GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 Driveline/Axle 🢒 Front Drive Axle 🢒 Four-Wheel Drive Does Not Engage

Four-Wheel Drive Does Not Engage A4WD

Step

Action

Yes

No

1

Were you sent here from a symptom table?

Go to Step 2

Go to Diagnostic Starting Point - Front Drive Axle

2
  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

3

Inspect the vacuum hoses for the following:

    • Kinks
    • Plugged
    • Damage
    • Disconnected

Are the vacuum hoses kinked, plugged, damaged, or disconnected?

Go to Step 4

Go to Step 5

4

Repair or replace the vacuum hoses as necessary.

Does the front drive axle engage?

System OK

Go to Step 5

5
  1. Press the 4HI button to attempt to engage the front drive axle.
  2. Disconnect the vacuum hose from the vacuum actuator.
  3. Inspect for vacuum at the vacuum actuator.

Is there vacuum at the vacuum actuator connection?

Go to Step 6

Go to Step 7

6

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

Does the front drive axle engage?

System OK

Go to Step 8

7

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

Does the front drive axle engage?

System OK

Go to Step 8

8

Inspect the clutch cable for the following:

    • Damage
    • Binding
    • Disconnected

Is the clutch cable damaged, binding or disconnected?

Go to Step 9

Go to Step 10

9

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

Does the front drive axle engage?

System OK

Go to Step 10

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 engage?

System OK

Go to Step 11

11

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

Does the front drive axle engage?

System OK

Go to Step 12

12

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

Does the front drive axle engage?

System OK

Go to Step 1