How To Test a Eclipse Cam Sensor

How To Test a Eclipse Cam Sensor


The Eclipse cam sensor in your 2.0 liter non turbo Mitsubishi is an important part of EFI system. This three pin hall effect sensor is there to read the positioning and movement of your 420A camshaft. By picking up the cogs and rotation of your camshaft, your Mitsubishi engine computer can accurately control the spark events.

When this sensor goes bad, one of the earliest signs of trouble will be your Eclipse check engine light. Today I’ll be showing you how to test your Eclipse cam sensor in a 1999 Mitsubishi with the non turbo 420A engine in it. This DIY article will show you how to measure the sensor to ensure proper operation. Keep in mind that although this test is for the non turbo version of the Eclipse, the 2.4 liter SOHC 4G64 engine in the non turbo Eclipse Spyder is not the same.

test Mitsubishi Eclipse cam sensor DIY 1If you own a turbo 4G63 engine, the cam angle sensor is vastly different than the one used in this test. If you haven’t already checked out our 1G CAS in a 2G writeup, check it out here in our How To Guide.

The Eclipse cam sensor is also known as the cam angle sensor, the CAS or CMP sensor. Locate the three pin Eclipse cam sensor on the side of your cylinder head to begin testing. In order to complete this testing guide, you will need to use a digital multimeter.


Using your multimeter you will be testing the CAS in your 2G non turbo Eclipse. This is done by turning the Eclipse ignition to the ON position in your DSM, and checking the CAS wiring connector.

The first part of our How To Guide will be checking for power and ground circuits at your Eclipse cam sensor.

To do this turn the dial of your multimeter to read DC voltage, and locate your cam angle sensor. Disconnect the three pin harness, and you will place the black lead of your multimeter to the negative battery terminal.

Testing the Eclipse cam sensor for power

Now you will be using the red lead to gently probe the front of your cam sensor harness. Never force the lead into the harness otherwise you run the risk of damaging your cam sensor connector.

Use the 2G Eclipse cam sensor wiring diagram below to reference the wire that leads to PIN A. This is the power wire and with your ignition turned to the ON position, you should have 8 volts of power here. Remember that you are testing the ENGINE side of the harness.

Eclipse Cam Sensor

Once you have determined that you have power at this wire, you can check for a ground signal.

This wire is the one that leads to PIN B, and should have a ground that’s sent by your Eclipse ECU.

If you have both power and ground at these wires, your Eclipse cam sensor should be working properly.

The next part of the DIY tutorial is to test the cam sensor signal. This wire is the one that leads to PIN C in our Eclipse cam sensor wiring diagram. The next part of our test will require you to manually rotate your engine, so it may be best to remove your spark plugs and ignition wires.

Testing the Eclipse cam sensor signal

To perform this last part of our 2G Eclipse cam angle sensor test, you will need a 1/2 inch ratchet. Disconnect the coil packs that are mounted to the top of your engine by unplugging the engine harness. You may need to remove the passenger side tire to access the crankshaft pulley and the bolt that runs through it.

test Mitsubishi Eclipse cam sensor DIY 2

You may also need to jack up the front of your Eclipse to get better access to the front of your 420A engine. When doing so make sure to always use jackstands and to properly engage your parking brake.

Once you have the ignition coils disconnected and your spark plugs removed, your 420A engine should not have compression making it easier for you to rotate your engine. Reconnect the Eclipse cam sensor harness and you will need to pierce the wire that leads to PIN C. Once you have the the multimeter in place, you will rotate your non turbo 2.0 liter engine, while monitoring the voltage from the cam angle sensor.

Place the black lead of your multimeter on the negative battery terminal, and measure the wire leading to PIN C. Remember that your Eclipse cam sensor should be plugged in for this last leg of our test.

Now manually rotate your 420A engine using your 1/2 ratchet. Monitor the voltage from your CAS, which should switch between 5 volts and between 0.3 to 0.5 volts of signal. Remember that this signal should switch between the two values and should now sweep or scale to any voltage. The switching signal means that your cam sensor is reading the cogs on your camshaft properly.

If your Eclipse cam sensor does not respond accordingly, it’s died and gone to Eclipse sensor heaven. Remove the two bolts that secure the cam sensor in place, and install your new replacement CAS sensor. After you’ve replaced your Eclipse cam sensor, use the right OBDII scan tool to clear any stored DTC trouble codes.

Have any questions about our Eclipse cam sensor guide? Leave us a question below and let us know!