Crankshaft Position Sensor location

Good evening,

It is at the back of the motor by the flywheel.

I attached a picture and procedure.

Roy

Thank you. Does this mean that a relearn procedure is required after replacing?

Yes, you need to perform a variation relearn after the replacement.

You need a real scan tool to perform this procedure.

I attached the procedure for you below.

Roy

Where is the crank sensor on the car listed above 2.5l ecotec? I checked tutorial photo shop and video, but i can't see anything.
Thanks

Hello,

I have included the information that you requested in the diagrams down below. It looks like your vehicle's Crankshaft Position Sensor (CKP) is located in the back of the engine above the starter. Let us know if there is anything else we can help you with.

Thanks,
Alex
2CarPros

Thanks for help me and resolve and fixed.

SCWICKEDSTANG is on of our best! Nice work, we are here to help, please use 2CarPros anytime.

I'm having quite a bit of trouble finding this sensor. From what I understand it's on the backside of the engine above the starter. I have a bore scope i'm trying to find it with to avoid taking things apart unnecessarily. Please help.

You are correct. It appears the starter has to come out for this one. I attached the process. Let me know if you have questions or still can't find it . You need to then perform the relearn procedure.

Thanks

I had a crank position sensor go bad, so I replaced it. Nineteen days later the code came back and the first new sensor had gone bad. Now I have a second new sensor and I'm trying to make sure I have a good sensor going into the car. I have test leads running from the sensor cable with T-pins to the sensor so I can check voltage across any of the three wires as I move a wrench on or off the sensor. Here are the voltages I get with each sensor I've bought when I do and don't touch the sensor to the wrench. As you can see, the two new sensors seem like the inverse of each other and the original "bad" sensor actually seems like it responds.

Original sensor:
No wrench
supply to ground: 4.98V
signal to ground: 0.71V
supply to signal: 4.24V
Touching wrench
supply to ground: 4.98V
signal to ground: 4.34V
supply to signal: 0.58V

1st New sensor:
No wrench
supply to ground: 4.97V
signal to ground: 0.03V
supply to signal: 4.92V
Touching wrench
supply to ground: 4.97V
signal to ground: 0.03V
supply to signal: 4.92V

2nd New sensor:
No wrench
supply to ground: 4.98V
signal to ground: 4.44V
supply to signal: 0.5V
Touching wrench
supply to ground: 4.98V
signal to ground: 4.44V
supply to signal: 0.5V

These readings are of no value and no one tests these sensors this way. The first problem is while you are correct in understanding these are magnetic sensors, touching metal to them is not what makes them work. Any time you want to generate a voltage mechanically, as in a generator, you need three things. You need a piece of wire, (a coil of wire is much more efficient), a magnet, (we use an electromagnet in a generator), and most importantly, movement between them. That's why we need to spin the generator with a belt.

Depending on the sensor's internal circuitry, you might get the signal voltage to change from one state to the other by simply holding the wrench close to the magnet, but not all are going to respond that way. Most respond to the changing magnetic field, and that is caused by the movement of something metal moving past the sensor's internal magnet.

The second problem is while these sensors develop a change in voltage from roughly 0.0 to 5.0 volts, unlike with other temperature and position sensors, voltage here is not what the computer looks at. It is looking at either the "rise time", when it switches from 0.0 to 5.0 volts, or in some applications, the "fall time", when it switches from 5.0 to 0.0 volts. Crankshaft and camshaft position sensors are only used for timing, not voltage.

If you're going to experiment with the sensor this way, it would be better to install it, then back-probe through the connector's rubber weather-pack seal and measure just the signal wire. (Never poke a hole in a wire's insulation to take a reading). While monitoring the voltage with the ignition switch on, rotate the crankshaft by hand and watch if the voltage changes. Remember though, movement is what makes these sensors work, so there is a minimum engine speed at which these will develop a reliable signal.

Thanks for the fantastic answer Caradiodoc, this is what I was wondering but not finding an answer to in my searching so far. So to be clear, just because the old sensor had a voltage response doesn't mean it is still good, and just because my second new sensor did not doesn't mean it is bad straight out of the box.

That is correct. Snapon Tool Company had about a $50,000.00 engine analyzer about 12 years ago that could generate just about any sensor signal so you could see what it normally looked like, but you could learn the same thing from any text book. Not many shops bought them because of their limited value. They could have actually been of more value to a school, but in my classes we never needed to know all those details, partly because we weren't going to make a diagnosis that way, and partly because the computer is already checking those signals, and it will tell us when there is a problem with that circuit.

