Hi Guys! Brand new here... I've got a '90 2dr XJ that I'm working on and I came across this situation. I've searched for the last 2hrs on both google and on this board with no success, so now I'm reaching out for help...

I went to the boneyard a couple weeks ago to grab a wiper transmission among other smaller things and I found a 2001 XJ 4dr that had A LOT of useable interior pieces... I scored a new style dome light with the clear lens and separate map lights... There lies my issue...

I pulled my old dome light off and found the harness plug to be identical EXCEPT that the new light has 3 prongs where the old light has 2. The existing wiring harness DOES have 3 holes to match but only 2 holes have wires attached. I plugged it in with the doors open and got nothing. I clicked on one of the maplights and it came on but only about 1/2 brightness, clicked on both and they each came on but at only about 1/4 brightness but the domelight popped on about 3/4 brightness... So the domelight will only work if both maplights are on, but is not as bright as it should be, and the maplights are never as bright as they should be... This is just weird to me...

Anyone ever used the new style domelight in an older XJ with success, and if so, what did you have to do to make it work correctly?? Not sure if it matters, but the new domelight has the keyless entry receiver mounted in it, but it connects with a separate harness so I'm thinking it doesn't...

Any help will be greatly appreciated, THANKS IN ADVANCE!!!

 

check both wires to the light with a test light to see if ether is a ground

if one is a ground then the 3rd connector will need new hot wire run to it

if both wire are positive then ground the 3rd connection

this is a guess

 

That's what I thought it might end up being, but I wanted alil backup before I went to that trouble and had that not be it... If it ends up being that I do need a 2nd hot wire, do you think it'd work out ok to t-tap off the existing hot wire to create the 2nd hot lead? I'm planning on running LEDs in there which is why I wanted the new style light in the first place. Much less wattage with the LEDs so 1 wire split to feed both 12v inputs should be fine, yes?

Thanks again!!!

 

you may want a constant power source for the reading lights
the existing one works of the door switch

 

one is a ground, one is constant 12v for the map lights other is the interior light for the door