How to Test 3 Wire Crank Sensor with Multimeter
Your vehicle has developed faults again and after checking all of the usual culprits, you can’t seem to find the problem.
You have an idea that, maybe, the problem could be from the engine.
Which component would you check? Well, one of them is the crankshaft which is one of the most important components to check out.
Thankfully, making a diagnosis on it isn’t a difficult procedure.
This article gives you the information you need to know about testing a crank sensor, including what this component is and the steps to make a diagnosis with a multimeter.
Let’s get right in.
What Is A Crankshaft Sensor
The crankshaft is a piece in a combustion engine that ensures it gets that rotational motion it needs to operate effectively.
A crank sensor, also known as the crankshaft position sensor or camshaft sensor, is a device used in a combustion engine to measure the position and speed of this crankshaft as it rotates.
By doing this, the crank sensor communicates with the engine control unit (ECU) and controls the level of fuel injection needed by the engine. It also dictates the timing of the engine ignition system.
This device is therefore a very important component in your vehicle and where there are faults with it, you would expect major problems. What are the problems you face from a bad crank sensor?
Symptoms Of A Bad Crank Sensor
Some of the pointers to a bad crank sensor include;
- Check Engine Indicator Illuminates
The engine icon on your dashboard indicates when there is a problem with your engine. If this light comes on, then you know that one of the components within your engine, like the crank sensor, is faulty.
You then check for these other hints
- Locked Gears
When you notice that your gears get stuck while you are trying to transmit from one to another, then the crankshaft sensor may have problems. A lot of times, the car has to be restarted before you can make this transmission.
You want to be careful if you experience this and get the problem solved as soon as possible.
- Difficulty Starting Vehicle
Of course, if the timing and volume of fuel injection are not as perfect as they need to be, your ignition system does not function properly.
- Repeated Stalling
The crank sensor also has a job to play when the vehicle is powered up and your car keeps on breaking down when the right amount of fuel isn’t injected into the engine.
- Acceleration Problems
A bad crankshaft comes with a lot of acceleration issues. Typically, if the device is bad, your acceleration is slow and limited, which could be dangerous. You may also experience your car jerking when you try to accelerate.
- Misfiring Engine
A bad crankshaft sensor means your fuel injector doesn’t function properly and could result in your engine misfiring.
Some other symptoms include increased fuel consumption due to inaccurate injections and an absence of fuel injector pulse.
These are not exclusive symptoms of a bad camshaft sensor but where a number of these exist, the device should be suspected.
Types Of Crank Sensors
Two common types of camshaft sensors exist. These are the inductive crank sensor and the hall-effect crank sensor. You know which is in your vehicle when you check the car manual.
The inductive crank sensor is also called a magnetic pick-up sensor and features two wires; the signal wire and the ground wire.
When testing this type of camshaft sensor, you use a multimeter to check for readings from the signal and ground wires. If you don’t get any, then the sensor has a problem.
The hall-effect crankshaft sensor features an additional wire; the reference volt wire. From this, you recognize that it is called the 3 wire crank sensor because it features three wires.
This category of sensors is what we are concerned with and a multimeter is the perfect functional tool to use to run a series of tests.
How To Test 3 Wire Crank Sensor With A Multimeter
To test a 3 wire crank sensor, you set your multimeter to DC voltage and use it to collect readings from the signal, reference, and ground wires. If the readings you obtain from these are not in coherence with indications contained in the car manual, then your crank sensor is bad.
This process goes deeper than this and would be explained further.
- Check Out The Position Of Wires
When making a diagnosis on your 3 wire crankshaft sensor with a multimeter, you have to separately test the signal and reference volt wire against the ground wire. Due to this, identifying which wire is which is crucial.
What you do here is to refer to your car’s manual. You locate and differentiate the wires within the crank sensor.
Nonetheless, these wires typically have common positions within the camshaft sensor and this video sheds a light.
- Test The Reference Volt Wire Against The Ground Wire
Once you differentiate the wires, you want to test whether any of them has faults. The first set you test is the reference volt wire and the ground wire.
What you do is set the multimeter to DC voltage and put your ignition switch in the “on” position without starting the engine. Connect the red (positive) lead to the reference volt wire and connect the black (negative) lead to the ground wire.
Your multimeter is expected to show a reading between 5 – 12 voltage, depending on the car and sensor you are using. If you don’t get any reading or your reading is inconsistent, then one of these wires could be faulty. It could also mean the entire camshaft sensor is faulty.
If your reading is okay, move on to the next step.
- Test The Signal Wire Against The Ground Wire
Now, you start up your engine, place the red (positive) lead on the signal wire, place the black (negative) lead on the ground wire, and then wait for a reading from your multimeter. The multimeter is expected to read about 5 volts.
If you don’t get any reading or the reading you get is inconsistent, then your camshaft sensor is bad and needs changing.
You can also check whether your ground wire is the culprit. You do this by disconnecting the camshaft connector, placing the black (negative) lead on the ground wire, and placing the red (positive) lead on your positive car battery terminal.
You’d expect to see a reading between 10 and 12 volts on the multimeter. If you don’t get this, then the fuel injector is not receiving enough ground to function properly.
Whether the problem is with your ground wire, signal wire, or reference volt wire, the whole device is required to be changed and this process could be quite tiring. Employing the service is an experience auto-mechanic is a great option for you.
Frequently Asked Questions
How Many Ohms Should A Crankshaft Sensor Have?
A crankshaft sensor is expected to have a resistance between 200 and 1000 ohms, depending on the value from the reference manual. If you don’t get a value in this range, then there is a short circuit or interruption in the sensor and it needs to be changed.
How Can You Tell If A Crank Sensor Is Bad?
Symptoms of a bad crank sensor include vehicle stalling, illuminated engine light, acceleration issues, transmission problems, and difficulty starting the vehicle.