The 4 lights were lit up on my 2005 BMW E53 X5 dash (tire, 4x4, brake, and abs). Lots of videos show the fix to be replacing a plastic gear on a transfer case actuator. My gear was fine but I finally tracked down a broken wire that monitors the front left wheel speed sensor.
FYI: I did some resistance and voltage checks on a good sensor and wire and here are the results... Resistance of the speed sensor (900k ohms)
Resistance of the two wires going to the control module (500k ohms)
Voltage of the wires going to the module with the key on (35-50 mV)