Jeep Repair: 02 TJ Headlight wont shut, using a multimeter, fog lights

Question
Hello,

Even after shutting down the motor, my front headlight will not shut down. The fog lights will not work.

After taking off the underhood fuse(Hd/Lf) 40A.The headlight will shut down and fog is working properly.

How can I fix this problem?

Thanks very much in advance for your help.

Answer
The grounds for these lights are basically hard-wired to the chassis so we can rule out everything from the headlights to ground.  That leaves just the power side of things and on your's the circuits lead back to two power sources.  Low beam power comes from that fuse, to a circuit breaker, to the multi-function switch and then on to your headlights.  In addition the daytime running lamp module (if equipped) can feed power to the lights too.  By removing the fuse 10, 40amp, like you did my thoughts are that would mean that the power is coming souly from this fuse.

The only other thing you could do is check the multi-function switch (headlamp, high beam, wiper stalk) by unplugging it and seeing if the lights turn ou.  My guess is that they do.  There's a way to check the switch using a multimeter and changing light positions.  If you have a meter let me know and take out the multi-function switch and I'll talk you through the diagnostics.

Otherwise, you'll PROBABLY just be ok to go ahead and replace the switch.  I know on the WJ's of your time period they would actually kill batteries because the customer would walk away and the lights would turn off and on intermittantly over-night.
Doug