Rusted crankshaft sensor

Hello,

If you are going to replace the Crankshaft Position Sensor [CKP], then I wouldn't worry about hurting the old one. Keep the electrical connector away from the PB Blaster and douse where it is rusted at. The main thing that you want to preserve are the threads in the bolt hole. The CKP, once free from the rust, should just pull out, it's the bolt, obviously, that secures it in place. Please get back to us with how everything turns out.

Thanks,
Alex
2CarPros

Did you have any luck getting it out? The way that is rusted makes it look familiar. What is the reason for replacing it? Engine refuses to run?

The o-rings can get really stuck in there. I've used a few things to get them out over the years. What is the code you are getting? I have seen a bad cam position sensor trigger a false crankshaft code before on them. How did you test the sensor?

As for getting them out, I've used heat on the block to bake the o-ring and melt the outer case of the sensor enough it comes free. I've also sprayed lithium grease in there and pried on the parts outside the block. I've even got ticked off and smashed the outer part off so I could get into the hole and clean the rust out. To do that requires that you drill a hole into the sensor and put a long screw into it, then cut or smash the outer part off and go after the rust. I've also known of folks who just snapped them off, then dug them out with a die grinder.
Where are you stuck?

Sounds like he knows his stuff pretty well. Your codes are both intermittent circuit codes. That means it could be the sensor or it could be the wiring. Do you have access to a multi-meter? If yes you can test the wiring between the crank sensor and the PCM. Also follow the wires themselves, look for any damage or corrosion as those two share the same sensor ground. Would also test the sensor as it seems to have failed now and should show as bad. For that you need the multi-meter again. Or as an emergency test, take a jumper wire, and find the dark blue wire with a dark green trace on it in the wires to the crank sensor. Bare a small spot of the wire and connect the jumper wire from that to battery negative. Stick the bolt back in the crank sensor and see if it fires now. If it does the sensor ground wire is the problem.

If the engine will start it likely isn't the crank sensor that's bad. Those usually just fail and done on those engines. However being the codes are both intermittent circuit codes and that Jeep being rusty a bad ground or corroded splice are both very likely. Finding it will be the difficult thing. The first place I would look is the ground wire they both share. If the meter you have has a continuity beeper it could make it easier. The visual inspection I mentioned would be the first thing though. Don't be afraid to open the wiring loom and trace the wires. There are numerous line splices that could corrode or the wires may pass over a spot where the loom rubbed through.
The meter can be used with the engine off for some tests and the key on for others.
There are a lot of guides for meter use out there, they may not match exactly to the meter you have but ohms are ohms, volts are volts.
https://www.2carpros.com/articles/how-to-use-a-voltmeter

3.5 is very low. That could be the entire problem. You should be able to measure 5 volts or very close to it. Measure between the Dark Blue wire with a Dark Green trace and the Pink with Yellow trace wire with the key on. You want to see 5 volts. Then go to the cam sensor and check between the Dk Blue w green trace and the Yellow wire with pink trace That should also show 5 volts. If not you have a problem. The Dk Blue wgreen wire is the ground side, the others are 5 volt reference feeds from two different connection pins. The other wire on each sensor is the signal output. If you find 5 volts at the cam sensor but still 3.5 at the crank sensor, take the negative probe and put it on the negative battery terminal and then measure the crank signal voltage again. If it's still 3.5 then the ground side is OK and the problem is on the feed side.

It shouldn't be unless it;s cracked. They are designed to be run in hot oil and corrosive gasses in the engine. The connector side is a bit less forgiving but a spray with some contact cleaner should get the PB out.
As far as the wiring, It would depend on what it actually is. If you measured the voltages and found one is 5 volts and one is 3.5 then it may be just a corroded connection at the PCM. Or it may be internal to the PCM. That was one reason I wanted you to measure them both and to ground as well.
That isn't that bad for a battery, it's showing some age but if it turns the engine over and reads 12.6 volts setting still it shouldn't effect the measurements. That's one of the reasons why the sensors use a 5 volt reference voltage. When you are cranking and engine the starter pulls a lot of power and that can draw the voltage down to 9-10 volts as it cranks. If they used a reference voltage of 10 volts it could easily cause problems as the voltage dropped lower. So they use 5 volts which they get by running a simple regulator inside the PCM. That lower voltage is safe because it's below what the draw should be and much of the PCM is nothing but a computer designed to run on 5 volts anyway.

That's all that anyone can ask. If you run into issues just ask.

Intermittent codes can be wiring or part, that is why you test both. In this case I would say it's the wiring simply because of the readings you are getting and it being a Jeep that are known for wiring and ground issues. If you think the voltage was wrong, test it again. You should have real close to 5 volts there, low voltage will cause the sensors to work intermittently if they work at all.