Saab 9-3 1999-2005
Saab 9-5 1999-2005
Saab 9-3 1999-2005
Saab 9-5 1999-2005
The Camshaft Position (CMP) Sensor is a permanent magnet output coil device that operates within a 5 volt DC reference range, and monitors the speed and position of the camshaft. A reluctor is attached directly to the camshaft, and is used to generate a digital signal as it passes the magnetic coil; the alternating lines of magnetic flux are used by the sensor to produce a digital pulse. The CMP signal is used by the Powertrain Control Module (PCM) to calculate ignition timing, firing order, fuel injector timing, and misfire diagnostics.
Removal & Installation
Ignition takes place with individual ignition coils placed on the respective spark plug. The spark plugs together with the ignition coils and Combustion Detection Module (CDM) are used to detect combustion and possible knocking. This means there is no need for a camshaft position sensor.2.3L Engine
- Before servicing the vehicle, refer to the precautions.
- Remove the upper engine cover and insulation.
Disconnect the crankcase ventilation pipe 2 screws and a hose clip and raise it slightly..
NOTEOn vehicles equipped with preheated crankcase ventilation, take care not to damage the heating circuit in the hose.
Unplug the position sensor connector.
WARNINGTake care when releasing the locking mechanism on the connector so as not to damage the connector. Pull the halves straight apart to avoid bending the pins. For further information regarding connectors, refer to Connectors, handling and inspection.
Remove the position sensor.
- Install the position sensor. Tighten to 7 ft. lbs. (9 Nm).
- Install the crankcase ventilation pipe.
- Plug in the position sensor.
- Install the insulation and the upper engine cover.
CMP Circuit Testing
Use a suitable scan tool or a Graphing Multi-Meter (GMM in order to view the CMP data.
CMP Sensor logic is based on alternating lines of magnetic flux which generate a digital ON/OFF signal to the PCM, and are based on the speed and position of the camshaft (See Figure 1).
Verify that the engine timing components (timing belt, timing chain, or timing gears) are properly installed, and that there is no foreign material obstructing the path between the reluctor and the CMP sensor. If any engine mechanical faults are evident, locate and repair as required before continuing.
A Digital Volt-Ohm Meter (DVOM) may be used to verify the condition of the wiring: additional information may be acquired by taking measurements at the sensor connector as well as the PCM connector. If significant resistance is measured (greater than 5 ohms) is measured, check the wiring harness and connections for corrosion, poor pin connections, or damaged wires.
If all engine wiring and pin connections are confirmed, disconnect the CMP Sensor to verify the signal with a GMM, and verify PCM communication before replacing the CMP Sensor.
The CMP Sensor provides a digital input signal (See Figure 1) to the Powertrain Control Module (PCM) for a number of engine control system calculations. The CMP signal is compared with the Crankshaft Position Sensor (CKP) and Vehicle Speed Sensor (VSS) for measured operating conditions, and the Pulse Width Modulation pattern is used by the Powertrain Control Module (PCM) to calculate ignition timing, firing order, fuel injector timing, and misfire diagnostics.
CMP Sensor feedback patterns vary according to the reluctor configuration and PCM logic. While most models use a single tooth for Top Dead Center (TDC), others may use multiple reluctor teeth for additional positions of camshaft rotation, which may include one per cylinder, or 0°,90°, 180°, and 270° respectively.Connection & Wiring Diagnosis
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.
Many intermittent open or short circuits may be caused by wiring harness and connector movement due to vibration, engine torque, bumps and rough pavement, etc.
Test the wiring harness and connectors by performing the following tests:
Move the related connectors and wiring while monitoring the appropriate scan tool data.
Test the connector terminal pins and/or wiring by performing the following tests:
Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body.