RAM 3500 HD Truck 2WD L6-6.7L DSL Turbo (2008)
Camshaft Position Sensor: Description and Operation
Operation
5.9L/6.7L DIESEL
The Camshaft Position Sensor (CMP) (1) contains a hall effect device. A rotating target wheel (tonewheel) for the CMP is located on the front timing
gear. This hall effect device detects notches located on the tonewheel. As the tonewheel rotates, the notches pass the tip of the CMP.
When the leading edge of the tonewheel notch passes the tip of the CMP, the following occurs: The interruption of magnetic field causes the voltage to
switch high resulting in a signal of approximately 5 volts.
When the trailing edge of the tonewheel notch passes the tip of the CMP, the following occurs: The change of the magnetic field causes the signal
voltage to switch low to 0 volts.
The CMP provides a signal to the Engine Control Module (ECM) at all times when the engine is running. The ECM uses the CMP information primarily
on engine start-up. Once the engine is running, the ECM uses the CMP as a backup sensor for engine speed. The Crankshaft Position Sensor (CKP) is
the primary engine speed indicator for the engine after the engine is running.
