Circuit/System Description

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The engine control module (ECM) uses the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor pulses to monitor the correlation between the crankshaft and the camshaft position. The crankshaft reluctor wheel consists of a 60-tooth pattern with 2 teeth missing for the reference gap. Each tooth is evenly spaced 6 degrees apart, except for the reference gap. The camshaft reluctor wheel has 4 teeth, 2 narrow, and 2 wide. The 4 trailing edges of each tooth are evenly spaced at 90 degrees apart around the circumference of the camshaft sprocket. With the engine running, and the CMP actuator in the parked position, the ECM expects the camshaft signal pulses to occur 36 crankshaft degrees before top dead center (BTDC) for cylinder number 1, and every 90 degrees thereafter.