Lotus 2004 ELISE Service Notes page 165

Lotus Service Notes
Camshaft Lift Control (VVL)
P2646 A Rocker Arm Actuator System Performance or Stuck Off
P2647 A Rocker Arm Actuator System Stuck On
P2648 A Rocker Arm Actuator Control Circuit Low
P2649 A Rocker Arm Actuator Control Circuit High
Description
Intake and exhaust camshaft lift can be changed by means of the Variable Valve Lift (VVL) system, which varies
the amount of maximum lift of the intake and exhaust valves. The mechanism uses dual element rocker arms to
provide cam changeover, with both the intake and exhaust camshafts having high and low speed cam profiles.
The system is ECU controlled, using an oil control solenoid which, when activated, uses hydraulic pressure to
push a rocker arm locking pin into engagement to activate the high-speed cam profile. A signal from the VVL
oil pressure switch provides feedback to the ECU that VVL activation has taken place. VVL activation* to the
high lift camshaft profile occurs at 6200rpm when engine speed is increasing, and returns to the low lift camshaft
profile at 6000rpm when the engine speed is decreasing.
*Coolant temperature must be >60°C (140°F).
Component connections
Connector Description
1 Battery Voltage
2 VVL Oil Control Valve
- VVL Oil Pressure Switch
Monitor: Continuous
Enable Criteria: Engine running
Disable Criteria: None
Potential failure modes:
• VVL valve stuck open / closed
• VVL valve open circuit
• VVL valve short to ground
• Rocker arm failure
• Rocker shaft location pin failure
• ECU output circuit failure
Notes:
The MIL will be illuminated if the fault is present for 2 consecutive trips.
Page 42
sn_emp_cyclone.indd 42
P2646
P2647
P2648
P2649
ECU Pin ECU Connector
- -
12 (H3) 52 Way (Right)
21 (B2) 52 Way (Right)
Section EMP
'06 M.Y. in brackets
03/03/2006 11:03:40