ICM And CKP/CMP Sensor Circuit Wiring Diagram (2001-2002 3.8L V6 Buick LeSabre)

APPLIES TO: This ignition control module (ICM), CKP and CMP sensor circuit wiring diagram applies to the following vehicles:

• 3.8L V6 Buick LeSabre: 2001, 2002.

Ignition Control Module (ICM)

The ignition control module (ICM) is the component that manages the ignition system during cranking and works closely with the PCM after the engine starts. It powers the crankshaft position sensor, interprets the signals it produces, fires the ignition coils in the correct sequence, and sends engine speed and crankshaft position information to the PCM.

Without accurate crankshaft position signals, the ICM doesn't know when to fire the ignition coils. The result is usually a no-spark, cranks-but-doesn't-start condition.

Crankshaft Position (CKP) Sensor

The crankshaft position sensor contains two Hall-effect sensors inside one housing. As the crankshaft turns, interrupter rings mounted behind the harmonic balancer create two digital ON/OFF signals that the ignition control module constantly monitors.

The ICM uses these signals to determine both crankshaft position and engine speed. We've got to have both signals present for the ignition system to operate correctly, so a problem with either one can prevent the engine from starting.

CKP SENSOR TESTS: How To Test The CKP Sensor With A Multimeter (1994-2005 3.8L V6 Buick LeSabre).

Camshaft Position (CMP) Sensor

The camshaft position sensor lets the PCM know when cylinder #1 is on its power stroke. The PCM uses this information to synchronize sequential fuel injection for the best performance and fuel economy.

If the CMP signal is lost, the engine will usually still start and run using a backup strategy, although it'll often set a diagnostic trouble code like P0341.

One very common failure on these engines has nothing to do with the sensor itself. The small magnet attached to the camshaft sprocket is held in place by a plastic carrier that's known to crack and break with age. When the magnet falls off, the CMP sensor can't generate its signal, making it appear that the sensor has failed when the real problem is the missing magnet.