No power to cam or crank sensor. Help please!

Correct that is the ECM ground.

What else do you have grounded there??

 

That isn’t my truck lol just a pic I pulled up on the web. I do have mine grounded there tho

 

Just make sure that it measures less than .5 volts with your voltmeter and you're good.

Also, do not cut into the harness! You want to be the least invasive here as possible! The idea is to backprobe the harness inside the connector while it is connected at the PCM and then hook up your lead to the probe and your ground to a clean good body ground. Not frame ground.

 

Do you happen to know which one I’m probing for the cam and crank sensor!

 

Not off the top of my head. It's not the brown at the crank sensor that I know for sure. Because the brown wire is ground. You have two potentials left. If you see 12 volts on one of them and if you see 0 on the other, that's a solid thumbs down and it would indicate either you have an ugly short circuit OR you have a short circuit which took the computer with it and if you replace the computer there is a good chance the computer again because there is no fuse between the PCM and the crank or cam sensor.

 

So if I replace the computer there is a good chance it will get fried again if I have a short? I really hope that doesn’t happen. Should I just hunt down a break in my wire somewhere?

 

Shit, I forgot to write that there are three possibilities the third one is that the computer just went on its own which they sometimes just do without warning.

You may or may not have a short.

The best way to check for that short is to do a continuity check at the sensor plug for the crank and cam sensors and at each wire for the 5v reference at the computer side. Most wires usually have a .003- .007 ohm reading. Get to it.

 

@Scesare1 it SHOULD be the red wire at the CKP sensor, but check with the ignition switch switched to the ON position.

 

Okay so both cam and crank sensor passed the continuity test. But the readings at the back of the ecm was not good. Assuming the computer is messed up on that circuit. Also the fuel pump is randomly not priming anymore. Can’t hear it when I turn the key to the on position. Does it run off the cam or crank sensor circuit? It was working a few days ago. Before I tried starting my engine after rebuilding it I made sure to drain all the old gas. So it was for sure working. Now I can’t hear it turning on

 

Question. Is your check engine light turning on when you turn your key to the on position? Have you checked all of your fuses by the way, because if the computer isn't even powering on due to a blown fuse, of course it won't energize all the vital items.

 

Yes CEL is comin on. All the fuses are good. Wondering if I just burnt up the pump draining the gas. Hope not

 

Some circuits are reading just fine at the ecm. Nothing from the crank/cam wires tho.

 

You are getting 5 volts at other circuits?

If your CMP and CKP sensors are not sending out a 5 volt reference then your PCM is fried at those circuits.

 

Yessir I believe the ecm is fried at those circuits. Will be buying a new one. Hope the new one doesn’t fry somehow. No shorts so I don’t think it will. Thanks for all the help with that! Will get back to you on this thread with an update once the new ecm is in

 

Also took the ecm apart and did a visual inspection. Everything looked fine inside. No burn spots or anything. But like I said, wasn’t sending out voltage

 

Nah you will never see burn spots on a computer unless something wild happened and if a circuit is just dead you will not see that either. Good luck man. Let us know what happens!

 

Well computer came in today. Still nothing. Now what? Completely lost

 

Are you sure it is a good PCM? I've had replacements fail before.

 

As far as I know. Hate to buy another

 

Could open circuit relay mess with it or anything ignition related?