The root cause can vary, but it often points to a problem with the PCM itself, its wiring harness, or a related control module. Things to investigate include:
* PCM internal failure: The PCM may be faulty and needs replacement.
* Wiring harness issues: Look for damaged, shorted, or corroded wires connected to the PCM. This is particularly important around the ignition switch and related circuits.
* Ground circuit problems: Poor grounding can prevent the PCM from receiving the correct signals to shut down.
* Other control modules: A malfunction in another module, such as the body control module (BCM), might be sending incorrect signals affecting PCM shutdown.
Diagnosis typically requires a professional scan tool: A simple code reader may only tell you the code; a more advanced scan tool can provide more detailed data to help pinpoint the source of the problem. A mechanic can use this information to track down the specific cause and perform necessary repairs.
It's crucial to address this issue promptly to prevent battery drain and potential further damage.
