I have checked around and am still not quite sure how to proceed. Maybe I missed something in another thread but...

1983 242. Rear window defroster doing nothing - no effect, no lines in the grid showing even partial joy. I see no relay in the wiring diagram for this year and the switch is not a momentary switch - just a simple on/off with a light that does light up when turned on.

In the back seat with my meter set to sound on continuity, power off, defroster switch off. I put the probes on both side tabs simultaneously and get a sound. Is this continuity from the grid? Or something else?

In the back seat with my meter set for volts DC, power on (but engine not started), defroster switch on. Dome light was on when I switched on the defroster and there was no dimming of the bulb as I have read might happen. With probes on both side tabs simultaneously, I get 11+ volts. So the switch seems to be working, power is being delivered, and it seems that there is good ground somewhere.

Should I conclude there is something wrong with the grid wires at this point?

A visual inspection from inside reveals nothing obvious - like breaks in the grid wires. If I understand properly, ones that are broken will not heat but should not affect unbroken ones. Yet none seem to provide any defrost.

A visual inspection from outside shows what might be oxidation - like small spots of discoloration on the wider strips to which the tabs connect. Nothing looks completely rotten or broken. I guess this might be expected for a car this old. I don't see this on the thin grid wires but it is much more difficult to see as they are much thinner. Are these conductors embedded inside the glass? I was under the impression they might be applied to the glass.

Can anyone suggest further tests/actions I can perform to try and isolate the problem and get defroster working again? I am pretty lame with electronics. But can follow instructions.

Thanks in advance.