I just replaced the motor in my 97 f150 (4.2 V6) and now I am having alternator problems. The alternator is brand new, tested good at the local parts store. My problem is, when installed on the truck, the output is roughly 11.5 volts, no matter the rpm's. I am pretty good with a multimeter, so give me some areas to check to find this problem. The battery is brand new also.

I need this truck running quickly but I would like to save money and fix it myself if possible. Thanks.