Thanks for using JA.
The amber brake light comes on in connection with the abs light and doesn't not represent a fault.
The abs light on the other hand come on when the abs module detects a fault in the system and registers a fault code in its memory.
To find out what this code is the module has to be scanned and the fault diagnosed.
Most likely it's a fault wheel speed sensor,or a harness. some sensor may be attached to the hub and bearing assembly, so it's replaced as a unit.
I live in Alaska and the truck is always outside so is it possible that the sensor is just frozen and giving a false reading? Also if the ABS sensor/unit needs to be replaced does it need to be replaced right away or can it wait ... I just wanted to know if it is a safety issue if I do not replace it right away ..