Question

A vehicle came in with a left tail light out.

Replacement of the bulb did not fix the problem
An incandescent test light illuminates when probing the power side of the bulb socket

Technician A says there must be a blown 15A Tail/Park circuit fuse
Technician B says there may be a fault in the ground circuit

Who is correct?

Answer 1

Technician B is correct because a functioning power side and a non-illuminating bulb point to a possible fault in the ground circuit, not a blown fuse.

Step-by-step explanation:

Technician A suggests that the issue is a blown 15A Tail/Park circuit fuse. However, given that the incandescent test light illuminates when probing the power side of the bulb socket, this indicates that power is indeed reaching the socket, thereby negating the likelihood of a blown fuse as the primary issue. Technician B posits that there may be a fault in the ground circuit. This seems more likely because if the power side is functional as indicated by the test light, the ground connection may be the problem, preventing the circuit from completing and the tail light from functioning. For the bulb to illuminate, there needs to be a complete circuit which includes an intact ground path.