AWD but no 4WD

[AutoPlus]

Good Day, I've got a rather odd problem I do see in any of the the threads. My 03 Expy 5.4 will not go into 4wd. I seem to have Automatic 4wd but no 4 Hi or 4 lo. The odd thing about the transfer case is that it will engage 4 lo but no engagement of the front axle. Any suggestions are appreciated, thanks in advance.

 

[Bedrck47]

Some things to check Start with checking fuses with a meter

Symptom Chart

Symptom Chart Condition Possible Sources Action
The vehicle does not operate correctly in A4WD and 4WD HIGH modes
Central junction box (CJB) fuses:
11 (10A).
115 (30A).
20 (30A).
Mode select switch (MSS).
Transfer case shaft speed sensors.
Transfer case electric clutch.
4WD control module.
Powertrain control module (PCM).
IVD.
IWE solenoid.
Circuitry.
Go To Pinpoint Test B .

No communication with the 4WD control module
Central junction box (CJB) fuses:
115 (30A).
20 (30A).
4WD control module.
4WD control module connectors.
Circuitry.
Go To Pinpoint Test C .

The vehicle does not shift between 4X4AUTO/4WD HIGH and 4WD LOW modes correctly
Central junction box (CJB) fuses:
11 (10A).
115 (30A).
20 (30A).
Mode select switch (MSS).
Gearmotor encoder contact plate A, B, C, or D.
Gearmotor encoder assembly.
Circuitry.
4WD control module.
Transfer case internal mechanism.
Transfer case shift motor.
Digital TR sensor.
BPP switch.
IVD.
IWE solenoid.
4WABS control module.
Instrument cluster.
PCM.

 

[AutoPlus]

Lots of good info, Thanks!

 

[Goats]

I have the same issue ,I just haven't gotten around to it

 

[bnicov]

Tap the motor on the transfer case with a hammer. Don't smash at it but give it 3-4 taps and then try to see if it works. If it does, you will probably be needing a transfer case motor soon. At least once a week, switch to 4hi then 4lo and drive a few feet in forward and reverse to exercise the system and kepp it moving.