The camshaft position (CMP) sensor on the 1998-2003 2.2L Isuzu Rodeo or 1998-2000 2.2L Isuzu Amigo can easily be tested to see if it's good or bad. And it all can be done with just a multimeter. Yep, no scan tool required (although if you have one —awesome).
In this tutorial, I'm going to explain the three different tests you can perform on the CMP sensor while it's still on the vehicle to find out if it's functioning correctly or if it's toast and needs to be replaced.
The three things that we're going to be checking are the CMP sensor's voltage signal to the PCM, and then we'll make sure that it's getting power and Ground.
Contents of this tutorial:
- Symptoms Of A Bad CMP Sensor.
- Circuit Descriptions Of The Camshaft Position Sensor.
- Important Safety Precautions And Tips.
- TEST 1: Testing The CMP Signal.
- TEST 2: Making Sure The CMP Sensor Has Power.
- TEST 3: Making Sure The CMP Sensor Has Ground.
- More 2.2L Isuzu Rodeo And Amigo Diagnostic Tutorials.
APPLIES TO: This tutorial applies to the following vehicles:
- 2.2L Isuzu Amigo: 1998, 1999, 2000.
- 2.2L Isuzu Rodeo: 1998, 1999, 2000, 2001, 2002, 2003.
CMP SENSOR CIRCUIT WIRING DIAGRAM:
RELATED TUTORIALS: The following tutorial will help you test the ignition coil pack/ICM assembly and the CKP sensor:
- How To Test The CKP Sensor (1998-2003 2.2L Isuzu Rodeo, Amigo).
- How To Test The Ignition Coil Pack (1998-2003 2.2L Isuzu Rodeo, Amigo).
Symptoms Of A Bad CMP Sensor
The camshaft position (CMP) sensor sends the PCM a signal that tells it where the camshaft is positioned in relation to the crankshaft.
The PCM uses this signal as a synchronization pulse to identify the number-one piston during its power stroke. This information allows the PCM to control the fuel injectors in the correct sequence and operate the engine in true sequential fuel-injection mode.
If the PCM detects an incorrect or missing CMP signal, it's gonna' set one or more of the following diagnostic trouble codes:
- P0341: Camshaft Position Sensor Performance or Incorrect Signal.
- P0342: Camshaft Position Sensor Low Input or Lost Signal.
When the CMP signal is lost while the engine is running, the PCM switches to a calculated sequential fuel-injection strategy based on the last injector pulse it received. The engine will continue running, although the check engine light will usually come on and a CMP sensor trouble code will be stored.
You may notice one or more of the following symptoms:
- Check engine light: The PCM may store a P0341 or P0342 CMP sensor trouble code.
- Hard starting: The engine may take longer than normal to start if the PCM isn't receiving a valid synchronization signal.
- Rough or uneven running: An incorrect or unstable CMP signal can affect injector synchronization and engine operation.
- Reduced performance or fuel economy: The engine may continue running in its calculated fuel-injection mode, but it may not operate as efficiently.
Circuit Descriptions Of The Camshaft Position Sensor
The CMP sensor on your 2.2L Isuzu Rodeo or Amigo is a 3-wire Hall-effect sensor. To produce a camshaft position signal, it needs a 12-Volt power supply and a good Ground.
The PCM provides a voltage on the signal circuit. As the camshaft rotates, the CMP sensor switches this circuit between its high state and Ground, producing the digital signal the PCM uses for injector synchronization.
NOTE: The CMP sensor has male terminals, while the engine wiring harness connector has female terminals.
The following table identifies each female terminal of the CMP sensor connector:
| CMP Sensor Connector | ||
|---|---|---|
| Terminal | Wire Color | Description |
| 1 | Blue (BLU) | CMP Signal Output to PCM |
| 2 | Black with blue stripe (BLK/BLU) | Chassis Ground |
| 3 | Black with yellow stripe (BLK/YEL) | 12-Volt Power Supply |
WIRING DIAGRAMS: You can find the camshaft position (CMP) sensor circuit wiring diagram here:
Important Safety Precautions And Tips
TIP 1: All of the CMP sensor tests I'm going to show you in this tutorial are performed with the sensor installed on the engine. There's no need to remove it from the engine to test it.
