Out-Of-Spec Ignition Switches: What’s The Deal?

Much fuss has been made with General Motors’ use of out-of-spec ignition switches, as the public has been scratching its collective head and wondering, “Why did GM use these if they didn’t pass muster?” According to Automotive News, this may not be an unusual circumstance.

“Just because a part is out of tolerance doesn’t mean that it’s the root cause of a failure. [But if the out-of-spec part] affects a component’s fit, form or function, that’s when you are expected to do a full root-cause analysis,” said Scott Gray, a senior program manager for the industry research consortium Automotive Industry Action Group.

Apparently, since 1993, there have been rules in place in using an out-of-spec part based on two documents: the Failure Mode Effects Analysis and the Production Part Approval Process. Both of these were developed by the Big Three:

• The Failure Mode Effects Analysis will show whether or not an out-of-spec part will work, or whether it might suffer a catastrophic failure. Engineers perform the analysis from the beginning of a component’s development. This is true for all components, so it can help engineers determine what happens with the use of an out-of-spec part.
• The Production Part Approval Process is the second stage, which involves the supplier producing the part to proper specifications. If there are any changes to the specs, no matter how minor, this approval process must be updated.

Hence, the smoking gun in General Motors’ case is the Failure Mode Effects Analysis, which should indicate whether GM knew about ignition switch issues. However, GM has yet to comment, other than spokesman Greg Martin saying, “We look forward to sharing findings, as appropriate, once completed. Until then, we will provide no preliminary comment.”