The relation may also arise where antecedent and consequent are two effects of a third cause. In such a case the antecedent need not itself cause the consequent; both may be tied to the same underlying cause.
Imagine a specified alarm system in which one malfunction both illuminates a warning lamp and triggers an alarm. The two effects share a cause; the light does not necessarily cause the alarm.
This is an explanatory illustration. A common cause does not make every pair of its effects invariably simultaneous; the relevant conditions of the particular system matter.