Example embodiments relate to GNSS time synchronization in redundant systems. A redundant system configured with two subsystems may initially synchronize clocks from both subsystems to GNSS time from a GNSS receiver. The synchronization of the first subsystem's clock may involve using a first communication link that enables communication between the first subsystem and the GNSS receiver while the synchronization of the second subsystem's clock may involve using both the first communication link and a second communication link that enables communication between the subsystems. The redundant system may then synchronize the first subsystem's clock to the second subsystem's clock while the second subsystem's clock is still synchronized to GNSS time from the GNSS receiver based on timepulses traversing a pair of wires that connect the subsystems and the GNSS receiver.