89 Iroc 350 TPI, cooling fans don't turn on. Fan switch is new, if I unplug connector from fan switch and ground it with ignition on the pass side fan will run. If I ground it with the engine running both fans will run. Is there anything else it could be besides a defective fan switch/poor ground to switch? Does the CTS/PCM control fan function at all or is it just controlled by the fan switch?

The ECM controls one fan and the A/C and the overheat switch control the other fan.
If you let the car heat up to 230+ degrees, the ECM should kick in the primary fan.
If the first one doesn't kick in, the overheat switch in the passenger head should kick in shortly after and turn on the secondary fan.
The A/C should make both fans turn on.

If you find out that one fan is dead, maybe this troubleshooting article might be of use: http://www.austinthirdgen.org/index.php?pid=36

Hope this helps.
Lou