I just thought I'd share some information that I have put together for my own use, and thought others may find it helpful. For reference, my car is a 94 Civic EX Coupe, manual transmission. See the attached excel spreadsheet. I made this by spending a lot of time testing continuity within the under-dash fuse box, by testing wires, and by referencing the FSM. This file is incomplete and may have some errors, and I'm not a wiring guru by any stretch of the imagination, so use at your own risk. Within the file, anything that is highlighted yellow, it means I didn’t dig in enough to find out the information. Anything that is highlighted orange means it’s a theory and I’m not sure if I’m right or not.

The first tab in the sheet (Harness Connections) shows all the connectors that plug into the under-dash fuse box. I also included screen shots of the fuse box diagrams from the FSM so that you can tell which connectors go where. On the figures I’ve numbered the pins according to what makes sense to me, and indicated what color the wire is at each pin location. The table below each connector lists out all the pins with the following info:

• Color: the wire color
• In/Out: Whether the wire carries power into (IN) or out of (OUT) the under-dash fuse box
• Source/Destination: Where the power is coming from (for IN) or where the power is going to (for OUT)
• Function: What the circuit is used for

The second tab in the sheet (Fuse Box) has a row for each fuse in the box, with the following information:

• Rating: The size fuse that is supposed to be in the slot
• In: Which side of the fuse the power comes in through
• Description: Where the power is coming from when it comes into the fuse box
• Harness: Which pin on which connector the power is coming from
• Color: What color wire is supplying the power into the fuse box
• Out: Which side of the fuse the power goes out of the fuse box from
• Description: Where the power goes to after leaving the fuse box
• Harness: Which pin on the connector the power is going to after the fuse
• Color: What color wire is carrying the power away from the fuse box

If you find it useful, cool. If not...oh well.

 

@Txdragon - here's what I said I would send you...maybe it will help?

 

Good start! I'm trying to trace the ground signal from the ECU to main relay.