GM’s ignition switch saga: less than meets the eye

Recalls, once rare, are now so frequent that they barely warrant mention in the daily news. Of the recent batch, the mother of them all is the General Motors ignition switch problem. So far, 13 deaths in the US are attributed to it, caused by a simple issue: the key rotates back to the “off” position, shutting down the engine and power steering, as well as the air bags. It should be noted that the effect is the same as stalling the engine while in motion … steering control is not lost, but the lack of power assist makes it more difficult.

Similarly, the media don’t understand that the check valve and vacuum operation of power brakes give enough boost and long enough to bring the car to a safe stop. Ironically, power steering has become standard on almost all modern cars and light trucks, despite lighter weight combined with the almost universal adoption of rack-and-pinion systems which make modern cars significantly easier to steer when power assist is lost compared to the behemoths of a generation ago. Tragic as the fatalities are, the defect is not as serious as the mass media would have us believe.

Part suppliers to the OEMs either build the part to the customer’s drawing or design the part to the customer’s specification, but either way running changes to improve reliability, reduce cost (or both) are common. In the case of the GM ignition switch, reports of the keys turning back resulted in a running change to the design, one which was not accompanied by a change in the part number. This means that it’s difficult to impossible to determine which switches are bad, and hence a massive recall. The mass media are reporting this as if it’s a criminal conspiracy.

The fact is running changes are commonly tracked by the print revision numbering system, not by part number. Changing part numbers with each print revision would cause supply chain chaos, adding to confusion that already exists when new parts carry numbers that supersede older designs. The move to standardize common parts across multiple models is not only a unit cost control measure, it is also intended to control part number proliferation.

That’s a good thing. But if OEM customer feedback results in a demand for changes that significantly alter the part’s form, fit or function, the customer will ask for and get a new part number. Changing to an internal spring with a slightly higher tension wouldn’t justify a new part number since the problem was a convenience issue, not a safety problem when it was first noticed.

But this is nothing new; it is continuous product improvement. Has the recall hurt GM? GM sales remain strong and other manufacturers are cleaning house with recalls of their own. With the desire to increase parts commonality across multiple models, larger recalls can be expected. No one in the industry wants to make bad products and in my experience with suppliers to the OEMs, cost cutting hasn’t come at the expense of safety since the 70s. Toyota bounced back nicely from their accelerator pedal issue, and GM will do the same.