TIP 2: You'll need to rotate the engine by hand to check the CMP sensor's signal output with a multimeter.
If you use the starter motor, the engine will turn too quickly and your multimeter will probably display an average voltage instead of the individual ON/OFF signal pulses.
To manually turn the engine over, use a ratchet and the appropriate socket on the crankshaft pulley bolt.
TEST 1: Testing The CMP Signal
To begin our CMP sensor diagnostic, we're going to check its output signal to see if it's switching between an ON and OFF state.
To be a bit more specific: We're going to slowly rotate the engine and see if our multimeter alternates between these two readings:
- ON: The CMP signal rises to approximately 4 Volts DC.
- OFF: The signal drops to approximately 0 Volts DC.
If the CMP sensor has failed, its output signal (on the blue wire) is gonna stay stuck at one voltage as we rotate the engine (instead of alternating between 0 and 4 Volts).
IMPORTANT: The CMP sensor must remain connected to its engine wiring harness connector for this test to work. You'll need to connect your multimeter test lead using a back probe or wire-piercing probe so you can read the signal without disconnecting the sensor: Goupchn 4mm Banana to Banana Plug Test Leads Kit (Amazon affiliate link).
NOTE: Don't have a multimeter or need to upgrade yours? Check out my recommendation: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (Amazon affiliate link).
These are the test steps:
- 1
Disconnect the ignition coil pack from its 4-wire connector.
NOTE: This is an important safety precaution that'll keep the engine from starting. - 2
Place your multimeter in Volts DC mode.
- 3
Connect the black multimeter test lead to the battery negative (-) terminal.
- 4
Connect the red multimeter test lead to the blue (BLU) wire of the CMP sensor connector.
The blue wire is located on the engine wiring harness side of the connector.
NOTE: The CMP sensor must remain connected to its engine wiring harness connector so you can read its signal. - 5
Turn the ignition key to the ON position, but don't crank or start the engine.
- 6
Slowly turn the engine by hand using a 1/2-inch ratchet and the appropriate socket on the camshaft pulley bolt. For an accurate test, don't use the starter motor.
- 7
Your multimeter should display an ON/OFF voltage as you turn the engine.
ON is when the multimeter reads approximately 5 Volts DC, and OFF is when it reads approximately 0 Volts DC.
Let's examine your CMP signal test result:
CASE 1: The CMP sensor is producing the indicated ON/OFF DC voltage. This is the correct test result. Since the CMP sensor is producing a proper switching signal, we know that it's functioning correctly and is receiving both power and Ground.
No further CMP sensor testing is needed. The sensor itself is working properly.
CASE 2: The CMP sensor is not producing the indicated ON/OFF DC voltage. This test result usually means that the CMP sensor is defective. But before you head out to buy one, we need to make sure it's receiving both power and Ground.
If either one of these is missing, the sensor won't be able to produce a CMP signal. So, our next step is to verify that the sensor is receiving its 12-Volt power supply. For this test, head over to: TEST 2: Making Sure The CMP Sensor Has Power.
TEST 2: Making Sure The CMP Sensor Has Power
So far, you've confirmed that the CMP sensor isn't producing an on-off voltage signal (TEST 1).
Our next step is to confirm that the black with yellow stripe (BLK/YEL) wire of the CMP sensor's 3-wire connector is delivering 10 to 12 volts to the sensor.
If our test confirms the sensor is getting supplied with power, then we'll head over to TEST 3 and make sure that it's getting ground.
NOTE: Be careful not to spread or damage the female terminal in the engine wiring harness connector when probing it with your multimeter lead.
IMPORTANT: This test is performed on the engine wiring harness connector, not on the CMP sensor itself. The engine wiring harness connector contains the female terminals.
These are the test steps:
- 1
Disconnect the CMP sensor from its connector.
- 2
Place your multimeter in Volts DC mode.
- 3
Connect the black multimeter test lead to the negative (-) battery terminal.
- 4
Turn the key to the ON position, but don't crank or start the engine.
- 5
Gently probe female terminal 3 of the engine wiring harness connector.
Confirm that terminal 3 connects to the black with yellow stripe (BLK/YEL) 12-Volt power wire.
