I will let the mechanic know that he should be seeing a 4:1 ratio of crank:cam sensor counts. That should tell him if the sensors are doing what they are supposed to. If that checks out, then it seems the possible causes are narrowed down to:

1) Bad PCM
2) Wiring problem (maybe a bad ground connection on the coil circuit?)
3) Failed ASD relay (though the mechanic says he jumpered the relay and still got no result)
4) Injector problem (though I don't think this is the case, since there is no power going to the coil, and it smells like gas every time you crank the engine)

Am I missing a possibility? It seems like if both the cam and crank sensors check out, then it can't be a timing problem. If there is no power going to the coil, but the cam and crank sensors are working, then either the PCM or a wiring problem have to be at play, right?

 

If you aren't getting power to the coil, or injectors, and jumpering the ASD relay doesn't help..... I would be highly suspicious of the PCM.

 

If I purchase a remanufactured PCM, will I need to take it to the dealer to have it programmed? And if so, can this be done off the vehicle, or will I need to have the truck towed to the dealer for this to be done? If done off the vehicle, do I just need to provide the dealer with the VIN and accurate mileage?

Thanks!

 

Maybe sounds stupid but.. Battery voltage good? I always check the dumb **** like that first.

Also as a **** wrench but a EE, you should have no problem checking the switched side of the coil with a digital multimeter. When the pcm cuts the ground, the terminal will float up to 12V same as coils other side, and when the pcm reconnects ground, it'll hit zero, and it does this at some rate whatever it is giving you a 0-12v square ish wave. Switching between 12v and ground (with 50% duty cycle) will give you 6v on the DC Vreading and some amount about ~12*.707 on the AC V reading, depending on your meter.

Nick

 

Any decent shop should be able to program it, if you buy locally, they will more than likely simply ask for your vin, and it will come already programmed. If not, you can put it in your truck, and drive it, but, things like the ABS, and SRS lights will be on.

 

I'm sorry to resurrect an older thread, but unfortunately I am still trying to figure out my no-start issue. I purchased a remanufactured PCM that came pre-flashed and VIN-programmed, and the truck will still not start. So now I am back to square one, and I assume at this point the problem HAS to be an electrical/wiring issue? The only curious thing about the new PCM is that the mechanic said he is no longer getting a code for no power to the coil, which the original PCM was setting when the engine was cranked. He's going to go back through and make sure there is nothing stupid like a disconnected wire or something and re-check voltage at the coil, but I'm not optimistic about that.

So, to recap, here is a brief synopsis of what happened and what we have tried:

-Truck died while driving; first the transmission slipped/shifted into neutral, then about 5 seconds later the engine shut off. I restarted the truck and drove another 1/4 mile or so, and then the same thing happened. The truck has not started again since (that was in June).

Since then, the following has been done:

-The crankshaft position sensor and camshaft position sensor have both been replaced, and my mechanic says he is seeing signal from both and his scanner says they are synched.

-Fuel Injector pulse was checked - seems normal, and you can smell fuel when cranking the engine

-New Mopar ignition coil was installed

-ASD relay was jumpered; still no power to ignition coil

-New PCM installed - still no start


So, do we need to simply start tracing wires, starting at the ignition coil and working our way back through the harness? That seems like it would be a nightmare, but may be the only option if I ever want the truck to run again.

If anyone has any input or ideas about other things to check, I would greatly appreciate the input. Thanks!

 

Yep, got a broken wire between the ASD relay, and the coil. Check under the PDC first... if it isn't obvious there, while it's loose, follow the wire from end to end.

 

I guess we'll get to tracing. I may be nearing the point where I need to have the truck towed back to my house so I can just work on it myself. The mechanic working on it is probably sick of looking at the thing by now. It's been in his shop for 4 months! Haha.

Hopefully I'll be able to report back with some positive news soon. Thanks again for all of your help.

 

The mechanic hasn't been able to find any wiring issues yet, although I don't think he's had much time to devote to it the past few days. However, he reminded me of something that really puzzles me - he says that all along, when you turn the key to the "On" position (not start), there is voltage on the ground side of the coil connector for about three seconds, which is what I think is supposed to happen. Of course, as soon as you crank the engine, the ground circuit fails to be commanded open/shut by the PCM for whatever reason. This is what made him think that the PCM must be the problem, rather than a wiring issue, because it seems that the ground circuit works when you first turn the key.

I am completely stumped. I'm going to ask him to keep tracing wires, but I have this nagging concern that something else is going on. Is there anything mechanical (other than the cam and crank sensors) going on that could be causing the PCM to keep the ground circuit open? I know in my Isuzu Rodeo there is something called a "range mode sensor" which tells the engine control module what gear the selector is in (drive, reverse, low, etc.), and if this sensor goes bad, all sorts of weird things start to happen because the computer thinks the transmission is in a different gear than it actually is. Is there anything similar on the Ram that could be at play? The transmission slipping/going into neutral was the very first sympton when the truck first died, so that has always made me wonder if there was some correlation to the problem, or if that was simply just a product of power getting cut to the coil for whatever reason.

Thanks again for all your help, Hey You. Your expertise is very much appreciated!

 

If you are getting power to the coil at key-on, for three seconds, things are working as they should. Should also see power at the coil while cranking the engine. Check for that next.