Alterego

@Rotket for sure go after the miss.. you can also do a leak down test since you are going to have the injectors out. Pull each piston up on its stroke with all the valves closed on the cylinder. And apply shop air pressure with a leak down tester and then see if it holds. If you have a bad valve, seals, or rings that should tell you. The pressure will leak down very quickly and you will hear where it is coming from. ( make sure you have the crank held in whatever position you apply pressure or it will move.) I did this not long ago and found out number 5cyl had a broken ring even though it would pass a compression test.

The truck you have listed is a 4x4 right. It might sound far fetched but I have seen it before. The pinion bearing can make sounds like that and project up and sound like a belt or idler going bad. They usually act up when loaded and then quit when unloaded. Being that these trucks(at least from the ones I've delt with drive the front drive shaft all the time, when you accelerate it loads the pinion then when you let off it unloads and quits making noise. Check your diff fluid and play in the pinion could be a bad u-joint as well, but I have seen pinion bearing do crazy stuff on the big 4x4's I use to build.

@the7t7 if you have high resistance in one of your ground paths it will drop your voltage, and give you the condition you have now. There is a good article on here about the ground mod that fixes alot of issues.

The easiest thing to do is drop your starter and pull the CPS then with a mirror or borescope check the tone ring. I fought the same problem for a few months. It can be fixed without pulling the motor, as long as you have some patience. I'm working on a write up to detail the whole thing. Dodge no longer sells the parts but cummins has them for about $150 you will get the tone ring and 5 screws that hold it in. I have part numbers, torque specs and a tool list. Pics of the position the crank need to be for install.

@the7t7 dumb question I'm sure but have you checked All your grounds. In my recent adventure pulling all the engine wiring harnesses. The grounds are junk they are just bundled together and crimped in a metal clip then covered with sub par heat shrink. I ohmed mine out and replaced all of them with solder sleeves then added adhesive aviation quality environmental sleeves. @Mopar1973Man said the ecm wont boot under 8 volts. I would check your power and grounds to the ecm and see if you can correct it there. Dont give up. If you have a power probe you can induce voltage and check circuits that way, just be careful there are some circuits that use reference volt of 5 volts and putting 12volts to them is not good. Power probe makes a 5volt adapter for there system.

@int3man mine is a 98 3500 4x4. @Tractormanthanks for the comment. I'm starting a write up today that has the whole problem and procedure detailed. I learned alot with this issue. As a really good friend of mine who is one here said knowledge is power. If sharing can save someone the headache then it's well worth it. Plus I dont give up, I'm the type that will fight it till i get it fixed. @Mopar1973Man hit me up when you get a chance. Thanks to everyone for there input. You guys are the best

All done and running. Tone ring can be changed without pulling the motor ?

Ok big part is on it took some romantic persuasion but it's on with no damage

To bad you guys aren't close enough to come help with this or at least give moral support.

@Mopar1973ManWill do. This has been a huge learning experience. And I will gladly share anything I can

Found it in the ram forum.... You have to pull #6 main bearing cap off, then pull #6 rod cap off. You might have to rotate the engine to get the cap off. The ring is in 2 pieces with 5 screws holding it all on. Take the small section out first, then rotate the engine so the gap where the small section was is facing up. Then you have to manipulte the large section out. Assemble in reverse order...The tone ring screws torque to 71 in lbs...and use blue loc-tite on them. Main bearing cap...45 ft lbs, 66 ft lbs, then turn bolts 90*. Rod cap...22 ft lbs, 44 ft lbs, then turn bolts 60*. Oil pan bolts 18 ft lbs. I'll let everyone know how well it works out hopefully will be up and running by lunch tomorrow...

Yea I got all the parts in the bottom of the pan. Everything is accounted for. The issue now is getting it back on without pulling the crank @JAG1 I have tried to find a way around it with no luck. Destrocked diesel has a 35 minus 1 tone ring kit that mounts to the balancer but According to them it wont work as a replacement for the internal ring

Do you have any suggestions on the installation. I'm trying install without pulling the crank. I've got the cap off but there doesn't seem to be a way to install it without pulling the crank

Old tone ring out. I'm not sure what happened and I am very lucky that there is zero damage to anything inside. I hope this is a one and done deal.

