I found this:
http://roman.fizteh.ru/cherokee/exj_8w-arpfyddzl7u.pdf
It links to a full electrical diagram for an XJ Cherokee, not exactly certain if the year matches, but they have diesel bits in their document.
Also there are these:
http://www.thailandoffroad.com/jeep/...00/exj_14a.pdf
There is some stuff in there about PCM faults, but no wiring I can see
http://www.jeep.on-line.no/documenta...0XJ/01XJED.PDF
Trouble shooting guideline for a 2001 XJ but same diesel engine from what I can see.
Sorry, I hope this helps