Sometimes the starter won’t engage properly because not enough power can cycle through it due to a bad engine ground. Sometimes this results in weird ground “fixes” for sure, avoid the urge to add wires everywhere. In the above pic, you can see some of the weirdness that can happen with previous owner stuff. It had grounding wires everywhere and yet, it still had a starting problem. I fixed it by removing everything that wasn’t factory and replaced broken OE parts with new OE parts.
How to fix
There’s not a ton of components to this system. First you make sure the positive cable is solid and goes from the battery (+) to the starter solenoid (the tab with all the other wires on it). Also make sure the starter solenoid screws can actually hold it to the fender, sometimes you may need larger screws or create new holes.
The engine ground should go from the battery (-) to the timing cover on the engine, I suggest you buy this repo harness from LMR, it makes it easy and keeps the car factory.
Here’s how it’s connected to the engine, on the driver side front of the engine. Make sure to unbolt it, clean everything up with a wire brush, put it back together. The harness also connects to the computer ground and to the chassis. Make sure the chassis ground is good too (if the screw is loose, use another hole “giggity”).
Last piece to the puzzle is the chassis/engine ground strap. Bolted to the back of the driver side head and to the firewall. Make sure everything is clean and there’s a solid connection here too.
Keep it simple!
That’s all there is to it. The blue notch had all these strange bypass mechanisms where just fixing existing technology would have taken less time and be more dependable. The blue notch’s root problem was the bad battery terminal where the neg cable had a few strands left in it, plus it was all corroded. I removed all the surplus wiring, added new terminals and new positive cable replacing that weird connection that was made. It starts like a champ again.