Here is a way to check hall effect sensors(cam/crank). You will need a T pin to probe the connector.

 

I know this is a crazy old thread but it's the closest to the exact problem I'm having and I can't figure it out I'm at buying a new PCM stage. I've tested cam and crank sensors changed them both two or three times. New I AC valve new fuel pump. New battery new rotor and cap. New ignition coil. I have the power to the coil but no spark out and I also am at the noid light testing stage. The tests seem to leave unsureity without a scope but I see a new PCM didn't fix the issue. This truck simply didn't start at the gas pump and I can not get it running. After all of the reading on this Im pretty sure the sensors are working because the PCM is sending signal or reference. Also it protected itself during testing where it shut the 5 v reference off until I turned the key off and on. I am completely stumped and out of ideas other than trying a new PCM and if that doesn't work, well that's messed up. And the fix isn't in this thread. Please help me.

 

Five volt reference should always be there. ASD powers the coil, and injectors. PCM will trigger asd for about 3 seconds at initial key on, after that, only if it sees the engine turning.

Need to see what is missing when it won't start. Fuel, or spark. (or both....)

 

I’m having a similar problem with my truck now after doing the plenum gasket and front timing cover gasket. Got it back together originally had screwed up and put the plug wires on one position out, fixed that and it fired up and ran beautifully. Had to get a replacement idler pulley because the sound it was making and after I changed that now I have crank, no spark, can smell the fuel out the tail pipes, no power to the coil but have ground, and the tach moves when cranking. I spent 2 hours trying to figure out what it could be. I do have a new PCM on the way because I had an extreme mistake and touched the coil power wire direct to power with the power probe because of frustration and not paying attention and head the PCM go pop and then saw smoke and you can smell it. I’m lost as to what could be going on now. Can’t even run it to see if the ticking noise there now.

 

Replace the PCM first, and see what happens. If you let the magic smoke out, chances are very good that it is NOT going to work any more.

 

Will update as soon as I get the new pcm. Should I get a new crank sensor for it?

 

Not yet. Besides, if your tach is bouncing while cranking, that implies the sensor is working.

 

Ok that’s what I thought but wanted to double check. I have the availability to run a working pcm and test but it’s from a 318. I’m more knowledgeable if the diesel realm of dodges so I’m going to assume that putting that pcm on will not work.

 

What year truck is it from?? It may be enough to get the engine to fire, but, yeah, it prolly won't run that well.

 

It’s from a 98