Electical Problem??

The other day Went to start the truck. Once started the 4hi, 4lo & vsc light started flashing constantly. The ABS light was also on, but it wasn't flashing. Is this something major or just a sensor?
On another note does the 4.7 engine on the timing assembly have a belt or a chain? And if it's a belt, does it need be replaced once miles reach 90k?

 

Ended up taking truck to my mechanic. Turned out it was the wheel speed sensor harness for the left rear wheel. As far as the timing belt situation, I'm holding off right now. He's going to work up an estimate for the work to be done. Has anyone had this done and what damage money wise can I expect?

 

I broke my right side front speed sensor harness. Harness was approx $100 and took maybe 5 minutes to install. Not sure about the rear speed harness. Should be the same difference. I believe the 08 4.7L has a belt. Everything I found says replace at 90K.