The National Highway Traffic Safety Administration (TPMS) resolved certain technical issues on how the malfunction indicator light (MIL) is to flash when there is a problem. Under the original TPMS rule, when the MIL is combined with the low tire-pressure lamp into a single unit, it is to flash for 60–90 seconds followed by continuous illumination when there is a malfunction. The rule prohibits a second flashing in those instances during the same driving cycle where there are multiple, independent malfunctions.
However, this is problematic for vehicle designs that utilize "distributed logic" that allow the TPMS telltale to be independently commanded from different parts of the system. In response to a petition from the Alliance of Automobile Manufacturers, the NHTSA is changing the rule to allow, but not require, subsequent flash sequences when the initial malfunction is followed by others in the same ignition cycle.
For details, contact Stuart Gosswein at firstname.lastname@example.org.