Page 8-96, 8-97 in the Electrical manual ...
PDF page 122
http://www.lilevo.com/mirage/89%20Colt% ... 0TURBO.pdf
There is a ground after the column switch for Low/High, and that will kill both headlamps output. Also, check the power in and out of the fuse 10A #6 and the headlight relay, likely underhood. Relay should have an open between two terminals and the other two should give you a resistance of like 70-80 ohms IIRC. If there is another identical relay nearby, or you have a spare, try swapping it in. If the relay fails, no power to either Low or High beam bulbs.