I've been trying to diagnose a crank sensor code on my '99 V10 for about a month now. Just now got around to ohming out the crank harness and engine harness.

I'm getting 2 mega ohms at the crank sensor harness between sensor and ground without the engine turning. Does that sound about right or too high? From what I've read most crank sensors are only 750-1k ohms. I cranked the engine to recheck, at which point I got no continuity to the sensor contact. After cranking it again I got the same reading as before.

Resistance from end to end of the engine harness to the crankshaft sensor plug is about .3 ohms on each wire. Doesn't seem to be any breaks or bad solder joints.

This issue started out a couple of months ago after I tore my engine down to replace the camshaft. The thermostat was also stuck open, so the engine was previously not getting up to operating temp. After all the work was done the engine ran perfectly fine until it got warm, then it would sputter, backfire, and die. I could usually restart it immediately, but not always. I pulled the crankshaft sensor code and replaced the sensor. The engine initially ran better, but started dying just as before when it got up to temp. Since then I've been driving it around my farm, and the problem has been getting progressively worse. Now I can barely run it for 5 minutes before it wants to die and then I have to wait an entire day to restart it. It seems like the only thing that could be the issue is that I got a faulty crank sensor somehow.

 

I think I saw that on the second gen Facebook group lol. Anyhow, that 2 mega ohms sounds high.

 

Haha Yep, indeed you did! So far I'm getting no bites. Gotta hit up all the social medias.

 

What brand crank sensor? And what code, exactly, are you getting?

 

Walker 235-1116.

Just now looking back at my codes and for some reason I didn't notice I was also getting a Cam sensor code! Oh no...

P0340 - No cam signal at PCM
P1391 - Intermittent loss of Camshaft position or Crankshaft position
P0320 - No crank reference signal at PCM (before the new crank sensor)

Maybe the cheapie camshaft sensor I put it is bad and I just misread the codes on my screen? I feel like a dummy, but good at the same time.

 

There is a specific procedure for installing the cam sensor.... and if you don't do it exactly right, it either breaks the sensor, or, it doesn't read properly. Also, the trucks seem to be REALLY picky about what sensors they will play nice with. If you can find a mopar sensor, that would be best. I think Standard Motor Products are another that should be 'acceptable'....... Some folks get lucky, and the cheapy brands work for them, but, that's pretty rare.

 

Really? It's not just plug-and-play? Guess I'll have to read in the manual a bit...

Going out to find a walker cam sensor right now.

 

Cam sensor has an install procedure, crank sensor doesn't need anything special.

Both sensors are hall-effect type so measuring resistance doesn't yield any clues. Ideally these are tested with an oscilloscope but that's typically not possible for DIYers. You can try to use a voltmeter on the signal wire and see if there are 0V-5V transitions. Pull the fuel pump relay so you can do that at slower cranking speed.

 

The firing sequence is controlled by the crank sensor, the cam sensor is a reference to tell the PCM where the crank is is the 4stroke cycle. The engine may run with the last known good settings for a second until the PCM realizes there is no cam signal, failing almost immediately. Cam sensor failing due to heat after several minutes is fairly common. Also, because of the low voltages in these circuits testing for voltage drop may show you more than resistance. Good luck, let these folks know how it turns out.