runningtoohot,
i think you actually won't see any symptom unless you move the harness (or if the harness has been moved) at which point the individual wiring insulation disintegrates. in my case my local indy was doing the head gasket, so of course he had to do something with the harness. the failure is this case was that the engine would just start stumbling when they touched the wires to the fuel injectors. they tried to chase it down by wrapping the exposed wires that they found before they realized how bad it all was. you won't see how bad it is because the wires are all within the harness. check out the wiring harness picture thread where the inside of a harness is shown.