HELP!!!!!
91 Jeep XJ, Dana 30 front and rear, automatic, try to shift to 4high and won’t engage, part time light does not come on either, shift to 4low and 4low engages and part time light still doesn’t come on. What could it be? Are there multiple vacuum lines? First time Jeep owner and first build, learning as I go.

 

Are you shifting while driving or sitting still?

 

In addition to Cruiser54's question, the lights for transfer case position can take a while to come on or change.

 

Here:


Shifting the NP/NV242J Selec-Trac Transfer Case

2WD Position
This position is for driving on hard-surfaced roads under normal driving conditions when 4-wheel drive is not desired.

4x4 PART TIME Position
This position is designed for temporary use of 4-wheel drive when on-or off-road conditions such as deep snow or heavy ice require increased traction. When engaged, both the front and the rear axles are mechanically locked together and turn at the same speed. Do not use 4x4 PART TIME on dry, paved roads.

To engage, shift transfer case from 2WD to 4x4 PART TIME while the vehicle is moving at any legal speed.

An amber PART TIME lamp will illuminate on the instrument cluster when 4x4 PART TIME is selected.

4x4 FULL TIME Position
This is the primary 4-wheel drive position, which offers better traction when roads are wet, snow covered or icy. When engaged, the front and rear wheels axles are permitted to turn at different speeds to enhance maneuverability. Use 4x4 FULL TIME year-round on all road surfaces if you wish.

To engage, shift transfer case from 2WD to 4x4 FULL TIME while the vehicle is moving at any legal speed. When shifting, do it in a swift and firm movement.

When shifting from 2WD through 4x4 PART TIME to 4x4 FULL TIME, two momentary releases of the accelerator may be required after shifting.

A green FULL TIME lamp will illuminate on the instrument cluster when 4x4 FULL TIME is selected.

4 LO Position
This position is designed for temporary use of 4-wheel drive when off-road conditions require added low speed pulling power. Do not use 4 LO on dry, paved roads.

To engage, slow the vehicle to 2-3 mph (3-5 km/h), shift the transmission into Neutral (N), then shift the transfer case lever to Neutral, then to the right and pull firmly rearward to 4 LO.

Never attempt to engage Low Range when the vehicle is moving faster than 2-3 mph (3-5 km/h). Transfer case damage may result.

An amber PART TIME lamp will illuminate on the instrument cluster when 4 LO is selected.

 

im sitting still when I shift into 4wd

 

Thats why you're having issues.

See Post #4

 

I’ll wait for a couple mins sometimes and the light will not come on

 

Tap and let off the gas.