Which of the following is NOT a condition under which a PCM is considered unacceptable?

The correct answer identifies a condition that indicates a properly functioning Programmable Control Module (PCM). When all lamps are functioning correctly, it signifies that the module is operating as intended and meeting operational standards. This condition is essential for maintaining effective traffic control and ensuring that the signals convey the correct information to drivers and pedestrians.

In contrast, the other conditions listed describe scenarios where issues exist that can compromise the reliability and safety of traffic control devices. For example, having less than 90% of pixels operating means there are significant gaps in visibility, and lamps not dimming properly indicates a malfunction that could lead to impaired visibility during low light conditions. Additionally, having more than two lamps at different levels of intensity suggests inconsistency in signaling, which can confuse drivers and endanger safety on the road. Thus, recognizing that "All lamps functioning correctly" is not a condition of concern reinforces the standards required for traffic light systems.