@JAG1 first off all input is much appreciated. I know sometimes as a life long mechanic we tend to dive right in and overlook the obvious. To answer your question yes sir all connections have been checked cleaned and "bond checked" to their respective components. All the harnesses have been removed disassembled inspected cleaned checked end to end for any failures, then reassemble to aircraft specs all bend radius of wires have been set to 6D or better. Then everything was loomed up and taped all the joints that could have been an issue have been changed out for solder sleeves then adhesive heatshrink on top of that. It has come down to the last thing in the equation, which is the tone ring. I wasnt aware it was a bolt on ring until @mopar1973man brought it up. But with the logic of the ECM and a signal that doesn't agree with the other inputs. I'm confident that once I drop the pan I will either find pieces of the ring in the bottom or the small removable section sitting there. I will post pics and updates once I get into the bottom end. Once again thanks to everyone for all the information and input Ok everyone so after getting the oil pan loose enough for me to see inside the tone ring is broken. It has sheared in half. So got a new tone ring and will post pics once I get the pan off

@pepsi71ocean yes SAI electronics did test my original ECM. They do not sell replacement parts so... I started looking and found automotive module source.. I ordered a replacement and same issue so I assumed by everything I heard that ECM was not right, so sent it back got another and still same thing. The 3rd ecm came from a friends truck that I swapped in to see what would happen. I do have to say AMS didnt give me a single issue swapping out the ecm and did everything they can to make sure it was right. I know the ECM they sent me is good because it runs great in another truck. I've think with the help of this forum, it has been narrowed down to the tone ring on the crank. I'm going to explore an external option and completely remove the internal one completely.

@Mopar1973Man it is the original block in the truck no motor or cam change. It just happened one day. Drove to the store, truck wouldn't start, grabbed a CPS and changed it truck started but tach died thought is was a bad CPS changed it again same thing. Sent ECM off to have it tested was found bad, changed ECM now 3 times and the same issue. Didnt realize the reluctor ring was able to move or I would have checked it. Truck ran fine until this event. The reluctor ring is the last part of the equation. I was looking at the other link you sent me with the swap problems and saw the 36 minus 1 external pickup I'm going to give them a call in the morning and see if that will replace the internal ring. If it does I will go that path till I get time to go into the motor and reset the internal one.

@pepsi71ocean I did check the cluster as you suggested a couple weeks ago. I even pulled it from the truck and ran the truck with it out, still runs the same. I have checked it fully. @Mopar1973Man the more I learn the more I understand the logic in the ecm. I haven't found a logic tree for the ECM yet but. I think I have figured out. That the truck has 3 timing signals; crank, cam, and injection pump. The truck will run if it can denote that the injection pump is in time with the cam but with the crank sensor being "off" it nulls that signal, which is when the tach dies and the engine then runs off the 2 signals that match. There must be some sort of "or" gate in the logic that allows this to happen if one of the signals is lost..... So I have come to the conclusion that the reluctor ring on the crank has slipped and is now slightly off, thus the engine running ruff on start up until the logic nulls that signal out due to the mismatch. Please correct me if my thinking is wrong.

I'm going to order longer leads this morning for my o-scope should have them by tomorrow afternoon then yes I can drive with it hooked up. This is the events as they happen. It doesnt matter if the edge is hooked up or not and keep in mind it's the same thing with multiple ECMs and all the wiring has been removed from the truck and checked end to end all sheathing removed and wiring completely inspected. All the crimp splices have been replaced with solder sleeves then have adhesive heatshrink on top to completely seal them. Ok now for the events as they happen. Key on air dog comes on for a second. Preheat light comes on and then goes off approx 10secs. Clutch depressed key to start. Truck fires right up. Sounds like it's missing or timing is off. Tach is active for about 20 seconds. Tach then dies and torch smoothes out and runs normal. As all this happens with meters and o-scope hooked up. The 5v input is constant, on a second meter measuring resistance the ground is constant. On the o-scope the signal and frequency remain constant. With the edge hooked up the rpm displays and it is correct and matches the engine rpm. It matches the external optical tach. Today I'm going to drop the starter and check the reluctor ring. If I can get the oil pan off I will check the air gap. I'm looking for a spec for that now.

Yes sir. I did the above checks. With the harness out of the truck and again with it back in. Perfect continuity from end to end. No shorts pin to pin. 5v coming to the sensor and a good ground back. With the O-scope hooked up the sensor seems to be working as it should. I felt in the hole to see it the ring is loose but really can tell so it looks like the pan will be coming off. Not sure if it is possible with the engine in the truck. The thing that really bothers me is that with the Edge hooked up I get a tack reading on the display. And once the cluster tach goes to zero the truck runs stock as a stock truck.

