I have a 91crx si and the main harness was a mess when I got it recently I was cutting wires i didn’t need anymore like the heater motor etc now the ecu doesn’t seem to be getting power I’ve checked all the grounds I know of a m not sure which wire feeds the ecu power

 

Do you have a copy of the factory service manual (FSM)? They can easily be found online by googling around. There are good wiring diagrams in the FSM. Get a copy and get out your multi-meter. Happy hunting.

 

power for the ECU comes from the Main Relay

 

I have a new relay that I keep switching between I was trying to find the tps wire when I moved the harness close to the ecu it would flicker. I have the wrap completely off the harness and don’t see any broken wires

 

It could be a worn out harness terminal that isn't making good connection with the ECU pins.

 

I bought a cheap adapter off eBay I was kinda thot that may be it I don’t understand the manual very well I can’t tell which wires directly affect the ecu power

 

Is there anyway to check if a ecu is bad by looking at it. Like if it’s not burnt or the the lines are still in contact it should be good rite

 

Does anyone know if a civic main harness would work

 

This is driving me crazy all wires that should be hot have 12 volts on plug a. All grounds are grounded on plug a there shouldn’t be any other wires that would keep it from working

 

I assume you're checking the pins in the connector with the ECU disconnected? To test my theory of having worn out harness terminals, you can remove the ECU cover, plug the connectors in, then CAREFULLY probe the back of the pin inside the ECU. If the wire in the plug has power when disconnected from the ECU but you're not getting it on the pin inside the ECU, the terminal in the plug is worn out and not making contact with the ECU pin.

 

(2) yellow with black stripe wires from main relay to ECU at pins A13 and A15

 

No luck I got 12v on both pins in the ecu can a ecu be bad without showing any Visible signs

 

The s300 says the ignition is off even though I know it’s on I hear the injectors click and the main relay clicks

 

It is possible for the ECU to be bad with no visible signs. However, if I understand correctly that it was running fine before you started cutting out wires, it's unlikely that the ECU would be the problem. Do you have a spare ECU you can try in the car, or do you have another car you could try the ECU in?

 

I wish I did unfortunately I’m going to have buy one just to see if that’s the problem if that doesn’t work I’ll just buy another harness