Were you sent here from a symptom table?

Go to Step 2

Go to Diagnostic Starting Point - Front Drive Axle

1. Start the engine.
2. Inspect the instrument panel to see if the Service 4WD light is illuminated.

Does the Service 4WD light stay illuminated with the engine running?

Go to Diagnostic System Check - Transfer Case in Transfer Case - NVG 236/246-NP8

Go to Step 3

Inspect the vacuum hoses for the following:

Are the vacuum hoses kinked, plugged, or damaged?

Go to Step 4

Go to Step 5

Repair or replace the vacuum hoses as necessary.

Does the front drive axle disengage?

System OK

Go to Step 5

1. Disconnect the vacuum hose at the vacuum actuator.
2. Inspect the vacuum actuator for movement.

Does the vacuum actuator move to disengage the front drive axle?

Go to Step 6

Go to Step 7

Replace the vacuum actuator solenoid valve. Refer to Vacuum Actuator Solenoid Valve Replacement .

Does the front drive axle disengage?

System OK

Go to Step 8

Replace the vacuum actuator. Refer to Front Drive Axle Actuator Replacement .

Does the front drive axle disengage?

System OK

Go to Step 8

Inspect the clutch cable for the following:

Is the clutch cable damaged or binding?

Go to Step 9

Go to Step 10

Replace the clutch cable. Refer to Clutch Cable Replacement - Front Drive Axle .

Does the front drive axle disengage?

System OK

Go to Step 10

1. Disconnect the clutch cable from the clutch fork. Refer to Clutch Cable Replacement - Front Drive Axle .
2. Inspect the operation of the clutch fork using the J 33798 .

Does the front drive axle disengage?

System OK

Go to Step 11

Replace the clutch fork. Refer to Front Drive Axle Clutch Fork Replacement .

Does the front drive axle disengage?

System OK

Go to Step 12

The cause of concern may be in the front drive axle. Disassemble the front drive axle. Inspect for damaged components. Refer to Differential Carrier Assembly Disassemble .

Does the front drive axle disengage?

System OK

Go to Step 1