Hi Darren
There is a control unit. It is located under the passenger seat next to the ASCD. That is... if you have auto defogger.
For either defogger setup, though, you should have power on only one of the wires to the grid. These wires are the furthest outboard if you have 4 wires. The two inboard control the auto defogger.
When the defogger is activated either manually or automatically, current flows from one of the outboard wires, through the grid, and then through the other outboard wire to the ground.
So I would disconnect both wires, and test each for power, if I have power on one I would test the continuity to ground on the other. If that's all good the only thing left to be bad is the grid.
Bob A.
> Is there a control unit for the rear window
> defogger in the '82 280ZX? I have replaced
> my
> switch and I am still only getting voltage
> to
> one side of the grid contacts. I thought
> that
> one of the grid lines might be broken but,
> they are all intact.
