Searched to no avail, but didnt all XJ/s (84-92?) come with all interior power harnesses, even if the option isnt available on the XJ's (such as power locks, windows, rear wiper system)? I want to put a rear wiper system on my 89, but didnt come with one stock. I remember seeing an unused wiring harness under the drivers side carpet and someone said that the XJ's usually came with a full harness. So, would the existing harness already be in my XJ but a matter of installing the wiper motor/arm/switch?

 

Yes, and for the rear wiper everything to the relay should be there last time I had my hatch apart. However, I have not pulled the quarter panel to see if the pump wiring for the washer bottle is there...