I thought i read somewhere that starting the car with the Auto and Recirc buttons pushed in would start a self diagnostic on my car. Doesn't seem to work when i do this, do i have the wrong info?

 

No, but you do have the wrong year. That was a method before OBD was mandated.

 

I use software but found this in the X-Type. Could be the same for our XJ's, but i gave it a quick try and nothing. The owners manual may also have some info.

Hold TRIP button and turn key to position II.
Will display Diagnostic information
If you press & hold trip reset button & keep holding whilst turning ignition key to run but not start & wait the mileage display will start flashing test! release button & enjoy, you can put your gauges through test mode then bulb test then some live information ie like engine temp, oil pressure, speed in KMH etc etc etc and any diagnostics faults may flash up as well as stored DTC codes! press & hold to return to normal.
Somewhere on the net under mustang world is a video showing dash test but not every thing is the same
You need to press and hold it before turning the ignition key to run (not start) on then turn the ignition to run (not start).

 

Yeah didn't work for me either on the XJ8