A side-impact airbag defect has led to the recall of over a million GM vehicles, but not until after several years’ worth of investigation and documentation.

The defect in these side-impact airbags could cause them not to deploy when they’re supposed to.

The company says that corrosion or loose crimps in the wiring harness connectors for the side-impact airbags could cause increased resistance.

The airbag control system might sense that increased resistance as a problem and trigger the “Service Air Bag” warning light in the driver information center.

According to GM’s initial announcement, ignoring the “Service Air Bag” warning light may result in non-deployment of these side impact restraints. As time goes by, the defect can cause the resistance to increase to the point at which the airbags won’t deploy in a crash.

GM says the defect can cause non-deployment of all side-impact restraints, including the driver and passenger seat-mounted side air bags, the front center air bag, and the seat belt pretensioners.

How Long did GM Know About Side-Impact Airbag Defect?

GM finally issued the recall in March 2014. But company documents show the company reportedly knew about the side-impact airbag defect since 2008.

The company reportedly investigated the defect four separate times and issued six different service bulletins to dealers about this specific defect. GM also reported bought back an unknown number of vehicles because of the faulty side-impact restraints.

During a 2010 investigation, an engineer discovered that over 6,800 vehicles had been the subject of at least two warranty claims that arose out of a “Service Air Bag” message.

The company says that high number of claims was an indicator that its previous two service bulletins weren’t adequate to resolve the  side-impact airbag defect.

But a few months later, GM’s executive  committee in charge of issuing recalls decided to address the issue with just another bulletin and a special extension of warranty coverage. The company offered similar solutions in 2011 and 2012, but the warranty claims kept coming.

At first, GM wasn’t planning to issue a recall for the side-impact airbag defect. Instead, the company initially announced it would conduct a “customer-satisfaction campaign” – a less expensive way to address the problem that would not involve government regulators.

One day later, the company changed its tune. Within hours of informing the National Highway Safety Administration of its plans, GM amended its plan, implementing a full recall.

The company expanded the recall a few days after that to cover even more vehicles.

Vehicles Affected by the Recall

In its final form, the recall affects about 1.2 million GM vehicles from model years 2008 to 2013. According to the company’s announcement, the recall affects the following makes and models:

• Buick Enclave, model years 2008 to 2013
• GMC Acadia, model years 2008 to 2013
• Chevrolet Traverse, model years 2009 to 2013
• Saturn Outlook, model years 2008 to 2010

The repair would require GM dealers to remove the wiring harness connectors, then splice and solder the wires together, the company’s announcement says.