Is my alternator bad or the pcm

Remove the alternator and have it bench tested. Some auto parts stores will do this for you. Hope that helps! Jim

Key on, check the field terminals for voltage. In the diagram, generator, the two wires on the right, are the field terminals. Both should be hot, use a test light. If both wires are hot, the generator field is ok. Check the generator bat terminal for voltage, on the left in diagram, use a test light, hot all the time, even w/o key. If no voltage, check fusible link or wiring circuit. You can use fused jumper wires for voltage and ground at generator field terminals, unplug the connector, that bypasses the pcm. By checking voltage at generator bat terminal, determine if it's charging. If so, I think the pcm is faulty. Always make sure wiring circuits themselves are ok. I happen to have a manual that talks about charging systems and possible testing, ford--gm--chrysler. good luck