DyeBoi

Hey Guys
Currently working on the rear defrost trying to get it working again. Last year, went in and fixed the previous problem, broken wire going to the terminals attached to the glass. After that, everything worked well.
But Winter is back and I find that my defrost no longer works again.
I figured maybe my wiring patch from the previous fix went wrong. So this morning I finally get around to tearing into the rear tail gate but I find is that the wires are still good. I check with a voltmeter between the wires and I am getting 11.5. Fuses are good, terminals to the glass look good and the grid looks to be intact and not broken. Measuring across the grid reads 0, from any one point to the other, so it seems that the power is being lost at the connections to the glass and/or somewhere on the grid?
On a side note, would all the lines have to be broken in order to get a reading of 0 across the grid? or just one or two? Any testing points that would reveal if the grid is really broken? I've tested using each side as a point, using 1 side and testing the middle of the lines, testing the same line which all have resulted in a 0 reading.

Anyone have a good digram of what wires should be attached to the glass? is there more then the 2 at the bottom right hand? (inside facing the rear). Anyone run into a similar problem and know how to fix/troubleshoot this?

I really would like to get my defrost working again as the cold and the rain only create a layer of moisture and crap that I can't look out through and is causing me nervousness at times.

Thanks in advance to anyone who can help.

Dublin

Instead of checking voltage on the grid you should be checking resistance. Think of it as a big glass toaster. If you've got voltage at the wire terminals you may not still have a good connection on the glass grid, thats what i'd check first.

DyeBoi

Ok, down here atm, testing for resistance. From side to side, only getting 3, 4 at the most. Tested from side to side, side to mid. Readings are all about 3-9, not really getting high. Anymore insight? Does passing resistance tests indicate no breaks in the grid?

Also quick clarification, all my lines seem solid, but some, the gold color is a bit missing, but the line is still completely intact. What does a break actually look like? will it be a clear cut all the way down? or does it only need to lose that gold layer?

Thanks again

Dublin

Sounds like the grid is pretty much intact, so it points to your connection point. You've got resistance throughout the grid and voltage at the connectors, so the voltage must not be making it to the grid where the spade connectors are attached. I would try cleaning the area up really well and picking up a window grid repair kit. They have them at Autozone maybe others too. You can apply the compound around the spade connection point and continue to the grid making sure not to overlap the two contact points or the two initial grid lines. Did this to mine 2 yrs ago and still working. Good Luck.

DyeBoi

Ok, I've been sitting here trying to figure out whats wrong. Some new test results.
I have disconnected 1 wire, put the glass into place so that the defroster would activate. Using the voltmeter to bridge from the disconnected wire to the grid and I get a reading, about 8, which fluctuates depending on where the point is placed on the grid. I reversed the wires, and tested again to the grid, and again I am getting about 7.9. A few spots only seemed to yield low numbers, but that still doesn't account for complete power loss.

Where is the problem? There doesn't seem to be any bridging of the spade contacts when the glass is completely up so why is there no flow? Each spade independently works, but when both wires are connected, there is no juice. Any suggestions?

Also Dublin, when you say to make new connections from the spades, where exactly did you paint? would any 2 points be alright? Or do they need to be connecting to the large bands of the grid?

Thanks again for your help and if anyone else has some perspective, don't hesitate to share.

Thanks guys

ewong

on mine - the entire doo harness was "rotted" INSIDE the insulation (the two wires that go to the defroster).

I got some neat wire (some kind of flexy neoprene coated test lead wire in a 12 gauge or something) and rebuild the harness from INSIDE the rear to the door and to the tail gate.

Me thinks the internal resistance of the harness is too high...