93 GL ATX Distributor Troubleshooting

[DetroitDon]

I've still got an ignition problem with my 93 GL ATX. No ignition spark. Is there any way to troubleshoot the distributor? The Haines manual suggests checking the two leads on the distributor, but the 89-93's have a plug with 4 wires. Any ideas besides replacing the entire assembly? This ignition trouble has me REALLY stumped. The Haines manual procedure to test the ignite also makes no sense.

PLEASE HELP!!! Getting desperate!

Don