Will not stay in 4lo

I have a 2 quick questions...
Went wheelin this weekend, my first real/legal trip. Place called haspin acres. 700 acres of open trails. Went with 8 other jeeps.
Ok... had my XJ a while now... been in 4lo plenty of times. But for some reason, Saturday, the jeep would not stay in 4lo unless i pulled the lever back and held it as i went thru the obstacle.
I do have a home made tc drop and someone mentioned that it may be the cause. What do you think.
Also on the trip... I was sitting on a small incline, waiting for a Renagade to get out of a deep rut... glad the XJ has a wider stance... anyway.. sitting... bout 5 minutes and the check engine light came on... XJ running fine.... made it up the rut and to the top.. shut the XJ to watch the other guys... Got back in and the light never came back on.
Do you think this is something I should look into?


thanks a lot...

Doug

When mine did that it turned out to be just the adjustment of the shift linkage. I'd try that first before worrying too much.

If it's a plain old NP 231, the procedure is simple. Shift to 4-low, then get under and loosen the adjusting bolt on the linkage rod that leads to the lever on the transfer case. Make sure it's nice and free, then give the lever on the TC a nudge to ensure that it's really all the way into 4 low. Then retighten the bolt. When you go back to 2 high, the handle should be pretty much parallel to the floor. If it's tilted up, it will tend to pop out of 4 low.

This is a side effect of T-case drops, I had to do the adjustment also. If you have an FSM it shows in detail how to do the adjustment. IIRC this may even be outlined in a Haynes manual.

You have to remove the in cab bezel around the 4WD shift lever, you will see the lever rod go down through a metal plate with gates for the 4L N 4H positions. You need to shift the case all the way to 4L and insert a 1/8" spacer between the rod portion of the handle and the metal gate, this allows extra room to push the linkage that little bit to ensure a positive shift. An assistant can hold this in position against the spacer for you while you perform the next part.

Then get under the truck and loosen the trunnion bolt on the linkage and push the lever on the T-case fully into the 4L position. When you have all this in place the adjuster rod should have moved to a new position, now you can re-tighten the trunnion bolt back up, remove the 1/8" spacer and replace that interior bezel and you're all set.

All my problems went away after the adjustment, even the slight binding I was getting during shifting.

HTH,

Mark

Thanks for your help!