Locate an Incoming Yellow Alarm
Problem
An incoming yellow alarm indicates that the T3 network element connected to the T3 interface has a problem with the signal it is receiving from the T3 interface.
Solution
To locate the yellow alarm, check the cable between the T3 interface and the directly connected T3 network element.
All diagnostics are from the perspective of Router 2. Figure 1 illustrates the location of a yellow alarm in a T3 network.
Figure 1: Location of a Yellow Alarm in a T3 Network

Meaning
The T3 multiplexer detects an LOS or LOF on its connection from Router 2 and sends a yellow (YLW) alarm to Router 2.