on your own. I purchased the "TotalCare" extended warranty and, because it was "water damage", replacement of the BCM was not covered. I also contacted Mazda directly and got nowhere. This strikes me as odd because Volkswagen went through a class action lawsuit and big recall and repair reimbursement program because of a similar problem; you would figure that it would be less expensive to Mazda to get ahead of something like this.
I don't know the frequency of the problem. I have found reports of it from 2010. My dealer said that they had never had to replace a BCM in a CX-9 before and then had to replace two more while mine was in their shop awaiting the new part.
The symptoms of a BCM failure can be a number of strange behavior from the electrical systems. On my car, the first time, all of the warning lights on the dash were lit, and the turn signals and the power door locks did not work. The second time, the four-way hazard lights came on one day and would not turn off.
I wish that Mazda would do the right thing here and document a procedure for clearing the drains and including it as part of scheduled maintenance. I really wish that they would cover the replacement of the second BCM in my car.
alan
In September, my 2007 CX-9 went through two BCMs (Body Control Module) in a month. The BCM controls the turn signals, door locks, dash warning lights and a lot more.
The root cause of the problem was a clogged sunroof drain. When the sunroof drain clogged, the water would overflow the holding area at the front of the sunroof, spill into the headliner and flow down the a-pillar covers. The BCM is conveniently located at the base of the driver side a-pillar, so the water would flow onto it and damage it.
As far as I can tell, there is no documented procedure for clearing the sunroof drains. I asked my dealer about it and they recommended spraying compressed air into the drain holes and making sure that lower drain holes (near the front mud flaps) are kept clear. On my car, there was no visible obstruction of the drains. It was only clear that a sunroof drain was blocked after putting water into the drains and looking for pooled water on the ground afterward.
If this happens to your car, unless you have a really nice dealer, you are on your own. I purchased the "TotalCare" extended warranty and, because it was "water damage", replacement of the BCM was not covered. I also contacted Mazda directly and got nowhere. This strikes me as odd because Volkswagen went through a class action lawsuit and big recall and repair reimbursement program because of a similar problem; you would figure that it would be less expensive to Mazda to get ahead of something like this.
I don't know the frequency of the problem. I have found reports of it from 2010. My dealer said that they had never had to replace a BCM in a CX-9 before and then had to replace two more while mine was in their shop awaiting the new part.
The symptoms of a BCM failure can be a number of strange behavior from the electrical systems. On my car, the first time, all of the warning lights on the dash were lit, and the turn signals and the power door locks did not work. The second time, the four-way hazard lights came on one day and would not turn off.
I wish that Mazda would do the right thing here and document a procedure for clearing the drains and including it as part of scheduled maintenance. I really wish that they would cover the replacement of the second BCM in my car.
alan
