Bench testing rear defroster

[ErickSaint]

This weekend I will be pulling my rear window to repair most of the lines on my defroster. Since having the truck I only have 2 lines that work. Everything I have read says to do the repairs with the glass at room temp, so I was going to just pull it off and bring it in the house. I know there are many breaks in the lines so I would like be able to test indoors once the repair paint dries.

What is the best way of doing this? When using a test light (self powered or otherwise) my guess is it would still show continuity because there are 2 lines that work, therefore making a connection. Same would most likely apply with my DMM set for continuity.

I do have a 12v power supply from when I used to work on CB and stereo hardware. The problem is it's 13.8v with 10 amp constant and 12 amp surge, so my guess is that the defroster would put my PS in protection mode pretty quick, I know it draws more than 12 amps.

Radio Shack used to sell a "Circuit Writer" pen that I have been told works just like the kit, for half the price, but no local RS stores have them any more. If I could find that I would just mask off every line and apply a whole new line instead if trying to find every little break (there are many from what I can see) looks like the previous owner used to close the glass on things all the time. The kit from checker auto is $12 and comes with a tiny bottle of the paint.

Any tips so I don't have to try installing, removing and reinstalling if all breaks are not found. Wouldn't be so much of a problem in summer, but it's supposed to be a high of 7 degrees on the weekend so doing it outside just seems out of the question.

 

[ErickSaint]

Ok, so I have been all over the net looking for this info, and getting nowhere. I know how to test the glass in truck with the leads attached, but no info on doing it out of the truck. Has anybody tried to test the defroster while at a bone yard with no power? If so how did you test it?

I have also read that the window should read a certain resistance if all lines are in tact. Does anybody know where to find this info for the window in a 94? If I knew the resistance I could check the ohm reading with my DMM.

 

[Blacksheep Josh]

maybe a haynes?

 

[wood1]

You can use a test light. Turn on the defroster and attach a test light lead to a ground and start checking the grid. As you go from the hot side to the ground side the voltage will drop unless you are on a line that has a break. If it has a break the light will simply go off when you reach the break.

Buy a defroster repair kit and bridge the breaks with it. Make sure you prepare the surface well, rub it with some fine steel wool and wipe it down with alcohol. They usually come with a template but tape will work too.

Good luck.

EDIT:
Sorry read your post again, basicly the same applies but use a multimeter and go by resistance value.
Start on the ends of the lines and you will be able to tell if there is a break and where it is. Fix it then compare the repaired areas to the two that didn't need fixing. Let the stuff cure for the proper time and plug it back in, won't be that much trouble. especially if you have a helper to hold it in place while you test it...

 

[killswitchfan134]

how do you remove the power wires to the rear defroster to remove the window?

 

[ErickSaint]

pretty sure on mine the wires are just attached to the tabs with spade lugs, just gently pull them off the tabs.