4WD wiring on FJ62 Landcruiser

I'm starting to fix up a myriad of little things on the FJ62 I just bought this week. I'm looking at the 4WD light on the dash, but even after changing it, it still doesn't work, so I'm in fault finding mode. When I press the transfer switch, I can hear a relay click under the dash, but still no light. So either there's a break in the wiring to the light, or the 4WD system really isn't working. I presume the light is supposed to come on in both 4H and 4L modes. If so, then I presume the actuator is a switch somewhere on the transfer case rather than just having the light wired in parallel with the solenoid for 4H mode. Correct? I bought a Haynes manual but the wiring diagrams are pretty useless. Can anyone give me the inside info on the wiring to troubleshoot the light and, indeed, to see if the 4WD system is working at all?