Just got a 90 civic for my son. Turns over fine, but won't start. I took the igniter,coil,and main relay out, put them into an acura that I have and they all worked. Started looking around and noticed that the CEL comes on with the key but never goes off. The red light on the ECU never blinks, making me think its not getting power. The shift lock is also locked on the car, brake lights work fine, don't know if this is related. Thought possibly the ignition switch may be bad. Anyone have any info?

1. Check all under-hood and under-dash fuses with a test light or multimeter.
2. Clean the main ECM ground on the thermostat housing.
3. Perform the K-Test on the ECM. The CEL must go off on most Hondas, in order for them to start. Problem likely involves an under-dash fuse, ECM, ignition switch, or main relay. Based on your test of the main relay, I'd run the K-Test and focus on the ECM.
4. See if this helps:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-honda-civics-46563-3.html#post258005