ASP Pulley install--- charging issues now..

Recently did a TR224 swap. I also installed an ASP Underdrive pulley.

Car is having charging issues.
Voltage output only 12.8V at the battery using a fluke meter.

Disconnected the ground cable, car died immediately.

SES Light -- P1637 Generator L Circuit

I'm not sure if I have a bad alternator, or if I need to purchase the alternator pulley to go along with the ASP Pulley.

Has anyone else had this problem? Please chime in.

You could go get the alternator checked. If it's OK then either bump up your idle or go and get the alternator pulley.

This may seem like a dumb question but, did you install a shorter belt with the pulley?

I have an '01 with a TR230 cam and LT's. My idle is set at about 800. I have the March UD pulley and have no charging issues. Charges the same as before the pulley. The only time there was an issue was when my RPM would dip below 400RPM and then the lights would dim and that's about it. I didn't get the overdrive pulley for the alternator.