Fuse for rear defroster 00 sport

Rear defroster hasn't worked since the day I bought it in 02. Since it doesn't work and the light on the switch doesn't illuminate, I'll start with fuses. Anyone know where the fuse is, and if there is any other fuse inline somewhere? Thanks in advance. (No need to reference my similar post from 3years ago which yielded no results).

Fuse 12 or Fuse 14 located in the Junction Block. The junction block is located behind a removable panel in the right front (passenger) kick panel.

Fuse 12 is the fuse for the rear window defogger relay and fuse 14 is for the rear defogger indicator.

If fuse 12 is good and there is no voltage at either side of fuse 14, it's probably the relay that I believe is also located in the Junction Block. When energized by current flowing across the coil from fuse 12, the circuit points close and seperates into two circuits, one to the defogger grid on the back glass and one through fuse 14 to the switch illumination diode.

Good luck,
Tom

wow, thanks for the great answer. After further review, fuses 12 and 14 both pass visual inspection, as do all others in that box. # 9 and 13 are absent, I'll assume options I don't have?) so I tried a 10 in both anyway, still no worky. I assume there is no power to 12 or 14 but haven't checked. Any other suspects, or just start chasing the wire back from the box?

Thanks in advance for your help. This'll be our eighth winter in the jeep, and the defroster repair would sure be amazing.

the_chief said:

wow, thanks for the great answer. After further review, fuses 12 and 14 both pass visual inspection, as do all others in that box. # 9 and 13 are absent, I'll assume options I don't have?) so I tried a 10 in both anyway, still no worky. I assume there is no power to 12 or 14 but haven't checked. Any other suspects, or just start chasing the wire back from the box?

Thanks in advance for your help. This'll be our eighth winter in the jeep, and the defroster repair would sure be amazing.

Click to expand...

I really do not like offering electrical advice, I try an make it simple but get concerned the listener may think I'm talking down to them. I'm not, just trying to be clear.


Got a test light?

Fuse 12 is switched power. The ign key needs to be in the run position.
Current runs from fuse 12 to the coil of the defogger relay. The ground side of the coil is switched through the defogger switch. <If the switch is bad, or the ground is bad the relay coil won't energize> If everything is working throwing the switch energizes the coil.

with the coil energized the solenoid contacts close.

BAT voltage <always on/hot> It enters the relay and crosses the contacts. This circuit divides. The 1st current path flows through Fuse 14. <so if Fuse 14 has voltage the relay works> The BAT voltage into the relay comes from the Power Distribution Center under the hood, Fuse 11. <Check this>

If fuse 14 is good, the little yellow lamp in the switch should be illuminated when thrown, If not either bad switch or bad ground.

Fuse 14 also feeds the heated O/S mirrors. Are they working?

Could use the test light or ohmeter to check for current at the rear defogger itself. Lots of times the heating element on the window is damaged. Loctite makes a little repair kit if you can figure out where the grid is broken.

OK, looking at wiring diagram shows that if only thing wrong is the heating element, the indicator light on the switch should still light up.

Yes stretch a test light with the probe on the left side of the glass and the clip on the passenger side would light when current is being sent across the grid. A test light is used to determine where on the grid is the open circuit.

Find the ground side of the grid and place the clip there. Using the probe test each grid line by sliding the probe along from positive side towards ground.`as long as the lamp in the test light is illuminated then the continuity is good, should the ligth extinguish you found the break.

The other way is to energize the switch, you said the yellow indicator was lit, place your finger on the o/s mirror, they are heated and after about 5 minutes warm to the touch. I did this on the way to work this morning to determine if I could feel the difference, and yes I could.