I just bought a 1998 jeep Cherokee and the seller replaced the transfer case with a 231 J and then the speedometer stopped working and caused the check engine light to come on.
I did some troubleshooting and my speedometer does work after I took it out and spun the gear. I put it back and it seems to me like the gears from the output shaft and speedo gear just aren't touching.
I have a stock gear ratio with a 3inch lift and 33inch tires on. is their any way i can fix this issue?

 

The speedometer sensor unit fits into the t-case housing in 3(?) different orientations depending on the size of the speedo gear you're using. If you look closely, there should be numbers like 31-36 and 26-30 or whatnot on the end of the sensor that correspond to the number of teeth on the speedometer gear. The speedometer sensor shaft is slightly offset from the circular part that fits in the hold in the t-case, so depending on how it's inserted it'll accommodate bigger or smaller speedo gears.

 

so i should only need a bigger gear to accommodate the gap? where can I find a bigger one with 30 teeth
edit: just wondering since the speedometer isn't working at all and its not the calibration that's off also if anyone knows if i should use a short or long gear with this transfer case

 

No, the size of the gear needed corresponds to the size of the tire you're using and the ratio of the differential. See here for more info: https://www.quadratec.com/c/referenc...ar-tooth-chart

What size gear do you have in there now? It's stamped on the side of the gear. I suspect you have the sensor oriented for a larger gear, so the teeth aren't meshing for the size gear you're using. What tire size (diameter) are you running, and what's your differential ratio? Turning the sensor the right way should fix the problem. Let me see if I can snap a pic of my sensor showing the numbers once I get my kids in bed.

 

here's a pic of the orientation which should be correct my tires are 33in and i pulled out the gear but it doesn't say the teeth count the owner told me it hadn't been replaced to his knowledge so i would assume its the stock for a 1998 xj stock ratios too

 

Mine looks to be oriented the same way, and I'm running a 33-tooth speedo gear using 30" tires and a 3.55 ratio.

In case you can't read it, the numbers on the down-facing side of the sensor say 32-28.

 

Pull the sending unit out and look inside the case, make sure they output shaft has the gear on it. Does the 231 have a SYE?

 

thank you everybody for the help seems like it was just in the wrong orientation all along all I did was rotate it to the smallest setting for what i guessed was around 20-30 tooth gear on it and speedometer worked again and was pretty accurate I did order a new gear so I will have to return it anyway since the speedometer is around 3 mph faster than my actual speed which is no issue to me! thanks again.