Once in a while, accelerating normally my xjr wont shift out of first gear from
a dead stop. Say from a red light. I have to pull over and turn the car off
and on again. it will shift after its been restarted. I've only got 30k miles on the car.
What could it be? I'm figuring something electronic is wrong.?

 

The trans is electronically controlled but there are also mechanical problems that could cuase it not to shift. The fact that shutting it off restores normal operation I'd suggest an electronic issue. This "failure mode" doesn't fit the usual ZF death throes either.

 

A local transmission shop said he would look at a switch that is located near the brake and another one that is on the transmission...? This guy is a family friend
so he wants me to bring it to him to read any codes it may have.

 

Looking for codes is certainly important. I don't see what year your xjr is, so no one knows what transmission you have.

 

It's a 1998.


Thanks!!

 

All XJR's are fitted with the Mercedes based box and not the ZF's as fitted to
NA models.
With such a low mileage for it's age, I would be taking it to a transmission specialist to have the fluid and filter changed and checked out for any other issues.
You have to remember, it's a 15 year old car but 30k over this period is not normal.

 

How old is the battery? if it's original it'll probably need changing, cold out where you are right now?

do a 'hard reset' first then 'retrain' your gearbox - both easily found if you search the forum.

The delay in gearshift is a classic symptom of the fluid level within it being either too high or too low and cold. Might need checking, which needs a special benz dip stick tool, another item you can get the spec off this forum with a search. Use Benz trans fluid for the 722.6 in your car.
Hope this helps.