I have a 1996 Dodge ram 1500 5.2 magnum automatic 46re transmission. I've had the cam crank loss code coming up since I bought the truck last spring. Once it got below zero something failed. It stayed around zero for weeks. But I started with the crank sensor. That didn't work. I then did the fuel pump. Then the Iac valve thinking it was frozen shut. New battery. Finally it got 30 degrees or so out and It started. Drove it for a week and it started not wanting to start. Noticed the cam sensor harness from the engine wasn't stable the truck was shuddering when I moved the harness. This took me forever to happen to wiggle and find the issue. I didn't want to take the distributor cap off and such so I ended up hardwiring the wires without connectors and it ran for a couple weeks. Then wouldn't start at the gas pump. Since then Ive put in another crank sensor two cam sensors because I wasn't sure during testing if it was actually not switching. And now put in a new ignition coil because I can't get spark. I've backprobed the black white wire and the voltage comes on for a sec goes off. Key on goes up and crank it fluctuates from 10.8-12v kind of jumpy on my digital multimeter. So I think my crank and cam sensors are good because of the power and I also backprobed the crank sensor harness and saw it switch from 5 to 0 volts. But I had to stop the crank to see it otherwise it's fast. My PCM seems to be behaving as it should with protection and the asd clicks with key on and pulling the relay in and out. I don't see any fuses out. I'm going to try another new ignition coil and then I'm basically at a new PCM! From what Ive read it's rare for the output drivers to go bad on these and another thread the guy tryed a new computer with the same problem and nothing. The thread ended before the solution and I need it!

 

Cam and crank sensors should get a 5 volt signal, if you are seeing 12 volts on either/both, you have a short somewhere.

 

Ok I put a new PCM in because the signal didn't seem to be grounding from the PCM to the coil for signal. Now with key on the light flashes briefly. Then on crank comes on and stays on but dims down. Then shuts off when not cranking. Coil harness testing shows no short to ground. New ignition coil and have another. When plugged in the other new one the light stayed the same so I didn't try it yet because the resistance is fine. In other words I have literally tested everything over again with a new PCM and still not getting a start. Right now I'm at charging the battery and trying a spark test again by filming. I've been solo doing this for a long time piece by piece and basically can mentally picture the system and still missing something. Inspection of the wiring without opening the plastic loom housing stuff there's no visible wear it's all pretty clean. Unless there's somewhere in a branch but all voltages are at spec and nothing I've caught out of ordinary.

 

Ok I put a new PCM in because the signal didn't seem to be grounding from the PCM to the coil for signal. Now with key on the light flashes briefly. Then on crank comes on and stays on but dims down. Then shuts off when not cranking. Coil harness testing shows no short to ground. New ignition coil and have another. When plugged in the other new one the light stayed the same so I didn't try it yet because the resistance is fine. In other words I have literally tested everything over again with a new PCM and still not getting a start. Right now I'm at charging the battery and trying a spark test again by filming. I've been solo doing this for a long time piece by piece and basically can mentally picture the system and still missing something. Inspection of the wiring without opening the plastic loom housing stuff there's no visible wear it's all pretty clean. Unless there's somewhere in a branch but all voltages are at spec and nothing I've caught out of ordinary.

 

I have a hard time navigating back to this thread I will try and respond and with better detail timely

 

Engine needs three things to run. Fuel, air, and spark. I would like to think that air isn't a problem..... so it's likely fuel, or spark. You can test spark just by lifting the coil wire up off the coil a bit, and cranking the engine. (requires a second warm body, or, a remote starter switch) The coil should produce enough of a spark to jump a 1/4 inch gap..... should be a fat blue spark that snaps..... Other possibility is fuel. Need a noid lite to test if the PCM is firing the injectors, (and you need to verify good fuel pressure.) You might be able to just use a test light.... The injectors operate on 12 volts.....

 

I tried a spark tester I'm not getting signal to the ignition coil to make spark. I talked to a guy that worked at Chrysler and he said even without cam signal if the crank sensor is working it should still have some spark. But that isn't the case I checked the signals with a oscilloscope and it's consistently no signal whatsoever from the cam sensor or distributor pick up coil. I've tryed new distributor assemblies and none of them switch or respond either even with a new computer. I've re checked grounds and everywhere for shorts key on and during crank for lias if voltage or anything out of the ordinary and nothing. Just no signal I'm convinced it's due to not getting a solid aftermarket cam sensor. Now the trucks been sitting for almost six months with all kinds of new components. It's only got 144k on it too.

 

Does the fuel pump prime at initial key on? Do you have power at the coil while cranking?

PCM won't power the coil, or injectors, if it doesn't see the engine turning. Supposedly, that would be cam OR crank sensor signal. If you have power at the coil, then the PCM IS seeing the engine turning, but, if the PCM isn't getting a signal from the crank sensor, it won't know to fire the coil.