BMW To Customer: Aftermarket Parts Cause Fires, Airbag Deployments
Last month, I shared the story of an unexpected double front airbag deployment in a BMW X5. In the twenty days since then, that car’s owner has been working with BMW NA, which conducted an independent examination of the car while it was in dealership custody. Yesterday he heard from a BMW consumer service representative, who told him that BMW has determined the reason for the deployment.
If this was Upworthy, or if we used the Upworthy Generator to create headlines, we’d have to title the article “What This BMW Representative Told A Father About His Airbag Deployment Will Break Your Heart. The Worst Part Is At 4:23 In The Call Record.”
But seriously, if you have a BMW you might want to click the jump, because there’s a good chance that BMW’s reason for the deployment applies to you as well.
“You had an aftermarket battery that was not installed properly,” she tells him. “The positive cable had a loose nut. This caused thermal events… thermal damage to the cable. There were several faults stored prior to the deployment. The airbag light was on in your vehicle prior to the deployment.”
The owner states for the record that he never saw an airbag light and that, had he seen one, he’d have acted.
“The battery wasn’t installed correctly,” the rep states later on in the call, “which caused a short. The battery cable began to melt. There are two scenarios that could happen. Number one is your vehicle catches fire. Number two is there will be an airbag deployment. There was melted plastic throughout the cable.”
I try not to wear too thick of a tinfoil hat nowadays, so my first impulse is to believe that BMW did, in fact, discover a loose nut connected to a non-OEM battery in this X5. What’s confusing me is:
- Would a non-OEM battery with a tight nut also be a problem?
- Would an OEM battery with a loose nut also be a problem?
- Why would a loose nut cause the cable to melt?
- Why would a melted cable cause an airbag deployment?
It turns out that there are two battery cables on the positive side of a BMW airbag. One of them has an explosive charge mounted on it. Supposedly, when the airbags deploy, this device “blows the connection” between the battery and the rest of the car to protect first responders. You can see pictures of this device on E90Post.
So, it’s easy to see the intended chain of events there and not so easy to see how the charge cable might cause an airbag deployment. Perhaps we have a BMW tech in the B&B who can elaborate further. In the meantime, if you own a BMW that was manufactured some time in the past twenty years, you might want to consider having the battery, and cable, evaluated by your dealership. Loose battery terminals are as common in a parking lot full of old cars as empty cigarette cartons, so the news that having one could lead to an airbag deployment is worrisome, to say the least.
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Isn't this one of those BMWs where you have to go into the dealer and have the battery "blessed" by diagnostic tool? I'm so glad the only BMW I deal with is a 1970's motorcycle, whose only electronics are aftermarket parts.
My last BMW experience ('00 740iL) would confirm BMW's diagnosis. I bought the BMW used, with about 32k on it from a reputable Cadillac dealer in metro Atlanta. Clearly the previous owner had a phone and perhaps some other sort of two-way device mounted in the car as evidenced by the damaged console that the Cadillac dealer replaced. Apparently these devices were hard-wired to the trunk mounted battery which failed about a year after I bought the car. It was still under BMW's 4 year warranty but BMW refused to honor the warranty on the battery due to the non-standard wiring. Further, they cautioned that without me paying to replace the spliced factory trunk harness, further electrical issues would not be covered. I declined, took the car to a German independent who did concur that BMW wiring was hyper sensitive, installed a new battery for half what the dealer wanted and sent me on my way. 18 months of constant electrical problems (discharging battery, random warning lights, occasional gauge and radio malfunctions) I took the car back to BMW and paid to have the harness and battery replaced with factory parts. Outside of the BMW instrument pixels, the car never had another electrical glitch in 3+ more years of ownership. My experience with a VW years earlier was their electrical was less complicated but equally sensitive to American monkeying around. Eventually traded the 740 for a new Navigator and never looked back.