First off thanks for all the replies.. so here we go... problem is still here. I have swapped the ECU out several times now with several different units. Even borrowed a buddies truck that has the exact same drive train and put my "new" unit in his and his in mine. His truck ran fine with either unit, mine on the other hand still has crank sensor code, tach dies after 10 secs. I completely removed my edge before any of that. All of the Under good harnesses have been removed and checked completely for shorts pushed pins. Ground mod is done. Alternator mod is done with the field fuse installed. I'm thinking about going and buying a mopar brand crank sensor to see if maybe the air gap might be the issue, but with a test light I can see it pulsing and the sensor is getting the correct 5v reference. I'm totally frustrated with this now and the whole keep throwing parts at it is not my style. I did also check all the under dash wiring and also removed the cluster just in case. The cluster did check good with it's own test. Thanks to everyone. When I get it figured out I'll post the solution for sure.

So after several hours of staring at wiring schematics. And everything else I've done I think I'm going to go after the wires under the dash. It's the only thing that makes sense to me now. Please jump in a correct me if I'm wrong but a short to say the tach behind the instrument cluster could feed back into the ECM and cause my issue. Has anyone else had issues with wiring under the dash.

I am luck I have access to a plotter and have those prints on large scale. I printed them from the electrical section and that is how I checked the wiring from the pinouts to the harness everything seems ok. I cant really use my TDR on it except for the CAN BUS twisted pairs, and to use a megger on it would be detrimental to the harness. So I used a fluke 78 to ohm out the harness. I was going to o-scope the signal but not sure what the pattern should look like. My o-scope has 4 channels so I could do the crank and cam at the same time.... this is why I'm at a loss. I am reaching out to the experts. I'm at the point to just replace the whe harness and both boxes again, but I have a feeling this wouldn't fix it as I have already checked it all out. Also I have move the grounds that dodge spliced all together to the LH side of the timing cover and ran 2 8 gauge ground wire directly to the battery. The PCM ground was checked and I removed the plugs and ran straight to the negative terminal of the battery. All the battery wiring is 1/0 stinger battery cable and both power and grounds of the batteries have been redone that way and both batteries are interlinked with 1/0 cable all terminals are soldered and have environmental heat shrink that completely seals them.

Thanks for the replys. Yes I have completely removed the edge. And it did the same thing. This truck has both sensors the crank behind the starter and the cam under the vp( what a pain to get to). I have changed the sensors. The ECM and PCM where tested by SIA electronics and the new PCM came from Auto Module Source in Florida. I have checked all the references and they are 5 volt plus or minus 0.1 volt used a test light on the signal and it shows good. I was told the signal from the CPS goes to the PCM but from the wiring I can see it goes straight to the ECM 2 wires on one side of the connector and 1 on the other I think it was pin 6 and 16 and pin 2 if I'm not mistaken. I'm crossed eyed from pinning the whole harness out the past 2 days. What really gets me it happened all of a sudden like a white snapped or component just failed which from my experience doesn't happen very often.

First off I'm new here but hope I can contribute in some fashion as well, 2ndly I hope everyone had a very merry Christmas. Now the truck then the issue. 1998 24v 3500 4x4 manual transmission. Mods are air box, full exhaust, hot rod vp44, air dog 2 165, edge juice CS w attitude, and the wiring harness mods listed on here. Ok now my problem.... driving the truck one day and it shuttered out of the blue didnt think anything of it and kept on going. A few days later it does it again and the tack dies, doesnt come back and I notice the levels on the edge dont work anymore and the truck is running bone stock. No codes or check eng during this time. Picked up wife to run some errands stopped by the auto parts store wouldn't crank back up. P0336 showed up so walked back in the parts store got a crank sensor slammed it in and truck fires up tach is back for about 30 seconds truck runs rough tach dies motor smoothes out. P0336 code is there. Shut truck off, restart same thing starts right up tach is up for maybe 30 secs then dies and truck smooths out. So what I have done..... I removed both ECM and PCM sent them both to be tested. ECM was bad so replaced it. Removed all wiring from the engine bay, undressed it cleaned each and every connector and fixed all the grounds. Ohm'd out each wire from start to finish and validated no brakes or anything else wrong with the wiring. Put it all back together and still the same thing. I forgot to mention I have changed the crank position sensor 3 times and the cam position sensor once. I have come to the end of my rope. I would greatly appreciate some advice. I have followed every step of troubleshooting I can get my hands on. Hopefully it will be something stupid, if it is I will gladly put on the dunce hat. Quick note I forgot to add that is important I think. The Edge display I have set up to show RPM and it never drops to zero it is following the engine and is correct. Thanks in advance Alton