Where is the signal relay on a 1998 Volvo S70 and how do you replace it?

The signal relay on a 1998 Volvo S70 is typically located in the fuse box, which is found under the dashboard on the driver's side. To replace it, first disconnect the negative battery terminal for safety, then locate the relay in the fuse box, pull it straight out, and insert the new relay into the same slot. Ensure the new relay clicks into place, and then reconnect the battery terminal. Test the signals to confirm proper operation.