How should information about aftermarket equipment wiring connected to the DLC be entered?

• A. Enter under 'Aftermarket Equipment Wiring' in the DLC notes.
• B. Mark as 'No fault' and proceed.
• C. The technician should fail the vehicle under 'Computer, Sensors, and Switches'.
• D. Document under 'Emissions Control' and continue.

Answer: (C)

Wiring added to the DLC can interfere with how the vehicle’s computer talks to its sensors and controllers. That interaction is part of the engine control computer, the sensors, and the switches that drive emissions-related systems. If aftermarket wiring affects diagnostic communications or sensor signals, the proper action is to classify and document the issue under the Computer, Sensors, and Switches category, noting a fault that prevents proper emissions diagnostics. This reflects that the problem lies in the computer/sensor subsystem, not simply in emissions output or in a generic aftermarket wiring note. Marking it as no fault would overlook a diagnostic interference, and labeling it under Emissions Control doesn’t address the root cause in the computer/sensor pathway.