NP231 vs NP242: how to identify your transfer case and what modes mean

Overview

Most XJs have the NP231, which is part-time only, you should not run it in 4WD on dry pavement. Some XJs have the NP242, which has a full-time AWD mode that is safe on any surface. Knowing which one you have matters for how you drive the vehicle and what internal parts are compatible if you ever need to rebuild or upgrade it.

What you need

• Basic hand tools
• Flashlight
• Optional: multimeter

Quick checks first

1. Quick check 1
2. Quick check 2
3. Quick check 3

Step-by-step

1. Step 1
2. Step 2
3. Step 3

If that did not fix it

• Next likely cause 1
• Next likely cause 2

Source links

• JeepForum: NP231 or NP242 (identification discussion)
• NAXJA: NP231 vs 242 differences

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