I have a 1989 honda civic with a 1.5l engine, I sent the head to a machine shop and set everything right back up by Haynes book. (when I bought the car I didn't hear it run)I turned it and I don't have any spark or the fuel pump is not humming, when I look at the ECU LED light I see that it's blinking 20 times, I searched and found out that the code means ELD; I did a test I found in the internet where you have to check for volts on the ELD. I'm getting low voltage in a green/red .36 volts it sopose to be at least 4.5 volts, where I'm stuck is if to replace the ECU, test ECU or is this the test that tells me the ECU is bad? And why would this affect my fuel and spark?
Any answers will help thanks.

Erick

TXgreasemonkey will be here later I'm sure an has extensive troubleshooting on the Honda's in particular. And there is a stickey for it.
He may say change the ECU/ECM(whichever its called.
I would be sure of a good Battery to start with, low voltage on a battery may show lower than normal voltage elsewhere.
It controls all is why it can effect both. Fuel Pump may only have voltage a couple of seconds when ignition turned on.
https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563.html

Not a good problem to have. Perform the K-Test on the ECM. If it fails the test, install a remanufactured ECM or one from eBay--get an exact Honda Part No. match. If the problem persists, it may require replacing the ELD, which is only available by buying a new under hood fuse/relay box ($250)--try salvage. ELD problems are rare--my bet is the ECM is toast and it threw a bogus code.