P1D68

P1D68-CYLINDER 4 OIL SUPPLY SOLENOID VALVE PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

MultiAir is an electronically controlled variable intake valve phase and lift system. Unlike conventional intake valve phase and lift system which controls all the cylinder intake valves simultaneously and in the same proportion; MultiAir, through the use of an electronically controlled " hydraulic link" between the camshaft and intake valve, allow for each intake valve to be controlled independently. The valve lift and timing can be adjusted infinitely

The MultiAir valve train has a mechanical camshaft lobe acting on a hydraulic pump located between the camshaft intake lobe and the intake valve. The pump provides oil under pressure to a two-way electro-hydraulic solenoid valve called the Variable Valve Actuator (VVA) Solenoid. The VVA Solenoid is electronically controlled during the specific intake cam lobe event by the Powertrain Control Module (PCM). During the event the VVA Solenoid is commanded to either hold oil pressure or bleed oil. The Variable Valve Actuator (VVA) Solenoid is a normally open solenoid. The PCM provides 12 volts to close the solenoid. The position of the VVA Solenoid determines the intake valve timing and lift. This change on valve action is similar to creating a change in the camshaft lobe profile affecting lift and duration of the valve opening.

- When Monitored:
With the engine running and no battery or ASD Relay DTCs active.

- Set Condition:
The Powertrain Control Module (PCM) detects a short circuit condition between the VVA Solenoid Control return circuit and the VVA Solenoid Control signal circuit. Measured every Solenoid actuation. Two trip fault.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. ACTIVE DTC
1. Start the engine and allow it to idle.

WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE (N38) VVA SOLENOID 4 CONTROL SIGNAL CIRCUIT FOR A SHORT TO THE (N39) VVA SOLENOID 4 CONTROL RETURN CIRCUIT.
1. Turn the ignition off.
2. Gain access to the VVA Solenoid 4.
3. Disconnect the VVA Solenoid 4 harness connector.
4. Disconnect the Powertrain Control Module C2 harness connector.
5. Measure the resistance across the terminals at the VVA Solenoid 4 harness connector.

Is the resistance above 10k Ohms?

Yes

- Replace the Variable Valve Actuator Assembly. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Repair the short between the (N38) VVA Solenoid 4 Control Signal circuit and the (N39) VVA Solenoid 4 Control Return circuit.