89ltdcrownvic

I've got a buddy at work that actually has the 89 Crown Vic, He just rebuilt the 302 and put it back in. On the wiring harness that runs down to the tranny and the o2 sensor there is an orange wire that comes out of the harness where the firewall meets the floor pan and he doesn't know where to connect it because he doesn't remember disconnecting it and theres no obvious place for it to connect, but now the tranny won't shift from 2nd to 3rd (it did before pulling the motor). He had his Chilton manual at work and the wiring diagram shows it as a ground. Any suggestions?