Hello!
The most likely causes of what you describe would be either a failed ignition module or a faulty powertrain control module. The ignition module receives a cranking RPM signal from the crank position sensor, which is used to determine when to fire the spark plugs. Since you have spark, the crank sensor and related wiring must be OK.
The ignition module also uses the crank sensor signal to calculate an RPM signal that is sent to the powertrain control module; the PCM uses this RPM reference signal to calculate when to fire the injectors.
You either have a faulty ignition module that is not generating a rpm reference signal for the PCM, a faulty PCM that is receiving a reference signal but not firing the plugs, or a fault in the electrical circuit in between the 2 modules.
By far the easiest way to determine which component is at fault is to connect a scan tool to the vehicle's data link to see if there is an RPM signal present at the PCM; if there is an RPM signal showing on the scan tool display then you have an internal PCM fault since it is obviously receiving RPM signal but not processing it correctly.
Alternatively, you can use a lab scope to monitor the RPM reference waveforms on circuits #400 and 401 to see if they are clean square wave digital signals.
I have posted for youb elow the portions of he control system schematics showing the connections between the 2 modules to help you locate teh circuits involved. I hope this is helpful; if so, please click my accept button and leave positive feedback! Thanks!
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