Just got a new hatch glass (thaks jimeby). Does anyone know how to test the rear defroster? I want to verify it's good before I have it tinted and install it.

 

I think if you have a test meter, you should be able to run a current through it to see if the circuit is intact.

 

That's what I think too, but I'd like to know what resistance to look for. Don't want to spend all that money tinting the glass to find the defroster is bad or even questionable.

 

As long as any current makes it through, you'll know that the wiring is intact and functional. Just feed 12 volts through one side, then check for current at the other connection. No current = broken circuit.

 

If I'm going to do that I have another question. There are 3 electrical connections on the glass, does it matter which ones I connect the battery too? I don't think polarity will be an issue, will it?

 

Why connect a battery at all? Just ohm the sucker with a DMM.

 

That was my original idea, but the dealer service dept brought up a good point...if you check resistance it can still have one bad filament and I'll get a resistance reading. Same thing if I just hook up a battery and read the current. It could have a bad branch and you'd still get current flow. The dealer says to hook up a battery and use a test light to check each filament of the defroster, but that will only tell me that voltage is getting to the filament. Other than that they can not tell me what I should see. First inclination is to say the test light will light when you touch each filament, but it will do that even if there is an open in the filament (according to Kirschoffs law, you will read source voltage across each branch of a parallel circuit). So I guess the only true way to find out if it works is to try it and see.

 

Before I tinted mine, I tested at the main connectors, with an ohm meter. I then tested every line seperately. Out of 3 hatches, I found one with readings on all the lines, that's the one that was tinted.

Iirc the FSM or Haynes shows how to test and make repairs.

 

So how did you test each line seperately? What resistance did you see?

 

Just wait for some snow or ice and then test the sumbitch. It won't be long.

Or just get in the garage and measure the temperature along each branch, turn it on and retest. You will see a difference in temp across-the-board if it's working correctly.

 

Like I said, I want to do it before I go to the trouble/expense of tinting/installing it. Plus my RX is sitting in my garage stripped to the bone in the process of a ground up rebuild.

 

Use an ohm meter to test the continuity of each wire. It's quite simple.