Haltech Nexus R3 Brownout/Blackout

I have just finished wiring my DF Goblin kit car with a Haltech Nexus R3 and I am getting a brownout issue when I crank the car. Originally I had HCO 3 running to the starter motor solenoid but I kept getting an overcurrent issue so I wired in one of my relays in the fuse box to the starter solenoid and I am triggering it with a HBO. Whenever I crank the vehicle the dash will usually restart but the vehicle will keep cranking. I didn't think it was much of an issue until I went to do the timing with the timing light and there is no current going through the trigger wire for cylinder one coil pack. I am getting overcurrent's for all 4 HCO which are codes P1946, 47, 48, and 49. I still get these overcurrent warnings even if I disconnect the output wires. When the dash does stay on it hovers around 10.4V on the battery, do I maybe need some kind of capacitor so that it can make up for too large of a voltage drop?

The wiring for my main power wire is drawn out in LTspice below. The main ground triangles all go to chassis ground and the battery master kill switch is this. (I am not the best at doing these drawings)

Any help would be much appreciated!

You need to do a voltage drop test across every connection between the battery and the starter (both positive and negative sides). You can determine where the voltage drops are occurring, and replace a wire, connection or component. It could easily be a Master Switch, Crimp on cable, Solenoid or even the Starter Motor.

You might just need larger gauge wire going to the starter solenoid. Starter Solenoids can pull 40 amps or more for the first tens of milliseconds.

Ok so I was finally able to get back to the car again and did some resistance measurements. The only one that came up above about an ohm was from post to post on the master kill switch. The resistance when it was just on was a normal 1 ohm but then under cranking it would jump all the way up to 137 ohms and then fall back down to around 65 ohms. I think there is some voltage sag so I ended up replacing the battery and now I am not getting brown outs but it is still throwing the overcurrent codes. I got on with Haltech technical support (those guys are great!) and we went through some trouble shooting, nothing seemed to work but the guy I was talking too said that the R3 is super voltage sensitive and that I need to separate circuits. This didn't make full sense to me as I already basically thought in theory the two will be in parallel no matter where the node is for where they separate (eg. the battery, kill switch post, or starter motor power lug). So I am going to try this by separating them by running two main 4 gauge wires off of my battery, one that goes to the kill switch, the other will go direct to the R3. Should I also be running a separate ground wire for the R3 that goes straight back to the battery as well instead of grounding it to the chassis?

If someone could give me the technical explanation for why moving the start of both circuits to the battery that would be great because in my mind they will work the exact same way.

If this doesn't work I am thinking that the voltage is sagging too much for the R3 to keep up with so maybe adding a capacitor in the R3 circuit would be a decent option.

I was finally able to get the car working after installing a BUS bar coming off of the battery. My main 4 gauge battery circuit goes from the battery to the bus bar and one connection goes directly to the kill switch which controls the R3's on and off wires as well as the starter motor power. The other connection goes directly to the R3. I still don't fully understand the physics behind the issue of running the starter and R3 in parallel. I did some research and it's possible it is from reflection at the node which could cause some odd voltage behavior that freaks out the R3. It is also possible my kill switch was causing some noise in the circuit somehow which affected the R3. Still a lot more to get figured out but I will mark this down as resolved.