If the switch does not light up, but the vehicle actually engages to four-wheel drive, then the issue is a bad switch.
If the light flashes and the vehicle does not engage 4x4 then the issue could be a faulty transfer case control module.
This can also be due to bad wiring.
Please let me know what you are experiencing.
I have attached diagrams for your reference.
Please let me know if you have any questions.
Images (Click to enlarge)
Monday, October 25th, 2021 AT 11:21 PM