I forgot to mention last night that in most applications you're going to find some kind of metal disc with multiple groups of notches that are detected by the crankshaft position sensor. On some Chrysler products, for example, there will be three sets of four notches for a V-6 engine, but those only tell the computer when a pair of pistons are coming up on top dead center. You also need pulses from the camshaft position sensor to tell it which two pistons are coming up on top dead center. On other models, there could be four notches, four notches, then three notches. With the three notches, the computer figures out when piston number one is coming up on top dead center. Those systems use ignition coil packs that have one coil to fire two cylinders at the same time, one on the compression stroke, and the "waste spark" on the other cylinder on its exhaust stroke. You don't need a camshaft position sensor when the engine uses a distributor because the distributor decides which one cylinder is going to get the next spark.

The point of this sad story is when rotating the crankshaft by hand, those notches are pretty far apart, so this is a lot of work to see if the signal voltage changes. When we experiment this way with reading signals, we're more likely to do it with anti-lock brake wheel speed sensors. Those develop around 45 to 60 pulses per revolution so it's easy to read something, but here again, the exact voltage is irrelevant. Digital voltmeters are only accurate on the AC Volts scales when reading a 60 hertz sine wave. They are totally inaccurate at other frequencies, and the voltage of the signals depends on wheel speed, just like with other magnetic sensors and generators. Also, when these position sensors have three wires, meaning there's a bunch of electronic circuitry inside them, they develop square=wave signals. Digital meters do not like anything other than nice smooth sine waves. The only meters that hold any value are those that can read frequency, but that still has no meaning unless you can read all four wheels at the same time with four meters. That is what the computer does, and we can see that with a scanner. The only value in testing the signal with a meter is to know whether you have something or nothing. When you have something, there is still a lot more the computer checks for to know when to set a fault code.

To get back to your original problem, one thing I forgot to mention is for some of these magnetic sensors, the air gap can be critical. When you have multiple repeat failures, it could just be bad luck with one replacement brand, or you may need to look for a mechanical issue related to that sensor. Examples of mechanical problems include that air gap, or a broken tone ring or whatever metal piece the sensor is detecting. Most crankshaft position sensors have a type of mounting bracket that you just bolt on and you're done. A few have slotted mounting holes to allow for adjustment. When you see those slotted holes, there is a procedure to set that air gap. I had a dozen that I was too smart to have to follow that procedure. The 13th one came back on a tow truck two weeks later with a fault code for that sensor, and a crank / no-start condition. I replaced the sensor, but setting the air gap as instructed probably would have solved the problem. So much for being smarter than the engineers.

If I can jump in here, did you use a AC Delco sensor? if not that might be the problem, aftermarket sensors are not as good and fail. Here is the sensor location in case someone that visits this post can understand what we are talking about. Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Ken, yes both sensors I've tried are AC Delco brand. The first was a #12627185 (same as the original the car came with) and it failed after 19 days. Then I read this sensor model was discontinued and replaced by #12674702, so this is what is in the car now. So far so good but it's only been a day. I'll keep you posted if this fails also or not.

Hello, if I change the crankshaft position sensor for my car listed above, do I have to do the relearning or I can ignore relearning?

Thanks.

Please do, we are interested to see what it is.

It must be reset using a scan tool or it will set a code P0315. What is the reason you are replacing the sensor? If the engine runs and has not set a misfire code or is stalling when it heats up it may not be the sensor that is the issue.

Hello Steve, the whole story can be found here:

https://www.2carpros.com/questions/cranks-but-doesnt-start-randomly-happens/r/991663087

Intermittent faults could be the sensor or the wiring to it. Because it's an easy part to get to I'd change it out and check the connector real good.

I'd just like to find the easiest way to get to the crankshaft position sensor. I think I need to remove the starter but a diagram would be helpful. Is it possible to remove the throttle body and access it from above?

Hello, I'm Danny.

Yes, you have to remove the starter motor to have better access. Here is a tutorial showing what is involved for a crankshaft position sensor:

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

I've attached picture replacement steps below for your car. Hope this helps and thanks for using 2CarPros.

Hi, my question is how to test crankshaft position sensor with a multimeter and where is it?

