TEST 1: Verifying The Cam Signal
To test the cam sensor, you're gonna' have to tap into its two wires with your multimeter.
These two wires are the DK GRN (dark green) wire and the LT BLU (light blue) wire of the sensor's harness connector.
The purpose of tapping into these two wires is to see if your multimeter can confirm that the camshaft position sensor is working and creating a fluctuating AC voltage signal.
To be a bit more specific, this AC voltage signal should fluctuate below and above 1 volt AC while the engine is cranking or running.
IMPORTANT: Make sure that the multimeter test lead wires don't get caught in the serpenting belt (when you crank the engine) or you'll damage the multimeter test leads and/or the multimeter.
Alright, these are the test steps:
Disconnect the cam sensor's electrical connector and remove some of the plastic wire loom protector and/or the black electrical tape that shields/protects the two wires of the cam sensor.
Reconnect the connector to the cam sensor now and place your multimeter in Volts AC mode.
Using a wire-piercing probe or another appropriate tool, probe the number 1 and number 2 wires of the cam sensor with the multimeter test leads.
To see what a what wire piercing probe tool looks like, click here: Wire Piercing Probe.
It doesn't matter which multimeter test lead (RED or BLACK) goes where, since the polarity of the leads doesn't matter.
When everything has been set up and you're a safe distance from the engine, have your helper crank the engine as you observe the multimeter's AC Volts readings.
If the camshaft position sensor is working correctly, the multimeter will register an an oscillating voltage between 0.5 to 1 Volt AC.
Now, to be a bit more specific: your multimeter will not register a steady AC voltage. Instead, the reading will jump between 0.5 Volts AC to a bit above 1 Volt AC continually as the engine is cranking and only when the engine is cranking.
Alright, let's find out if you have a bad cam sensor on your hands or not. Choose from the CASES below that best match your specific results:
CASE 1: The multimeter registered the indicated AC voltage with the engine cranking. This result indicates that the camshaft position sensor is creating a good cam signal and is working fine.
If you have confirmed that the camshaft position sensor is OK but your Ford's powertrain control module (PCM) is still lighting up the check engine light with a cam sensor trouble code, then there's a good chance that there's an open or a short in one of the two cam sensor circuits.
Although it's beyond the scope of this tutorial, your next step is to check the continuity of the cam sensor wires between the cam sensor connector and the PCM connector.
CASE 2: The multimeter DID NOT register the indicated AC voltage with the engine cranking: This confirms that the camshaft position sensor is fried and needs to be replaced.
If you'd like to buy the factory original Motorcraft cam sensor (and save), check out the section: Where To Buy The Cam Sensor And Save.
Typical Location Of The Cam Sensor
More Ford 4.6L, 5.4L Tutorials
To see all of the Ford 4.6L, 5.4L diagnostic tutorials, check out this index: Ford 4.6L, 5.4L Index Of Articles.
Here's a sample of the troubleshooting tutorials you'll find in the index:
- How Can I Tell What's Wrong With My Transmission? (Ford 4.6L, 5.4L)
- How To Diagnose Misfire Codes P0300-P0308 (Ford 4.6L, 5.4L).
- How To Test Ford 4.6L, 5.4L Coil-On-Plug Ignition Coils (at: easyautodiagnostics.com).
- How To Test The Ford MAF (4.2L, 4.6L, 5.4L) (at: easyautodiagnostics.com).
- How to test the 4.6L, 5.4L Throttle Position Sensor (TPS) (at: easyautodiagnostics.com).
If this info saved the day, buy me a beer!