alternator problem

[sausagedoc1982]

Hi guys

Having bother with my van. Is a 2000 model with a DW8 engine. The battery light wasnt light on the dash so I thought it was the alternator. Changed it but still the same. I tested for power at the small wire and I dont have 12volts at this wire. Ive tested the fuse and everything is good. The problem is that I dont know were to go from here. I dont have a wiring diagram to trace wiring. Can anyone help me on were the wire runs to and from the alternator and were to go to next.

any help would be great
thanks