P3400

P3400-MDS RATIONALITY BANK 1

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

Theory of Operation

When all criteria has been met, power is supplied to each MDS Solenoid when the engine is making a transition from 8 cylinder mode to 4 cylinder mode. By actuating the solenoid, oil pressure is raised to the pair of lifters that coincide with each particular solenoid. The oil pressure pushes in the locking pins that allows the lifter to collapse, decoupling the valves and camshaft.

- When Monitored:
Transition from 4 to 8 cylinder mode.

- Set Condition:
O2 sensor readings on Bank 1 side indicate a lean condition while in 4 cylinder mode.





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

1. ACTIVE DTC

NOTE: Diagnose any Deactivation or Oil Pressure DTCs before continuing with this test.

1. Turn the ignition on.
2. With a scan tool, read DTCs.

Is the DTC active at this time?

Yes

- Go To 2

No

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

2. MDS SOLENOID 1

NOTE: The DTC must not be active for the actuator test to operate properly, clear all DTC before continuing.

1. Turn the ignition off.
2. Remove the Intake Manifold. Intake Manifold - Removal.
3. Turn the ignition on.
4. With the scan tool actuate the MDS Solenoid 1.

Can you feel and hear the Solenoid Actuating?

Yes

- Go To 3

No

- Remove the Solenoid and check for any debris that may be blocking the oil passages to the Solenoid. If the passages are clogged, clean the passages and replace the MDS Solenoid 1. If the passages are not clogged with debris, replace the MDS Solenoid 1. Multiple Displacement Solenoid - Removal
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. MDS SOLENOID 7

NOTE: The DTC must not be active for the actuator test to operate properly, clear all DTC before continuing.

1. With the scan tool actuate the MDS Solenoid 7.

Can you feel and hear the Solenoid Actuating?

Yes

- Go To 4

No

- Remove the Solenoid and check for any debris that may be blocking the oil passages to the Solenoid. If the passages are restricted, clean the passages and replace the MDS Solenoid 7. If the passages are not clogged with debris, replace the MDS Solenoid 7. Multiple Displacement Solenoid - Removal
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. OIL PASSAGES RESTRICTED
1. Turn the ignition off.
2. Remove both Solenoids on Bank 1 of the engine block. Multiple Displacement Solenoid - Removal
3. Remove the Bank 1 Cylinder Head. Cylinder Head - Removal.
4. Remove the Lifters from the left engine bank.
5. Inspect the oil passages to the Solenoids and from the Solenoids to the lifters.

Are the passages blocked?

Yes

- Clean the oil passages as necessary. If the entire engine is restricted disassembly of the entire engine block may be necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace both sets of lifters if no other possible causes remain.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.