NOTE: This test is performed on the engine wiring harness connector, which contains the female terminals. - 6
Your multimeter should read 10 to 12 Volts DC.
Let's examine your test result:
CASE 1: The CMP sensor is receiving 10 to 12 Volts DC. This is the correct result and confirms that the sensor is getting power.
Our next and final circuit test is to verify that the CMP sensor has a good Ground. For that test, go to: TEST 3: Making Sure The CMP Sensor Has Ground.
CASE 2: The CMP sensor is not receiving the indicated voltage. Without this power supply, the CMP sensor cannot produce its switching signal.
The missing voltage may be caused by an open-circuit problem in the black with yellow stripe (BLK/YEL) wire, a loose or damaged connector terminal, a blown ENGINE IGN fuse, or another problem in the ignition-power circuit.
Although tracing this power-supply problem is beyond the scope of this tutorial, the next step is to determine why the 12 Volts is missing and repair the circuit before replacing the CMP sensor.
TEST 3: Making Sure The CMP Sensor Has Ground
If you've reached this point, your CMP sensor test results indicate:
- The CMP sensor isn't generating an ON/OFF signal (TEST 1).
- The CMP sensor is getting power from the BLK/YEL wire (TEST 2).
That leaves us with one final circuit to check: the CMP sensor's Ground, which is delivered to the CMP sensor by the black with blue stripe (BLK/BLU) wire.
The BLK/BLU wire delivers a chassis Ground to female terminal 2 of the CMP sensor's 3-wire connector.
We're gonna' verify this chassis Ground with a simple multimeter voltage test (the same basic type of test we used in TEST 2 to confirm the sensor's 12-Volt power supply).
NOTE: Be very careful not to spread or damage the female terminal in the connector with your multimeter test lead.
IMPORTANT: This test is performed on the engine wiring harness connector, not on the CMP sensor itself. The engine wiring harness connector has female terminals.
These are the test steps:
- 1
Disconnect the CMP sensor from its connector.
- 2
Place your multimeter in Volts DC mode.
- 3
Connect the red multimeter test lead to the positive (+) battery terminal.
- 4
Gently probe female terminal 2 of the connector.
Confirm that terminal 2 connects to the black with a blue stripe (BLK/BLU) wire of the 3-wire connector.
NOTE: This test is performed on the engine wiring harness connector, which has female terminals. - 5
Your multimeter should report 10 to 12 Volts DC if the BLK/YEL wire is connected to chassis Ground.
NOTE: This is a chassis Ground, as such, it should be present at all times regardless of key position.
Let's take a look at what your test results mean:
CASE 1: Ground is present. This is the correct test result and confirms the CMP sensor is getting Ground.
We can conclude the CMP (CMP) sensor is toast and needs to be replaced if you have checked and confirmed:
- The CMP sensor is not producing an ON/OFF signal (TEST 1).
- The CMP sensor is getting 10 to 12 Volts DC from its BLK/YEL wire (TEST 2).
- The CMP sensor is getting Ground from its BLK/BLU wire (this test).
IMPORTANT: If you replace the CMP sensor, the PCM must complete the Tooth Error Correction procedure with a scan tool.
CASE 2: Ground is not present. Without Ground, the CMP sensor will not produce its ON/OFF signal.
The most likely cause of the missing Ground is an open-circuit problem in the BLK/BLU wire between the CMP sensor connector and its chassis Ground connection.
Although troubleshooting this missing Ground is beyond the scope of this tutorial, your next step is to find out why the Ground is missing and restore the circuit.
More 2.2L Isuzu Rodeo And Amigo Diagnostic Tutorials
You can find a complete list of diagnostics tutorials for your 2.2L Isuzu Rodeo and Amigo in this index:
Here's a small sample of the tutorials you'll find:
- How To Test Engine Compression (1998-2003 2.2L Isuzu Amigo And Rodeo).
- How To Test For A Blown Head Gasket (1998-2003 2.2L Isuzu Amigo And Rodeo).
- How To Test The TPS (1998-2003 2.2L Isuzu Amigo And Rodeo).
- How To Test The Fuel Pump (1998-2003 2.2L Isuzu Rodeo, Amigo).
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