2004 Chevy Silverado 1500 Crank/No Spark Conditions

2004 Chevy Silverado 1500 RWD 5.3L V8 with 286,000 miles.

Problem Statement: I am having issues starting the truck and it stalling out or not starting at all. Sometimes, it will crank but the engine won't turn. Other times, I am able to get the engine to turn over but it will stall. Other times, I don't even get a crank. Other times, it starts right up. Once started, there aren't any issues. I am also getting an intermittent C0298 which is a 'Requested Torque Singal Circuit'. There seem to be many causes for this, one of which is loss of ignition timing. This, paired with intermittent spark (see below) leads me to think the CKP/PCM is the issue.

Other codes present:
B2610: Passenger compartment dimming #1 (cluster, etc.) circuit malfunction
B2615: Passenger compartment dimming #2 (dome lamp, etc.) circuit malfunction
--I replaced all interior lights with LEDs so that may be the cause

Digital Radio Receiver Codes: (I replaced the stereo a while back and have had this present since then)
U1301/1000: Class 2 Data Link High/Malfunction

B0229: Recirculating Door Overtravel (HVAC)

Background details:
Issues started around 6 months ago when I had to replace my starter (I'll come back to that in a minute). Since then, I've had issues starting the truck. Unfortunately, I've been firing the parts cannon trying to fix the issues. I thought it was the ignition switch so I changed it but the issue persists. I had the alternator and battery under warranty so had both replaced. I then repaired all engine/PCM grounds thinking that may be the issue. A few weeks ago, the fuel level sensor went out (P0461 and P0463) so I ended up replacing the entire fuel pump this last weekend. It was probably on its last legs anyway as it was idling around 50 psi (GM spec is 55-62). I checked the idling PSI last night and was at 56-58 so I don't think fuel is the issue.

I had a mechanic neighbor connect a noid light a few weeks ago when I was having issues starting the car and there was no spark. This led me to think the CKP sensor must be the issue. I have a BlueDriver OBD2 reader and can read RPMs so I would think the CKP and CMP are working correctly. The CKP sensor sits directly above the starter (see above) so I was certain I must have damaged the wires somehow when I replaced it. I removed the starter and checked voltage at the sensor and the starter for comparison. The CKP power wire was .8V lower than the starter. I checked at various points along the wire and the voltage was consistently .8V lower.

This led me to think the PCM/CKP  was somehow the issue. I removed the PCM from the vehicle and there was a fair bit of corrosion around the 12V reference single wire for the CKP (Pin 2 BLUE connector). I installed it back on the vehicle and backprobed Pin 2 and was still getting .8V lower than battery positive. I checked all battery supply voltages to the PCM and all were .8V higher than Pin 2.

See pin-out here . LT GN Power wire is Pin 2, GND is Pin 21, and Signal is Pin 12. I verified I have a good GND on that wire and I am getting voltage on the Signal wire (also getting RPMs on the dash and the OBD2 reader).

See the wiring schematic here .

My thinking now is there may be something wrong with the PCM itself? Is it reasonable to assume there may be some broken resistors along the trace for the CKP power voltage and this is causing the voltage drop? I've never removed the CKP sensor, but maybe I need to do a relearn procedure.

Thanks in advance for any help you can provide. I apologize for how disorganized this thread is, I am trying to make sure I am including all relevant information.

 

I want to clear up some terms here.
Crank: the starter motor is engaged and the engine is turning.
Turning Over: the exact same scenario.
Firing: ignition taking place. Wether the engine runs or not, burning of the fuel is firing.
That said, does the truck ever NOT CRANK?
If yes, forget about crank and cam sensors. They have nothing to do with the starter motor TURNING OVER the engine.
If it always TURNS OVER, but does not FIRE, or FIRES and stalls, then that is a different symptom.

Thanks for your response. Yes, there are times where nothing cranks. I understand your point about the CKP having nothing to do with the starter turning over the engine.

That being said, what should I be looking at next? PCM?

Should I be considering this a no crank/ no start and diagnose from there?

yes you say it stated when that was changed , why . did you have the old one checked ? maybe a starter cable or wire to ingnition short or battery with weak cells . check that good luck

I removed the PCM from the vehicle and there was a fair bit of corrosion around the 12V reference single wire for the CKP (Pin 2 BLUE connector).

Corrosion in the PCM connector is never good news obviously. It could potentially explain all of the symptoms you are experiencing, depending on how severe it is.

Issues started around 6 months ago when I had to replace my starter (I'll come back to that in a minute)

This makes me suspect they there may be two problems at play. I don't doubt that it needed a starter (especially at that mileage), and respectfully, I don't intend to doubt your skills, but it's been touched. To the unobjective observer, it must be considered that there could possibly be a starter installation issue causing the intermittent no crank, and another issue causing the intermittent crank/no start/ stall.

I think I would probably start by observing PIDs related to anti theft like run, fuel & start enable/disable. Input-Output pids like ignition switch state, crank request, starter relay command state, fuel pump command.

Should I be considering this a no crank/ no start and diagnose from there?

I would only while it's not cranking, otherwise I'd want to know what's going missing when it's cranking but not running. A quick squirt of brake clean or starting fluid in the intake while cranking would help determine if it's fuel or spark related.

Have a safe and happy New Year!