1997 XJ, 4.0L. Today at the JY I pulled an instrument cluster (same year model), cause I had idiot lights verision w/ only gas and MPH gauges. When I plugged it up and and drove around for awhile to ensure all the gauges worked, I noticed that my odometer reading was NOT what it used to be.

The JY cluster said 145k miles. I keep a decent log on maintenance and I did my last oil change on April 18, 2012 at 156,792 miles...so I didn't bother plugging up the old one to verify. I even had a party when I crossed 150k!

I thought that all the odometer info was stored in the PCM!!!

Is it going to reset after so many cycles? I ran the old "on/off..." engine diagnostics and all I got was 12/53/55 (totally normal for my rig, I adjusted the MAP)

 

It's a bad thing that your new ICP reads lower? My full ICP added 18k to mine.. I have it all documented tho.
I believe you would have to have it flashed and the such to make it "Correct"

 

It's stored in the cluster.

 

It's strange, because I called a Jeep dealer a few years ago to ask them if the odometer would change with the cluster. They laughed and acted like it was the dumbest question ever.

 

^This.

 

As has been mentioned the reading is in the cluster. You are SUPPOSE to fill out a paper and give it to your local Motor Vehicles Department showing the milage change but I don't know of anyone who has done that.