ICM And 7X CKP Sensor Circuit Wiring Diagram (1998-2005 3.1L V6 Buick Century)

APPLIES TO: This ignition control module (ICM) and 7X CKP sensor circuit wiring diagram applies to the following vehicles:

• 3.1L V6 Buick Century: 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.

The 7X Crankshaft Position Sensor

The 7X CKP sensor is mounted on the rear side of the engine block, below the exhaust manifold and facing the firewall. It generates its signal by sensing the machined reluctor on the crankshaft.

The sensor's two wires connect directly to the ignition control module (ICM), where the AC voltage signal is processed. The sensor does not connect directly to the PCM.

During cranking, this signal allows the ignition control module to begin firing the ignition coils so the engine can start.

3X CKP SENSOR TESTS: How To Test The 7X Crankshaft Position Sensor (1994-2005 3.1L V6 Buick Century).

The Ignition Control Module (ICM)

The ignition control module is located beneath the three coil packs on top of the rear valve cover.

After processing the 7X CKP sensor signal, the ICM determines the correct coil firing sequence. It also sends a 3X crankshaft reference signal to the PCM.

The PCM uses this signal to determine engine RPM, synchronize fuel injector operation, and calculate spark advance. The 3X reference signal is a digital ON/OFF pulse that occurs three times per crankshaft revolution.

ICM DIAGNOSTIC TESTS: Testing The Ignition Module And Crank Sensor (GM 3.1L, 3.4L) (at: easyautodiagnostics.com).

Ignition Coils

This engine uses three individually mounted twin-tower ignition coils attached to the ignition control module. Each coil fires two spark plugs simultaneously in a waste-spark configuration.

Each ignition coil receives fused battery power on one side. The ignition control module controls the opposite side of the circuit by repeatedly switching the Ground path ON and OFF, causing the coil to generate high voltage for the spark plugs.

The two ignition coil failures I see most often are:

• Only one spark plug tower fires while the other tower remains dead.
• Both towers fail to produce spark because the ignition coil has failed completely.

Since each coil is a separate unit, you can replace only the failed ignition coil without replacing the others.

IGNITION COIL TESTS: How To Test The Ignition Coil Packs (GM 3.1L, 3.4L) (at: easyautodiagnostics.com).

Other 7X CKP Sensor Wiring Diagrams

• ICM And 3X CKP Sensor Circuit Wiring Diagram (1994-1995 3.1L V6 Buick Century).
• ICM And 7X CKP Sensor Circuit Wiring Diagram (1996 3.1L V6 Buick Century).
• ICM And 7X CKP Sensor Circuit Wiring Diagram (1997 3.1L V6 Buick Century).

More 3.1L V6 Buick Century Tutorials

You can find a complete list of 3.1L V6 Buick Century tutorials and wiring diagrams in this index:

• 3.1L V6 Buick Century Index of Articles.

Here's a sample of the tutorials you'll find in the index:

• How To Test The TPS With A Multimeter (1997-2005 3.1L V6 Buick Century).
• Common Causes Of Spark Plug Failure (1994-2005 3.1L V6 Buick Century).
• How To Test For A Blown Head Gasket (1994-2005 3.1L V6 Buick Century).
• How To Test Engine Compression (1994-2005 3.1L V6 Buick Century).