A noid light connected across an injector's terminals remains on but does not blink. What does this indicate?

When a noid light connected across an injector's terminals remains on continuously without blinking, it indicates a problem with the injector driver circuit, specifically that the driver on the Powertrain Control Module (PCM) is shorted.

In this condition, the PCM is unable to turn the injector on and off as it normally would during the operation of the engine. Instead, the injector is receiving a constant voltage signal, which causes the noid light to stay lit constantly. This is a sign that the system is not functioning as intended, as injection events are typically signaled by a pulsing action corresponding to engine demands.

This situation suggests a fault within the PCM where the circuit controlling the injector is stuck in the 'on' position, failing to create the necessary modulation required for proper fuel delivery. Understanding this condition is essential for diagnosing fuel injector issues and ensuring that the fuel injection system operates correctly.