It's a 12V solenoid so the wires don't need to be shielded. Shielding is really only important on sensor signal wires, which are usually 5v (TPS, MAF, etc) or 1v (O2 sensor) extremely low amperage circuits which are far more sensitive to slight voltage fluctuations and interference.

+1! And good find! I have several wires broken inside the insulation that have eluded me. Can't remember seeing one on an older vehicle though. Bravo!

My congradulations also on finding the elusive trouble. It had to be with the wiring or the device itself. I assume the problem is due to a broken wire inside the wire insulation and not the pin connecting the wire to the ECU. You can just splice the bad spot and even if you have to cut back some of the shielding that won't be a problem. Usually the shields come together at a common spot and are bonded to ground.