Hey guys, I have been noticing lately that my rear window on my hardtop has not been working at all. I was curious if anyone ever experienced this problem and what possible things i should check to fix it. My window keeps frosting up and it really gets annoying. I have an 2002 so all the wiring and switches were already there, I just plugged the wires in to install....yes they are connected to the hardtop currently! When I press the defrost button, the light comes on the dash and I hear it click on as well. Its gonna be a little warmer tomorrow so i thought I would run some quick tests to hopefully get it working.

Thanks for any help or insights.

 

mine doesnt work either, but im not even sure if mine is hooked up

my button works, but nothing defrosts

the car was never driven in rain or snow before i bought it a month ago, so chances are, the guy never hooked it up

 

I've got an '06 that I installed a hardtop on. I don't think mine is working either. I live in Florida and have only tried it a couple of times to see if it would clear the fogged glass. It didn't do anything that I could tell. Maybe it would work with ice? I just don't bother with it anymore.

 

Mine is working, but not a great deal ....after a 10 mile drive I see some defrosting occur... to me it seems that not enough power is directed to the heating strips...

 

I wonder if it has gotten weaker with time or the unit itself is just a poor design?

 

It wouldn't hurt to double check all the harness connections. What about the switch on the driver's side striker? Maybe it became faulty and isn't redirecting the power to the hardtop. If that was the case, your softtop defroster would get the power, plus you would be able to raise the softtop (well, at least try) as that switch kills the motor, or at least the roof switch.

I installed my hardtop about a month or so ago, and the defroster starts working in just a few seconds.

 

FWIW
I have 43k miles on my S, the HT is on 3 to 6 times per year.
My defrost still works just great.

 

My '06 S2K already has 42K miles on it; the OEM hard top defroster works great... I just used it again this morning.

 

EDIT: probably a loose wire from connection between hardtop to defrost button

 

Break it down to the component parts:
1. Since you hear the relay click, probably the circuit from the defroster button to the computer to the relay is intact.

2. This leaves the relay and things distal as the likely problems spots. You can check from front to back or back to front. I would go from back to front, since the relay and wiring is unlikely to spontaneously go bad.

3. Get a voltmeter. Pop the cover at the rear window grid and check to see if there is 12 volts across the wires plugged into the defroster grid.
If you get the 12 volts, most likely the window grid is open or something is wrong with the connections, but it's in the window.

4. If there is no 12 volts, then check to see that the hardtop is seated properly in the catchers. The left side catcher has a switch which senses the hardtop and switches the power from the softtop to the hardtop. Also, this is a good reason to not continue to operate the defroster until you verify that the softop grid isn't being operated while the softtop is folded (Don't know if there is an interlock to prevent this).

I haven't tried this, since my car doesn't have a factory circuit, but if the hardtop is off and the softtop is raised, pushing the button the catcher should activate a relay near the rear of the car (should be audible) that switches the power to the hardtop wiring. This would at least tell you that the relay works. A voltmeter would tell you that power is being delivered to the hardtop wiring, if you are able to check the hardtop plug, but I would be careful to not short the connections to each other.

5. The remainder of the circuit is buried in the car, so that the only other place that you can check is to see if the defroster relay is working and maybe check the output entering the harness at the rear of the vehicle. In my car, you can reach this inside the panel behind the driver's seat, but I'm not sure where it is in an '02. Also verify that all plugs are in place and not displaced in some previous manipulation.

If all else fails, get a schematic and start tracing.