You just measure the resistance across the terminals on the sensor with it unplugged.Typically you would see around 800-1200 ohms Whey they fail they wont read a resistance value they will read as a open.

Here is the location of the crankshaft sensor and instructions on how to replace it in the diagrams below. I found both engines.

Crankshaft Position System Variation Learn

Note: The crankshaft position (CKP) system variation learn procedure is required when the following service procedures have been performed, regardless of whether DTC P0315 is set:

* Engine replacement
* Engine control module (ECM) replacement
* Crankshaft damper replacement
* Crankshaft replacement
* CKP sensor replacement
* Any engine repairs which disturb the crankshaft to CKP sensor relationship

Note: The scan tool monitors certain component signals to determine if all the conditions are met to continue with the CKP system variation learn procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:

* CKP sensor activity-If there is a CKP sensor condition, refer to the applicable DTC that set.
* Camshaft position (CMP) signal activity-If there is a CMP signal condition, refer to the applicable DTC that set.
* Engine coolant temperature (ECT)-If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.

1. Install a scan tool.
2. Monitor the ECM for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle) for the applicable DTC that set.
3. With a scan tool, select the CKP system variation learn procedure and perform the following:

1. Observe the fuel cut-off for the applicable engine.
2. Block the drive wheels.
3. Set the parking brake.
4. Place the vehicle's transmission in Park or Neutral.
5. Turn the air conditioning (A/C) OFF.
6. Cycle the ignition from OFF to ON.
7. Apply and hold the brake pedal for the duration of the procedure.
8. Start and idle the engine.
9. Accelerate to wide open throttle (WOT). The engine should not accelerate beyond the calibrated fuel cut-off RPM value noted in step 3.1. Release the throttle immediately if the value is exceeded.

Note: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

10. Release the throttle when fuel cut-off occurs.

4. The scan tool displays Learn Status: Learned this Ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315 (See: A L L Diagnostic Trouble Codes ( DTC ) > P Code Charts > Powertrain Management). If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle) for the applicable DTC that set.
5. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.


Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

thanks but how can I test the sensor with a multimeter? I dont know how

Sorry here is a guide to help you

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Those had a coil of wire wrapped around a magnet. It's that coil you would read the continuity of with your ohm meter meter.

With the newer three-wire sensors, that coil of wire can still be used, but you can't get to any test points to measure it. Most crankshaft position sensors and camshaft position sensors use "Hall Effect" transistors. Those turn on and off in the presence of a magnetic field. In this case, they have their own internal magnets, and a notch or a finger of a metal "pole piece" moving by disturbs its magnetic field. That change in the magnetic field is what turns the transistor on and off. That switching transistor turns circuitry in the sensor on and off. Because of that circuitry, there is no way to test one of these sensors with an ohm meter.

If you want to get really carried away, you can buy an expensive digital meter that measures frequency, but even most mechanics never do that. Your meter measures AC voltage, but it is only accurate when measuring a 60 Hz sine wave, meaning house current. Crankshaft position sensor signals are square waves, and never at 60 Hz. Your meter will likely not read the signal, even if the sensor is working.

You might get some indication on the DC scale, but I wouldn't even know for sure what to expect. Most position sensor signals switch instantly between 0.0 volts and 5.0 volts. During engine cranking, the voltage would change much faster than as often as the meter takes a new reading and displays it. At most all you'd see is random numbers bouncing around that wouldn't mean anything. If you were real lucky, you might see the change between 0.0 and 5.0 volts if you rotated the engine slowly by hand. Some sensors don't generate a signal until their magnetic fields are disturbed more quickly, as in cranking speed, so you still would not have any information of value.

The place to start is by reading and recording the diagnostic fault codes. Codes for position sensors don't always set right away, but if you do get a code related to the cam or crank sensor, understand those codes never ever say to replace a part or that one is bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. First you have to rule out connector terminal and wiring problems, and mechanical problems associated with that code. In the case of a crankshaft position sensor code, there is probably a 75 percent chance a code is caused by the sensor, but you also must consider the air gap, (on engines where that is adjustable and critical), and whatever moving parts triggers those signals.

thanks for helping me, it was the sensor I love this site.

I want to say thank you for all the information. This made me register for this site. I am taking on a project of a 2009 Chevy Silverado 4.8l WT. I get the feeling this site will help alot.

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