Various electrical issues may develop related to the body control module (BCM). There have been reports of water damage to the BCM caused by clogged or damaged sunroof drains. It is recommend to periodically inspect the sun roof drain for debris and clean as necessary.Google+
Car Problem Reports
Mazda CX-9 Water Damage to Body Control Module
Mazda CX-9 Problem
Average Mileage: 48,685 mi (23,000 mi - 81,000 mi)
Visitor, 2007 Mazda CX-9, 28,000 mi
Water comes in through the windsheild and drips into the dashboard. It was poorly sealed but Mazda blames it on a car repair that was no where near the problem Now I have electical problems that they won't cover.
Visitor, 2008 Mazda CX-9, 32,000 mi
Alarm going off randomly, TCS lights, parking break light, oil light, BMS light, traction control, and interior lights with door ajar lights - all randomly going off and on while driving and/or holding still! Only happens on rainy days.
Mechanic did NOT find/fix this problem - he thought it was related to needing a new bearing (not). Fixed the bearing - still have all these problems. Now we are attacking the BCM ourselves.
Visitor, 2008 Mazda CX-9, 23,000 mi
Problem started when noticed my passenger side floor soaked, since I use the rubber floor mats I didn't notice this problem for some time. It was after a heavy rain that enough water came in and puddle of water was sitting on top of the mat. I had to use a wet vac. The dealership was useless in finding the problem. Since then after looking up the problem on the internet and seeing that it's an acurrance I've been cleaning out the ducts. Now I'm reading it can be a clogged a/c line is clogged. Enough said that now after have car in the shop getting ready for a long trip (just having fluids, etc being checked)the shop sees the parking lights on the next morning after a heavy rain. They discover more water in car and the module is wet, now I can't take care on the trip. they try to dry out the module. But after picking up the car the BSM, TCS, brake light and tc symble are all on. This car has nothing but problems since I got it new. And never once could the dealership find the problems that I had taken it in for. This car is well cared for and hardley driven to warrent these kinds of problems. I am at a lost at dishing out hundreds of dollars for repairs when the car is not abused.
Visitor, 2007 Mazda CX-9, 67,000 mi
The CX-9 showed a number of electrical issues (turn signals, door locks, other components did not work). Took it to the dealer who replaced the BCM. There were no signs of water damage. Four weeks later, after a heavy rainstorm, the BCM failed again (hazard lights would not turn off). The dealer determined that clogged sunroof drains caused water to leak onto the BCM.
Visitor, 2008 Mazda CX-9, 81,000 mi
Media button, blue tooth button don't work after rains and rear a/c fan blows on high for about 5 minutes after car is turned off. Also, low beam headlights alternate blowing at a rate of about one per month. Most recently, the rear wiper comes on and won't turn off.
Same thing. Dealership replaced in cabin air filter as though that would solve problem. Water comes in through windshield and now have an electrical problem that they will not cover under warranty. They are citing a minor accident where fog light was replaced as cause for windshield problem that has nothing to do with it. It is their way of getting out of repair.