SharkSkin

My RW defroster circuit seems fine up until the power leaves the panel. When I pull the connector from the bottom row, I get no continuity to ground on the two wires, T6 & T7 that go to the window. I know it's a bit of a strange circuit due to the 2-level setup, but since I get 100 ohms across each grid I should be reading 100 ohms between T6 & T7 as well as from T6 to ground, and I should be getting 200 ohms from T7 to ground. But, nada. Reads as open circuit.

Is there some other connector between the fuse panel and the rear window that might be disconnected or corroded? Where is the ground for this circuit? My rear interior light works, and the diagram indicates it uses the same ground.

Greg86andahalf

there's a multi-connector under the rear headliner near the sunroof motor. It has the defroster and the third stop light in the hatch if the car is equipped with one. look behind the rear headliner on the passenger side.

SharkSkin

I think the sunroof motor is still in Zuffenhausen... didn't make it onto my car anyway.

I'll look under the main headliner. Thanks!

Andrew Schauer

Dave,
My 1980 has a connector under the passsenger side rear trim panel, around the seat belt retractor hole. No sunroof in my car either, so maybe your plug will be in the same location.

SharkSkin

Thanks Andrew.... I'm a bit hesitant to mess with that panel, so I'll start by looking above the headliner. From your experience, is it possible to access the connector without completely removing the panel, seat, etc? For example, can I just unsnap the forward edge of the panel near the B-pillar and get to it from there? Oh, I suppose I'd have to unscrew the rosette to allow the panel to flex outward.

Andrew Schauer

I'm not sure if you'd be able to access the plug with only the top of the rear panel loose. Certainly can't hurt to try. I had mine completely out to add some sound deadening material in that area, so I didn't pay much attention to how difficult it was to access. Removing the seat, trim pieces, and panel shouldn't take more than half an hour, if you need to.

SharkSkin

Well, now I'm frustrated. Maybe I'm expecting too much of the rear defroster?

I checked and I am getting voltage at the metal connectors that attach to the grid. There's a good ground on one side and I measure the same voltage as I do at the fuse panel, on the other side. Do these things ever separate between the wire connectors and the grid?

Here's the deal... last week, on a couple of occasions, I got into the car with wet jacket & hat. The rear window fogged up, and I turned on the rear defroster. After a minute or so it didn't seem to be having any effect. Turning the HVAC to defrost(Heat plus AC, fan on high) cleared the rear window fairly quickly though. Tomorrow I'll try putting the meter directly on the grid to see if I can measure a voltage there. It only just occurred to me that the connctor might not have a good connection to the grid.

Anyway, now I'm wondering... how exactly should I expect this to behave? I have not been able to feel any heat from the grid while it is energized. Should I be able to detect the warmth, or is it subtle? How long does it have to be on before I see results... either in terms of clearing condensation/fog or detecting warmth on the grid? Please offer observations for "low" and "high" mode if possible. I know that cars vary.... I have a Saturn to compare with, and the Saturn starts clearing fog in less than a minute. Maybe the shark takes longer for the element to heat up than what my patience has allowed for so far?

SharkSkin

Monday AM bump...

WallyP

AS a general rule, you will not be able to detect any warmth at the rear window. If you check the voltage on both connections, you should have the same voltage as at the Central Electric Panel on one, and virtually none on the other - this is with everything hooked up, so that one side is grounded.

Lots of difference in inside air temp, outside air temp, how clear the air is, parked where the window is exposed to clear sky, etc., etc.

All that I can say is that mine keeps the inside clear of fog - I don't remember ever being concerned about its functioning.

SharkSkin

Thx Wally, I have confirmed voltage that far. Next I'll verify that the connectors are in fact connected to the grid. I'll probably only really need it a few times this year, but I want to be sure it's going to work when I need it. Maybe I'll try setting a pan of warm water in the cargo area if everything checks out, and see if I can verify operation that way.