Hey

On a friend's TP, I repaired the Rear Demister/Defogger Tab with a Permatex repair kit for both the tab adhesive and gridlines. After steaming up the rear window almost totally though, the demister didn't work.

Any ideas why? The fuse was fine (20 amp).

Originally I took the job on because while the cable was being reconnected to one of the tabs recently, the tab broke off the grid.

Curioso

Just ran a multimeter over the tab and grid area. No current gets through to the grid but there is 12 volts at the tab. That's because there is light shining through the connection. I'll have to put some more adhesive/conductive paste over those broken areas so current can get through.

The tab on the other side of the car is at chassis voltage.

I put some adhesive/conductive fluid around the unsealed areas (the tab's perimiters - it has two as there are two connecting surfaces to the one tab). It didn't work, even after leaving it for several days. The solution is to remove the tab again and reposition it over live grid. Putting it back where it came from does not form a bridge between it and the overall window grid.

I'll do that tomorrow and get back to you on the outcome, for those of you who have a similar problem.

Curioso

To finally close out this thread, I eventually took the car to an auto electrician who repositioned the demister tab on an undisturbed area of grid way off to the edge of the window. That didn't work on its own though, so he then got some conductive paint and painted three coats over the whole area, to connect the tab to live gridlines.

In the end, it actually worked when I tested it by steaming up the rear window and running the demister (it does have a 5-10 minute lag time to get underway though). So that is the solution if you're having trouble with this.