Possible to short ECU out through diag. port??

[nitro_alltrac]

I've got a bad power issue with my 92 All Trac.

I've been having some interment electrical issues which appears to be a ground problem. It has happened a few times but not regular. What happens is that when I would turn on the signal light, hit the high beams or turn on the rear defroster (not together. Each occurence happened immediately after doing one of these) the rpms would drop dramatically for a few seconds and the check engine light would come on. I would turn off what ever I had done and give it more gas and the problem would go away. It had happened three times over the past few months. I had asked about this and the concensus was that it was probably a ground issue. Last Friday I had to stop on the way to work. When I came back out and started the car, same problem. I finally got it to stay running and got to work without issue. That evening, it did the same thing when I started it and had three or for incidents on the way home. The car started fine after I got home.

When I got home I decide to try and see if there were any codes stored. I followed the instructions in the BGB for pulling the codes by jumping the E and TE terminals in the diagnostic port. I didn't get anything. I also found that the body ground was loose, as was the negative battery terminal.

Now the big problem. I fixed both of these problems and when I went to start the car, nothing. The check engine light comes on and the battery light is on. There is no other power at all in the car. I checked the main fuseable link and it appeared to be blown so I replaced it. Still nothing.

On Saturday morning, I went out to see if I could track the problem down, but the car started! I drove it around for about 10 miles or so. No problem. Came back home and it started fine. I took it over to a friends garage and pulled the exhaust manifold off to put some inserts into the head for stripped manifold studs. Once everything was done, the car wouldn't start. Same thing as before.

I had some time Wednesday evening so I started checking things out from the battery. The fusible link checked out OK and I reconnected it to the main wire. I have power to the junction box next to battery, across all the big fuses in the front of the junction box, to the EFI 15A fuse and there is power at the connectors for the main engine relay.

I did some more checking today and found that there is also power going into the fuse block on the driver's kick panel and there is power at the ignition coil. By accident, I also found that if the key is in the OFF position, the horn will blow, the power door locks will work and the dome lights will work. Turn the key on and nothing.

My question now is could I have shorted the ECU out through the diagnostic port? If I did could it be causing the issues that I am having? This is driving me crazy. I need to try and fix this myself as first it is almost impossible to find anybody any good to work on an electrical issue and second it would cost a bloody fortune.

Any insight is greatly appreciated.