This one has me perplexed, I have a 2004 Rubicon with a non functioning rear locker. Not sure when it broke but it was most likely when I was on the Rubicon trail a few months ago. Here is what I've done so far to troubleshoot:
- LSD seems to be functioning correctly as the Jeep still chirps around corners at slow speeds in the parking lot
- When the rear locker is activated the air pump cycles and stops, the "REAR LOCKER" light in the dash stays solid
- I pulled the rear diff cover off yesterday and found no metal debris in the oil
- The axle has been put in the air and wheel rotated to confirm the axle is not in fact locked when the Jeep says it is
- No audible sounds coming from the diff that would be indicative that something isn't right
- When activating the rear locker you can see the locker collar slide over from the air pressure. So it appears that air pressure to the locker and bladder is good and it's actuating. A 5 second video of it can be seen here: