ok so my engine grounds are just fine and its not my other tester. When I tested the voltage at the front I am only losing 0.1V between the front and back. I went to start the car and nothing....THEN the voltage at the front dropped down to 1V and it slowly climbed up to 4V.
I disconnected the positive feed to the starter and the voltage testing only the battery cable went back up to 12.6V. Then I held the 10 gauge red power wire which connects to the same post on the starter to the battery cable, tested the voltage and it dropped down to 6V, again, the voltage is still slowly climbing back up regardless of power to the system or not, its like my main system is acting like some kind of capacitor. I disconnected the alternator (1 wire alt) cable and no change so its not the alternator causing this.
I still think in the long run you should put a heavy gauge ground from your engine to the frame. Those two little grounds are fine for most stuff. But will probably get pretty hot when doing some heavy cranking to start the engine.. Also, they are fine for testing w/ a volt meter as very little current is being generated... I also wonder how the rest of your car is getting power?
The weird voltage readings seem to point to a bad power to ground loop. I don't know about the single wire alt. set ups. Since you diconnected your starter and ingition (coil, etc.), again, I would start there. If nothing else was changed or added, how could it not be somewhere there? Did you say you tried another (good) battery? Maybe this one is near it's end?
Ok for ****s n giggles, I tested the voltage between the battery cable and the 10 gauge wire to the alternator and harness, getting a full 12.6V where it should be 0.0V...I still don't know how the entire car is acting like a capacitor but now I know I'm getting a full ground from the fuse block ~somewhere~
It all matters how you have the power coming from the battery to the rest of your car. You are probaby measuring voltage across an open ignition switch at that point? Try measuring w/ the ignition in the run position. Wait, do the battery cable and 10g wire go to the same terminal on the starter?
Again, I really don't see how you are getting power to the rest of the car. I meant to say Junction Block, not box, if I said that. When the battery is in the engine compartment in it's tray, a wire (fusible link?) runs from the positive terminal of the battery to a little piece of plastic w/ a stud on it that is right behind the battery. From there, it is normally routed to the horn relay, voltage regulator (yours is now internal to the alt.), and alt. The power to the rest of the car continues on from there... I'm pretty sure the red wire on the starter solenoid just powers the solenoid.
OK, it's not so fun anymore...
I don't understand how it was fine before removing a few wires and now it's not! Either it's wire put back on correctly, bad grounds or connections, or the battery?.?.
I don't know, man. I feel like I'm guessing or making stuff up, now (second guessing myself)... Maybe I should stop "thinking out loud"...