It's actually been a while since I've driven my '99 XJ much at night, but as I recall the way the headlights worked is that turning off the headlight switch before turning off the ignition caused the headlights turn off immediately. If switching headlights off after the ignition they'd stay on a minute or so to illuminate your walk to the door, escape from zombies, or whatever.

Tonight I noticed that if the headlight switch is turned off while the ignition is still on the headlights do not turn off at all until the ignition is shut off. To make things more confusing this only occurs on low beam - if high beams are on the headlights turn off with the switch as expected. Also when this happens if you flash the high beams the headlights lights will immediately turn off. (On the other hand if you turn off headlights after ignition is shut off the delay works as expected.)

I have a relay harness installed but don't think that's a factor since it's just triggered through the XJ's wiring.

Ideas what may be causing this? Or is this behavior by design and my memory is playing tricks on me?

 

I am not familiar with the behavior of the 1999 headlights, but just recently my 96 started having some headlight issues, and I have to change the headlight switch, just haven't gotten around to it. I am thinking at 20+ years, the electronics in these Jeeps are getting to the end of their life cycles.

 

Could be something going on with the headlight switch, combo switch, delay relay, or some combination of those. Of course bad grounds are always a possibility as well when faced with electrical gremlins. Fortunately at least for now it's just a minor annoyance.

 

I have accidentally left my headlight on when I've turned off the key and I just turn the key back on and they turn off. I'm OCD when it comes to leaving stuff on when shutting down for the night. I guess that comes from flying with my Dad. Everything gets turned off before the engine is shut off. That way there is no load on the battery when starting up. I've seen people with newer cars just turn the engine off, open the door and walk away, assuming the system will shut everything off and lock it automatically. I hate that! And what's with the reverse lights being on before it shuts down? Is that so you can find stuff in the trunk or hatch? Too much automatic ****!