Progress Thread Hoopty v2.0 - It All Snowballed

Noobz347 said:

Do these things have a habit of dropping dead on their own accord?

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Not that I've seen.

Apparently, there are internal fuses that will reset if tripped so either they arent resetting or the computer is just kaput. Ill still send it off

Well, some of you have followed my socials and saw that it hasn't been going well. Here's what I know:
- I have 12v at pins 1 and 37 on the ECM harness at the plug.
- swapped ECM relay, no change
- swapped the WOT relay and the fuel pump relay and no change
- swapped in a known good MS and no change
- The MS units will not power up and communicate with Tunerstudio

my gut is telling me bad grounds, but I'm not sure where to check for grounds on the main engine harness. I have the ol' TMoss diagram but it doesn't say where the grounds are located. I want to trace the black/white wires in the harness down because I cant think of any other things causing the issues.
Edit* I found some helpful info from @jrichker - thanks for the help buddy. Going to move some stuff around and see where that gest me.

Just a refresher, I took the car out a while back, the battery cable was loose (forgot to tighten) and it arced and the car went dark. Tightened cable and have no power to computer it seemed. Been chasing my tail since.

I feel like this is an incredibly simple solution, I just can't track it down and it's driving me nuts!

Update - I was able to jump the plug on the fuel pump relay from the red to light blue and the fuel pump kicked on.

Next, I'm going to try adding jumpers to the grounds and grounding the computer inside the car and see what that does.

Willybill32 said:

Is there any chance the arcing might have blown a fusible link?

Bill

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Ive been jacking around with it all morning - I finally unplugged the salt/pepper shakers and turned the key and it all powered up and the fuel pump came on. So, something in the engine harness is grounding out. Ill work on tracing that out next.

Alrighty.

What an absolute beating. The evap plug near the TPS was pinched between the FPR and the throttle cable bracket. It eventually ate through the insulation and was grounding the whole thing out. Never, ever would have guessed that, but its something I caused - nothing new there!

The bad news is the car runs like absolute hammered ass. Seems like I have a couple dead cylinders. Im going to put it all back together, let it cool off and then put some fresh plugs in it and see if that cures anything. I'm just happy it was a simple fix and didnt cost me anything other than a few less hairs on my head.

It was running rough because I didnt have the MAP line plugged in. All is right in the world again, I can focus on the Bronco.

The owner 3 people ago didnt sign the title right so I have to go through the bonded title process. Not looking forward to that - at all.
The motor has a bad wrist pin or a broken piston skirt. Other than that and a bad oil leak, it runs good.