The 4wd light is activated by the vacuum shift motor in the front axle. Its a direct connection from the light to the fuse to the switch in the motor.
The brake light has a plug on it at the emergency brake. Check that switch and make sure your connection is clean. Get some electrical connector cleaner at Walmart and clean all connections.
Back to the 4x4 light. If this is not functioning your axle may not be locking in. This means your not actually getting 4x4. As the name indicates Vacuum shift motor, the axle is locked in using Vacuum. [Personally the vacuum system is crap and can be bypassed]
There is a write up on it here