2016 ram 1500 5.7 crank no start, bad crank signal.

Hello. New to the community and new to the forum (well any forum in fact). Hopefully I'm posting this in the correct place and looking for some guidance! I currently have a 2016 Ram 1500 5.7 in my shop with a crank no start condition. It has no codes and good fuel pressure. Started with a relative compression, results are good across all cylinders. I decided to move to a crank and cam waveform to see if I may be missing something there. What I'm finding is that my crank signal was stuck at 5v and at times would drop to ground while cranking. Not a good waveform at all. So I checked my ground and reference from PCM and they were good. Made sure I also wasn't loosing it while cranking. Viewed my reluctor wheel with a bore scope while turning the engine by hand and found no issues there. At that point I made the call on a crank sensor. Replaced the crank sensor and cleaned the block very well where the sensor mates. No change in results, still no codes. Used a Mopar sensor. Began looking at the circuit a little more in depth and did some testing at both C2 PCM connector and crank sensor connector. I have no change in this signal throughout the signal wire to PCM. Viewed some live data while cranking and I can see after a few seconds of cranking, my crank and cam sync pids are "in sync" and the tach does read a little RPM change, still no codes. Out of clear flood mode cranking, it wants to start, and it tries but will not run and eventually stall. Scan data pids also show crank signal missing is "false" when cranking as if this PCM is seeing good signal but I cant get one to save my life on a scope. Now im fairly new to scoping, so I have checked my connections and ground several times, even swapped around my leads and probes. I don't believe its in my set up. So I look into my ASD relay and can see I have no power from it on coils or injectors, however I have good circuit and control, and I confirmed that by back probing into my coil and injector power by ASD relay and can toggle it on and off with scan function. In TIPM I have no ground control from PCM to turn on that relay with key on or crank. So I bypass it to see if my starting condition changes. still nothing. Now im going down to the crank sensor because I try not to ignore the data, signal is bad. There is no logic in service data of pull-up or pull-down hall effect on this sensor, just generic hall effect signal generation. That's when I came across Danner's videos and look to do some more testing when I'm back on Monday. However, I do know I have 5v on my signal wire with sensor disconnected, that would indicate I have a pull down sensor correct? If so, the last thing I can think of is checking that signal wire for short to battery or another 5v in that harness? Been caught up in this thing for a few hours end of day Friday so I used the weekend to take a break from this and see if I can seek some help or guidance here. I guess my main question would be; Where would some of you guys start with this data so far in this situation? Scratching my head a little bit here. Thanks. 

Sorry, I didn't see this post yesterday. It sounds like you've done a good job checking the crank sensor circuit. You can try a bypass like Scanner Danner does in some of his videos by disconnecting the crank sensor connector and rapidly touch the signal wire to ground and watch for RPM on the scan tool. You have cranking RPM in the data, so it sounds unnecessary as of right now.
It's hard to see, but it looks like you have the scope set up at 1sec? That may be too much time to catch the crank signal, you may want to try setting it up @ 500ms and see if there's an appreciable difference. Based on what you're seeing in the data, it sounds like the PCM is seeing the CKP signal.
I didn't see it in the post, does the engine have spark and injector pulse while cranking?
One more thing to note is that the ASD relay is only active for a couple of seconds after you key on the ignition. It would be perfectly normal for it to not be on (and thus no power to the coils, injectors etc.) by the time you get out of the truck and start making checks.

Hey, thanks for the reply.

Yes the 1sec on the time base was easier for me to see while cranking from in the cabin. I have a same crappy signal at 200ms.

As far as the bypass goes, yes I gave that a shot. Seen one of those videos shortly after this post. My data pids however, only show “engine speed” and there’s no change. I believe those on the videos were “crank count”

Thank you, I have done all that I can think of and now. Today I checked for a potential short to another 5v in the signal wire to PCM just to see if maybe something else is keeping it from pulling to ground. While I was there I checked shorts to ground and power on all reference, ground and signal. No faults.

I then brought in a good known 5.7 from my lot. I swapped crank sensors and same crappy signal on this vehicle, and good known donor cranks and runs. With this good known, I confirmed I have a pull down sensor, and that the vehicle will not run without a crank signal, by unplugging the good known from the donor and attempting to crank.

You know I think I got so caught up in this crank sensor signal, that I only checked ASD power when cranking and not control on coils and Injectors. I will do this tomorrow as well as update photos with my data pids while cranking with this crank signal I’m receiving.

Okay, that is good to note on ASD timeout. I have ASD demand and “on” state when cranking, however I don’t crank it long to avoiding flooding while I am cranking with fuel pump fuse In.

Everything I have checked has me at the remedy needing a PCM but I just don’t feel good about that call! I don’t have anything solid to condemn it besides a sensor that won’t pull to ground, and a no start condition. Nothing else, no codes, no bad powers, 5v refs or grounds.

Another attempt to receive good signal is I cleaned the block very well at the crank sensor hole. It’s rusty but cleaned and cleaned several times, no change in waveform.

I’m grasping at straws here! Thanks!

Little update.

I did check for control on coils and injectors, I have none. Control is directly from the PCM, which I can only now assume is because it is receiving bad crank signal. There is no logic in service data saying PCM control to coils and injectors are driven by cam signal, which I do have. Here are some waveform I took today and 500ms and 200ms. Still no codes, PCM data in scan tool is saying it sees crank signal, there is RPM, and cam and crank are “in-sync”. I feel like I have to be missing something here.

I think you need to "zoom in" further still. Try 20ms. Since you have a running truck, set up on that one and play with the time base untill you get the crank capture you are expecting, then keep those settings for the no start CKP.
 
Do you have power on pin 30 and pin 85 of the ASD relay?
It's weird that the scan data points to the crank sensor being present. I think there is a data pid that indicates the control status for the ASD relay. I know you can command it on, but it would be nice to see the command status while cranking to get an idea of if the computer says it is trying to activate the relay while there is no control.
Keep us posted!
 

That's a good idea, and I was telling myself to do that on the good known while in the shop lol. it's a 2019 5.7 Cricut is the same, with some differences like PCM, mounting location and pinouts. However, that 2019 did run with the crank sensor installed that is giving bad signal in my 2016. 

I also tried 20ms, same result, just erratic and at times a drop to ground. This is at the sensor and at the PCM signal. I usually start with the 20/20 rule if I'm in the 4-channel scope. I also tried the presetting in guided component test with the Zeus when selecting CKP sensor.

Yes, while cranking, I had my scan tool on ASD state and also had more scope leads in an injector and a coil ASD power. I get power all the way there.

With a test light, I did confirm power on both 85 and 30. Even used a relay bypass while cranking to see if I can get it to start, no luck.

I will capture a still on my scan data of the relevant pids I am using while cranking.

Will update soon. Appreciate the help.