Handbook 652 Body Electrical Diagnosis Shielding Shielding is used on low voltage or low current wires such as those for the oxygen sensor, knock sensor, and distributor G and Ne signals. When a wire is shielded, an additional ground wire is wrapped around the insulation of the low current wire to absorb any electro-magnetic interference. In the EWD, shielding is represented by a dotted line around a wire. CAUTION When checking for voltage in a circuit that uses shielded wires, NEVER puncture the insulation with the test probe! This will short the sensor wire to the ground wire. Toyota does not recommend repair of shielded wires. To insure proper circuit protection, replace the wire harness.
Technical Training 71