Page 361 of 5267

5.(K451) MDS SOLENOID NO.1 CONTROL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Measure the resistance between ground and the (K451) MDS Solenoid
No.1 Control circuit in the MDS Solenoid No.1 harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (K451) MDS Solenoid
No.1 Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
6.(K451) MDS SOLENOID NO.1 CONTROL CIRCUIT OPEN
CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller Special Tool #8815
to perform diagnosis.
Measure the resistance of the (K451) MDS Solenoid No.1 Control cir-
cuit from the MDS Solenoid No.1 harness connector to the appropriate
terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 7
No>>
Repair the open in the (K451) MDS Solenoid No.1 Control
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
Page 362 of 5267
7.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 363 of 5267
P3402–CYLINDER 1 DEACTIVATION CONTROL PERFORMANCE
Page 364 of 5267

For a complete wiring diagramRefer to Section 8W.
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:
The MDS fails to disengage for cylinder 1. One trip fault.
Possible Causes
(K451) MDS SOLENOID NO.1 CONTROL SHORT TO VOLTAGE
OIL PASSAGES RESTRICTED
LIFTER
MDS SOLENOID NO.1
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.MDS SOLENOID NO.1 CONTROL CIRCUIT
Turn the ignition off.
Disconnect the MDS Solenoid No.1 harness connector.
Ignition on, engine not running.
Turn off all accessories.
Using a 12-volt test light connected to ground, probe the (K451) MDS
Solenoid No.1 Control circuit.
Does the 12-volt test light illuminate?
Ye s>>
Go To 3
No>>
Go To 4
Page 365 of 5267

3.(K451) MDS SOLENOID NO.1 CONTROL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Turn the ignition on.
Measure the volage on (K451) MDS Solenoid No.1 Control circuit in the
MDS Solenoid No.1 harness connector.
Is voltage present?
Ye s>>
Repair the short to voltage in the (K451) MDS Solenoid
No.1 Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No>>
NOTE: Before continuing, check the PCM harness connector ter-
minals for corrosion, damage, or terminal push out. Repair as nec-
essary.
Replace and program the Powertrain Control Module per
Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
4.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?
Ye s>>
Go To 5
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.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
Page 366 of 5267
5.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?
Ye s>>
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. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace both sets of lifters if no other possible causes remain.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 367 of 5267
P3425-MDS SOLENOID 4 CIRCUIT
Page 368 of 5267

For a complete wiring diagramRefer to Section 8W.
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:
When the PCM recognizes a problem with the Solenoid Control circuit. One trip fault.
Possible Causes
(K452) MDS SOLENOID NO.4 CONTROL SHORT TO BATTERY VOLTAGE
(K452) MDS SOLENOID NO.4 CONTROL SHORT TO GROUND
(K452) MDS SOLENOID NO.4 CONTROL OPEN
(Z903) GROUND CIRCUIT OPEN
MDS SOLENOID NO.4
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.MDS SOLENOID NO.4
Turn the ignition off.
Gain access to the MDS Solenoid No. 4.
Disconnect the MDS Solenoid No.4 harness connector.
Ignition on, engine not running.
Turn off all accessories.
Using a 12-volt test light connected to the (Z903) Ground circuit, probe
the (K452) MDS Solenoid No.4 Control circuit.
With a scan tool, actuate the MDS Solenoid 4.
Does the 12-volt test light flash on and off?
Ye s>>
Replace the MDS Solenoid No.4.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3