P3400

P3400-MDS RATIONALITY BANK 1

For a complete wiring diagram refer to: Electrical Diagrams

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 8 to 4 cylinder mode.

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

Possible Causes
- INSUFFICIENT OIL PRESSURE ACTING ON THE LIFTER LOCKING PINS
- OIL PASSAGES RESTRICTED
- LIFTER
- MDS SOLENOID

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding

Diagnostic Test
1. ACTIVE DTC





Ignition on, engine not running.
With a scan tool, read DTCs.

NOTE: Diagnose any Oil Pressure DTCs before continuing.

Is the DTC active at this time?
Yes >> Go To 2

No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. MDS SOLENOID 1





Turn the ignition off.
Remove the Intake Manifold per Service Information.
Turn the ignition on.
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 pas sages are clogged, clean the passages and replace the MDS Solenoid 1. If the passages are not clogged with debris, replace the MDS Solenoid 1.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. MDS SOLENOID 7





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 pas sages are restricted, clean the passages and replace the MDS Solenoid 7. If the passages are not clogged with debris, replace the MDS Solenoid 7.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. OIL PASSAGES RESTRICTED
Turn the ignition off.
Remove both Solenoids on Bank 1 of the engine block.
Remove the Bank 1 Cylinder Head per Service Information.
Remove the Lifters from the left engine bank.
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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace both sets of lifters if no other possible causes remain.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test