Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Camshaft Actuator System Description: Notes
| Callout | Component Name |
|---|---|
| 1 | Camshaft Position (CMP) Sensor |
| 2 | Engine Coolant Temperature (ECT) Sensor |
| 3 | Camshaft Position (CMP) Actuator Solenoid Valve |
| 4 | Crankshaft Position (CKP) Sensor |
| 5 | CMP Actuator Assembly |
| 6 | Intake Camshaft |
| 7 | Exhaust Camshaft |
The camshaft position (CMP) actuator system enables the powertrain control module (PCM) to change camshaft timing while the engine is running. The CMP actuator assembly (5) varies camshaft position in response to directional changes in oil pressure. The CMP actuator solenoid valve controls the oil pressure that is applied to advance or retard the camshaft. Modifying camshaft timing under changing engine demand provides better balance between the following performance concerns:
- Engine power output
- Fuel economy
- Lower tailpipe emissions
The CMP actuator solenoid valve (3) is controlled by the PCM. The crankshaft position (CKP) sensor (4) and the CMP sensor (1) are used to monitor changes in camshaft position. The PCM uses information from the following sensors in order to calculate the desired camshaft position:
- The engine coolant temperature (ECT) sensor
- The mass air flow (MAF) sensor
- The throttle position (TP) sensor
- The vehicle speed sensor (VSS)
| Callout | Component Name |
|---|---|
| 1 | Lock Pin |
| 2 | Vane Wheel |
| 3 | Intake Camshaft |
| 4 | CMP Actuator Housing |
The CMP actuator assembly has an outer housing (4) that is driven by the engine timing chain. Inside the assembly is a wheel (2) with fixed vanes that is attached to the intake camshaft (3). The CMP actuator assembly also contains a lock pin (1) that prevents movement between the outer housing and the wheel vane assembly. The lock pin is released by oil pressure before any movement in the CMP actuator assembly takes place.
| Callout | Component Name |
|---|---|
| 1 | Spool Valve |
| 2 | Solenoid Plunger |
| 3 | Solenoid Coil |
| 4 | Oil Return During Retard |
| 5 | Oil Supply |
| 6 | Oil Return During Advance |
| 7 | Oil Supply to Camshaft Position Actuator for Advance |
| 8 | Oil Supply to Camshaft Position Actuator for Retard |
The CMP actuator solenoid valve directs the oil flow that controls the camshaft phase movement. The PCM commands the CMP solenoid to move the solenoid plunger (2) and spool valve (1) until oil flows from the advance passage (7) or the retard passage (8). In most operating conditions the opposite oil return passage is open at the same time as the oil supply passage.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.