So I just bought my first jeep, a 2000 cherokee sport. This thing has more quirks that I could have imagined. I knew it needed a heater core, and a blower motor resistor since it only worked on high. Well got the heater core in and bmr and now it won't blow at all. Then, the headlights will only turn off if I cut them off, cut off the engine then crank it back up. I replaced the headlight switch to no avail. The parking lights seem to come on when they want to and the turn signals only work with the headlights on. They worked fine before the new headlight switch. I don't know how to test the heater switch, but it doesn't seem to be melted or anything, so I'm guessing the blower motor, but I am lost on the headlights, they are his by the way, my guess is somebody didn't know what they were doing.

 

There are a few possibilities here including specific root causes, but with multiple electrical gremlins, I always start with refreshing grounds. Here's more. Otherwise, hope you are good with an electrical schematic and a meter. Good luck and keep us updated!
---------------------------------------------------------------------
Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

 

Sounds like a good place to start, I appreciate it. I'll be going in the morning to get a blower motor and going through the grounds then.

 

So I figures out if I kill the lights, then when I cut the jeep off the lights go out... the blower motor had a bad connection, which saved me 100 bucks. Now to figure out why my tuen signals work sometimes, sometimes don't even come on, and sometimes just freeze up and won't flash. Believe I'll be replacing the relay first.

 

I'll also be cleaning grounds this weekend when I replace relay. Now to work 4 days.

 

My '99 XJ has a relay that keeps the headlights on "IF" the engine is shut off first. They stay on for about a minute.
I'd say you also have a ground issue with the parking/turn signal lights. OR a burned out tail light bulb. The flasher is another possibility. MANY years ago, I had an auto where the outside lights worked fine but both dash indicators flashed. I replaced the flasher element and all was corrected. The parking/signal lights will find a ground through the other (headlights etc.) if they have no or poor ground. Use a test light (i.e. ice pick style) with the wire on the battery ground. With the parking lights on test for power at the light socket. If it's there put the test light wire on the positive and test for a light while on the ground "IF" you have a three wire socket. With all the plastic up there I'm betting there's a ground wire.

 

Sounds like a good idea. Next day off is Sunday so I'll be getting up and doing all this before I take it wheeling for the first time

 

Welcome to the club.

 

Post some pics from out wheeling.