4x4 doesn't work on 1989 Toyota 4x4

I have a 1989 Toyota 4x4 V-6 and ever since I got it back from having a new cylinder head put on, the 4x4 doesn't work. The front drive shaft and axles lock in when I put it in 4H or 4L but the indicator light doesn't come on and the front tires don't spin (except for the free-wheeling action you get in 2 wheel drive.)