OK. Testing wires, I assume is done by checking continuity. Better way is to see the load is getting power. You know this, you just don't have a good map I suppose.

First up, is main power to the ECU. This arrives on the fat red wire fed by the blade fuse by the battery. It is responsible for getting power to the fuel pumps, the air mass meter, the idle motor, and the injectors -- all the power hungry stuff in the fuel injection independent of the ignition system. Because it carries a lot of current, the corrosion that creates faults in connections is not going to show up with ohmmeter checks -- you need to see it carry that current to a real load. Use voltage checks. A test light is fine.

There are two relays gating this power. One is called the system relay. It is there only because it can remain picked after key off for a short time to allow for the AMM cleaning cycle, but it feeds all those power hungry devices save the fuel pumps, which are gated by the other cube relay next to it. So the fat red wire winds up at terminal 30 on those two relays. A check of voltage there (while cranking) is proof the blade fuse circuit is working. An easier way is to backprobe the orange wire on the AMM which gets its juice through that system relay. Key on, it should be hot.

If all that is good, then you can begin to wonder about needing the harness opened up because the injector wiring is shorting out. But if that's the case, you're not looking to prove continuity, you're looking to prove the injectors see the ground provided by the transistor in the ECU for the short duration they need to be energized. A test light will do it. The 'noid light is just the $5 convenience for that function, as it comes with the connector that fits the injector.

As to what you might have bumped, a rotten harness is the #1 suspect. But at least be sure you have power.

The blue wire with the harness part number on it is the starter test socket. If you stick 12V there, you can crank from under the hood.

If you have another two-pin socket over by the exhaust side, that is possibly a clue you have either a replacement harness or the 84.9 version of LH2.0, which included a heated oxygen sensor. I would guess the former, or you would have mentioned it was plugged into a heated O2 sensor (HO2S). Wire colors go a long way toward identifying unknown terminations.


--
Art Benstein near Baltimore

The journey of a thousand miles begins with a broken fan belt and leaky tire.