Rear Defrost not working

[Groundhog36]

The rear defogger on my 79 cherry does not work. I have not looked into the cause of the probelm yet but before I do I wish to know, is there a relay in the system or does the full current run through the dash switch. If it has a relay where is it located.

[talntar]

most of the time it is one or bpth of the wires going to the glass.they have a tendecy to come off with the window going up and down all the time

[Groundhog36]

The light on the switch does not come on either would this happern if it was at the window end?

[andy d]

just be thankful you can lower the rear window. i dont think ive ever had a wag with a working r/dfrost

[95pontiac]

I don't know if I would even use the defrost if mine did work - that is an old piece of glass to by exposing to rapid temperature changes - (frost to heat). Just my opinion...

[Matthew W. Woodruff]

There is a timer/relay inside the tailgate mounted on the regulator;

if you are very lucky, the wires may have become disconnected from the relay; plug 'em back in;

if that doesn't work and you are lucky, you can solder new wires onto the corners of the glass;

if that doesn't work and you are not so lucky the conductive epoxy on the glass has been broken in one or more places; get a kit at an autoparts store and paint it back on;

otherwise, like me, you're SOL. Get a multimeter and check for resistance across the grid, then work backwards to see where you can find power.

[Babalou]

OK. So, what if the light does not come on but when I depress the switch I hear a clicking sound? My defroster has worked on my '91 GW since new and only resently craped out on me as described above. Not that I need it here in Southern Florida...it's just one more thing to fix. I don't know what I would do if I had nothing to fix.

Thanks,

[Zorm]

ok, I'll hop on this string. The light on my rear defrost switch does come on but I get no defrost, I'll check the wiring stuff but if the realy (in the tail gate right?) is bad, would a regular auto realy work or do I need to find the one for our Jeeps??

[Babalou]

Spent too many hours today to not brake something. When I started my Rear defroster repair project today I noted that the clicking sound was no more. However, still no light on the switch or heat at the window. I quickly found the broken wire at the drivers side bottom of the tail gate window. Sottered and repaired. Checked continuity of windshield wires. Two with breaks but all others ok (plan to repair brakes later). Turned on Rear Defrost switch... clicking back again. Checked continuity from windshield to little Four pronged (3 and 1) silver box... all was good.
Now What? Could it be that little box? Only the plug from the wires connected to the glass was attached to the box (three prong plug). The other, lone prong on the box was unused. No loose wires floating around the tail gate. Tried making that prong a ground... same clicking sound (yes it was a good ground). PLEASE HELP? How do I test the little silver box?

Thank you.

[Babalou]

Does anyone know if all four prongs on the relay should be hooked up to something or just the group of three to the plug?

Thanks,

[Babalou]

Anyone? Buller?