The 4LO light on my 2002 Quad Cab does not light when in 4LO. The truck does switch to 4LO. I suspect the bulb is bad. How do you get to it? Thanks

 

The bulb is not serviceable. It's also an LED with a dropping resistor. It shouldn't fail.

More likely it is a problem with the transfer case control module, tccm, or the harness.

You can test the "4wd low" LED. Disconnect the harness at the tccm and find the dark green with brown tracer wire from connector 1.

Connect the lead to ground and the LED should work.

The dark green with orange tracer is the "4wd high" indicator if you want to check that too.