Diagnostic Test

Ignition on, engine not running.

With a scan tool, select View DTCs.

Is the DTC Active at this time? 

Yes 

1. Go To  2.

No 

1. Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

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 

1. Go To  3.

No 

1. 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.
2. Perform POWERTRAIN VERIFICATION TEST .

With the scan tool actuate the MDS Solenoid 7.

Can you feel and hear the Solenoid Actuating? 

Yes 

1. Go To  4.

No 

1. 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.
2. Perform POWERTRAIN VERIFICATION TEST .

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 

1. Clean the oil passages as necessary. If the entire engine is restricted disassembly of the entire engine block may be necessary.
2. Perform POWERTRAIN VERIFICATION TEST .

No 

1. Replace both sets of lifters if no other possible causes remain.
2. Perform POWERTRAIN VERIFICATION TEST .