LedJeep

I'm looking for some help as to why the #25 fuse in the PDC keeps blowing when I turn on the fog lamps. My fog lamps have never worked since buying my XJ in '09 so I started chasing it down today and every time I hit the switch the fuse blows. I have new lamps and a new switch installed.

Thanks!

BlueRidgeMark

The fuse blows because you have a short. The question is, "Where?"

I'd check the relay first. Swap with another one that is known to be working correctly.

If that doesn't solve the problem it's time to dig into your circuit to find out where the problem is. The time and frustration saving technique for this is called, "circuit splitting" or "half splitting".

http://www.technology.heartland.edu/...t%20Method.doc

http://firetrucksandequipment.tpub.c...-9-254_231.htm

LedJeep

It shows two relays in the PDC, should i replace them both?

BlueRidgeMark

Test first. Just swap with a known good relay as a test.

nujeepguy

pull the fuse. measure resistance of fog wires to ground. if shorted pull the bulbs to be sure. it sounds like a simple shorted fog wire. stop wasting fuses!!

LedJeep

I swapped out the relays and blew another fuse....nujeepguy says to measure resistance of fog wires to ground. Please excuse my lack of knowledge, how do i do that?

nujeepguy

could unhook batt when doing ohm reading,the ohm meter dont like volts!
then go to low ohms, hook one lead to good ground, the other to the fog wire. with lights it will read low but not zero.
pull bulbs to check just the wire with nothing connected. should read open.
you could have a bad switch flip it on/off,again fuse / relay out so no volts can show up!

oh, always check meter by touching leads both together,and to ground to verify good ground contact. this is one area that a loose/bad ground can be trouble