2002 Ford Marquis 4.6L Engine No Ground Signal on COPs - Fault Diagnosis
Hi everyone, I'm having an issue with my 2002 Ford Marquis LS equipped with a 4.6L engine. Coil #7 overheated and started smoking, which led to it failing completely. I replaced the coil, but the problem persists — coils 1, 2, and 3 are also not firing. I've confirmed that there is power signal to each coil, but no pulsing ground signal is detected. I've checked the PCM, ground connections, and wiring harnesses — everything appears intact. However, the lack of ground pulses suggests a deeper issue. Could this be due to an open circuit in the coil-to-PCM wiring? Is there a possibility of damage at the PCM connector or internal PCM failure? Any guidance on how to diagnose this further would be greatly appreciated. This is my first post here, so thank you for any advice!
Scan the vehicle for diagnostic trouble codes (DTCs), even if the check engine light is not illuminated. The absence of ground pulses from coils 1, 2, and 4 suggests a potential open circuit in the coil-to-PCM wiring or a damaged connector at the PCM. While PCM failure can occur, it's essential to verify all connections thoroughly before concluding that the PCM has failed.