I posted this in the Haltech section but so far have had no replies, and a lot of these are most likely not exclusive to Haltech.

I'm swapping to an Elite 1500 and doing research on building the harness (which I've never done), so I have a few questions and will probably have more, if anyone can answer. This is on an FD btw.

I have a bit of a head start because I have a harness that Chris Ludwig built for my previous setup and I've been reverse engineering it to a degree, and I plan on using some of the parts that he made (sub-harnesses for the relay box, battery cables, possibly water injection pump relay, etc). I bought the flying lead harness for the ECU. I wish the wire quality was better, but I'm trying to save money a bit and it should serve its purpose for now. Maybe later I'll make another harness with better wiring and I'll use this one as a template. One reason I got the flying lead was because I don't have any experience building one and I figured it would help at least having the wiring correct for the ECU side. I've planned out for the most part which wires I need to add, which wires go to which connectors and which terminal in the connector they need to go to, etc.

1. In the harness Chris built, the crank angle sensor gets power from the EGI relay through X-05. Would it be OK if I tapped into that same power for the purge solenoid valve (for the EVAP system) and the IAC since that's where they get power in the stock harness, or should I just leave those for CAS? Or is the CAS wiring in the Haltech harness getting its power from somewhere else already? Also, does anyone know if it matters which wire goes where in the EVAP solenoid connector? In the wiring diagram, G/Y goes to 3H in the ECU connector and B/W comes from the EGI relay, but I'm not sure which wires goes to which side of the connector or if it matters. I'm adding this back in right now so I have nothing from before to reference.

I've since been told it doesn't matter which wire goes to which side of the purge solenoid connector.

2. Do I need to branch off the speed sensor wiring from the transmission to go to the ECU and also the stock connector? Or just to the ECU? I'm using a Speedhut GPS speedo so I wouldn't need a speed reference for the gauge.

3. I was told I need to run a wire to the power steering switch but I don't have a wire for that in the harness Chris built, and all that wiring goes through the other engine harness anyway (the battery/starter harness). Do I need to tap into the stock connector for that too? Is this a Haltech thing?

4. For the check engine light wire, I see it goes through connector B1-20 terminal K for the electrical load control unit. Would I just run the wire from the ECU into that terminal on the connector, or is there somewhere else I need to tap into?

5. Chris tapped into the SPA Techniques sensor wiring for the oil pressure sensor, but used only one of the three wires. I'm assuming it already gets power and ground through the gauge wiring and doesn't need power and ground through the ECU wiring. I'm going to need to tap into my fuel pressure sensor wiring the same way, although I've been thinking about replacing both sensors and building the harness for it with two outputs for each, one for the gauge and one for the ECU. Should I wire it the same way, with only one of them getting power and ground?

6. Chris built a separate harness for the water injection pump which contains a relay. I'm thinking about adding this to the relay box he installed instead of having it separate. I guess this isn't so much of a question other than asking for advice. I don't see why it wouldn't work. I was planning on just putting the sub-harness back in but if I can clean up the wiring a little more, I'd like to. I have a solenoid from Holley (just like the one I had with the FJO kit), I assume that doesn't need a relay since we didn't use one this last time. Then again, my water injection system only worked for about half an hour one day lol. We just couldn't figure out the issue.

There have been some new developments regarding WI since I typed up this post. I've been discussing with a friend that is also researching the topic and I'm now looking into getting a solenoid driver to pulse the solenoid (Low Amp Solenoid Driver : USRT, Usually Sideways Rally Team (usrallyteam.com), and running the pump off a relay, but I'm still not 100% this is correct. It kinda makes sense though, considering I'm somewhat mimicking my old FJO kit and it had a controller that pulsed the solenoid, and the WI solenoid circuit is what burned inside the Syvecs.

7. I wasn't planning on using a wire to the clutch switch but Chris' harness has one. I don't see a need for it though, but there's a lot I don't know about this subject lol.

So if anyone has any input on any of these topics, it would be appreciated.