A system includes a first controller including a processor and a memory, and the memory stores instructions executable by the processor to receive first acceleration data from an accelerometer; upon determining that the first acceleration data satisfies a first criterion, transmit a wake-up instruction to a second controller; upon determining that the first acceleration data fails to satisfy the first criterion, instruct the accelerometer to send second acceleration data; and upon determining that the second acceleration data satisfies a second criterion, transmit the wake-up instruction to the second controller. The first criterion includes jerk exceeding a jerk threshold.