I am bringing a wrecked ford car back to life. Had some wire harness damage but I believe I have it mostly repaired and did so before putting power back to the car.
In a nutshell, the 5V reference voltage for sensors is not right. A pile of codes having to do with low sensor voltages, low input, low output, etc. I tested at the throttle pedal plug, and then the pins right at the PCM for the throttle pedal and MAP. All are showing a consistent 2.1V. I tested voltage to the PCM using the PCM chassis as ground and the correct 12V power pins and see 12V at the PCM.
I know most of the manuals might immediately start pointing to a bad PCM but my gut is not there yet. The car will start and run smooth and nice for about 5sec, then start coughing and die. Being a car guy, I already know that means the PCM is sending good pulsing to the coils, injectors, picking up some sensors, etc. Most all PCMs also so a self check and there are no codes related to a PCM fault, only low voltage at sensors.
I am curious if this sounds like an overloaded 5V rail from a short at a sensor? I do not think I have a wiring issue but possible I suppose. I am trying to determine the easiest way to pin this down. I would think a total loss of 5V reference might point more towards a bad PCM? But 2.1V? It is trying!
Thoughts?
In a nutshell, the 5V reference voltage for sensors is not right. A pile of codes having to do with low sensor voltages, low input, low output, etc. I tested at the throttle pedal plug, and then the pins right at the PCM for the throttle pedal and MAP. All are showing a consistent 2.1V. I tested voltage to the PCM using the PCM chassis as ground and the correct 12V power pins and see 12V at the PCM.
I know most of the manuals might immediately start pointing to a bad PCM but my gut is not there yet. The car will start and run smooth and nice for about 5sec, then start coughing and die. Being a car guy, I already know that means the PCM is sending good pulsing to the coils, injectors, picking up some sensors, etc. Most all PCMs also so a self check and there are no codes related to a PCM fault, only low voltage at sensors.
I am curious if this sounds like an overloaded 5V rail from a short at a sensor? I do not think I have a wiring issue but possible I suppose. I am trying to determine the easiest way to pin this down. I would think a total loss of 5V reference might point more towards a bad PCM? But 2.1V? It is trying!
Thoughts?