How to Test a Harley Crank Position Sensor
A Harley-Davidson motorcycle engine may sputter and hesitate when a crank position sensor (CKP) starts to fail. The CKP sends data to the motorcycle computer data center about the position and speed of the crankshaft, the ignition and fuel injection. A malfunctioning CKP can cause the engine to backfire due to unburned fuel and hesitate when accelerating. The symptoms of a faulty CKP worsen when the bike is revved up. Contaminated fuel or bad spark plugs can also cause similar problems, so you may need to test the crank position sensor.
Turn the key in the ignition to the "Off" position. Turn the "Run/Stop" switch to "Run." Push and hold the odometer "Reset" button. Hold the "Reset" button and do not release it yet.
Turn the key to "Ignition," but don't start the engine. Release the odometer "Reset" button. Wait for the odometer to indicate the bike is in diagnostic mode by displaying "Diag." Push the odometer reset button and then release it when you see the "P" in the menu selection flashing.
Wait for the bike to complete the diagnostic of the electronic control module and the ignition control module. Write down the codes that are displayed after the diagnostic is complete. Code PO 374 indicates a failed or faulty crank position sensor due to a synchronization error.