If you suspect the crankshaft position (CKP) sensor is causing your 1.8L Nissan Sentra not to start, this tutorial will help you diagnose it using just a multimeter.
This multimeter test is a very accurate test that'll tell you if the crankshaft position sensor is good or bad.
Contents of this tutorial:
- Symptoms Of A Defective Crankshaft Position Sensor.
- Circuit Descriptions Of The Crankshaft Position Sensor.
- Where To Buy The Crankshaft Position Sensor.
- TEST 1: Checking The Crankshaft Position Signal With A Multimeter.
- TEST 2: Making Sure The CKP Sensor Is Getting Power.
- TEST 3: Making Sure The CKP Sensor Is Getting Ground.
- More 1.8L Nissan Sentra Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El Sensor CKP (2000-2002 1.8L Nissan Sentra) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 1.8L Nissan Sentra: 2000, 2001, 2002.
NOTE: If you need to test the camshaft position sensor, you can find the tutorial here: How To Test The Camshaft Position Sensor (2000-2002 1.8L Nissan Sentra).
Symptoms Of A Defective Crankshaft Position Sensor
Here's a basic list of the symptoms you'll see if the crankshaft position sensor fails on your 2000, 2001 or 2002 1.8L Nissan Sentra.
- The check engine light is illuminated with the following diagnostic trouble code:
- P0340:Crankshaft Position Sensor A Circuit
- The engine cranks but does not start.
- The fuel injection computer does not activate the fuel injectors (this is verified with a Noid light test).
- The fuel injection computer does not activate the ignition coils (this is verified with a spark tester).
- The fuel pump activates and sends the correct fuel pressure to the fuel injectors (this is verified with a fuel pressure gauge).
Circuit Descriptions Of The Crankshaft Position Sensor
The crankshaft position (CKP) sensor is located behind the engine. To be more precise: It's located directly under the starter motor.
To gain access to the CKP sensor electrical connector, you must remove the mass airflow sensor and intake air hose assembly.
Once you get to the CKP sensor connector, you'll notice three wires sticking out of it. Each wire has a specific role and the following table provides a brief description of each:
|CKP Sensor (2000, 2001, 2002 1.8L Nissan Sentra)|
|2||Red (RED)||Crankshaft Position Signal|
|3||white (WHT)||Power -12 Volts|
Where To Buy The Crankshaft Position Sensor
You can buy the crankshaft position sensor at your local auto parts store, or if like me, you want to save money on any type of purchase, you can buy it online.
The Hitachi CPS0001 Crankshaft Position Sensor listed below is the genuine factory part for the 2000-2002 1.8L Nissan Sentra.
You can check it out here:
TEST 1: Checking The Crankshaft Position Signal With A Multimeter
First of all, we'll make sure that the crankshaft position sensor is generating a signal.
Now to get into the details, the crankshaft position sensor generates an ON/OFF voltage that you and I can measure in Volts DC with a multimeter.
When the sensor is switched 'ON', it generates a voltage between 9 and 10 Volts DC. When the sensor is 'OFF', the voltage drops to 0 Volts DC.
The most common thing I've seen when the crankshaft sensor fails is that it gets stuck producing 9 to 10 Volts without ever dropping to zero Volts (as the engine is cranked manually from the crankshaft pulley).
So in this test section, we'll hook up a multimeter to the red wire on the CKP sensor connector, and then manually crank the engine and see if the sensor is generating its signal.
OK, let's get started:
Raise the front passenger side of your Sentra onto a jack stand (for safety).
Remove the front passenger side wheel and remove the plastic water splash guard (shield) that protects the crankshaft pulley and serpentine belt from water.
Disconnect the CKP sensor from its electrical connector.
IMPORTANT: For safety reasons, disconnect all ignition coils from their electrical connectors.
NOTE: To gain access to the CKP sensor connector, remove the air cleaner assembly and intake duct assembly (it's easier to access the connector from the top of the engine than from the bottom).
Connect the red multimeter test lead to the red wire of the CKP sensor connector.
You'll need to use a tool like a wire piercing probe to connect the red test lead to the red wire.
You can see a what a wire piercing probe looks like here: Wire Piercing Probe.
Reconnect the connector to the CKP sensor.
NOTE: For this test to work, the CKP sensor must be connected to its electrical connector.
Set your multimeter to Volts DC mode.
Connect the black multimeter test lead directly to the battery negative (-) terminal.
Once you have the multimeter set up, slowly turn the crankshaft pulley clockwise by hand while keeping an eye on the multimeter.
NOTE: Don't use the starter motor to crank the engine! I want to stress that you should turn the crankshaft pulley slowly.
The multimeter should register an ON/OFF voltage of 9-10 and 0 Volts as you turn the crankshaft pulley manually.
OFF is when the multimeter displays 9.5 - 10 Volts. ON is 0 Volts.
To be a little more specific, your multimeter will register 9 to 10 Volts most of the time you're turning the crankshaft pulley. When the CKP sensor is activated (and functioning correctly) by the pole piece on the crankshaft, this voltage drops to 0 Volts.
Let's take a look at what your test results mean:
CASE 1: The multimeter registered an ON/OFF voltage of 9-10 and 0 Volts as you manually turned the crankshaft pulley. This is the correct and expected test result and indicates that the crankshaft position sensor is working correctly.
CASE 2: The multimeter DID NOT register an ON/OFF voltage of 9-10 and 0 Volts as you manually turned the crankshaft pulley. This result indicates that the crankshaft position sensor is not generating a signal.
Before we condemn the sensor as defective, we need to make sure it's getting power and Ground. For the next test, go to: TEST 2: Making Sure The CKP Sensor Is Getting Power.