Rear Defroster Switch
 

Quick question on a 1984 928s about the rear defroster switch: the switch pushes in but I'm not sure if it is supposed to stay in to actuate the rear defroster. The switch will push in but automatically pops out. Is this normal or do I need a new switch?SmileWavy

It should pop out to put defroster ( high power ) on and should go out in a few minutes, to defog ( low power ) turn to right ,will stay on until you turn off or shut off ignition
If the light won't go out when you turn off the key your defroster relay is shot ........@ $ 180 to 200 if you can find one new, I just went through this



From Owners manual

The rear window defogger/defroster heating
element is actuated by a push button/rotary
switch. The switch is illuminated when the
heating element is energized.
After the rear window has been cleared, switch
off the rear window defogger to avoid unnecessary
drain on the battery.
To defog - switch not depressed
0 Heating element off.
1 Heating element on. The heating element
will provide a steady energy output to keep
the rear window free from fog.
To defrost - switch depressed
0 Heating element is fully energized for defrosting.
After about 15 minutes the heating
turns off automatically.
1 Heating element is fully energized for defrosting.
After about 15 minutes, the heating
element automatically reduces energy
output to "defogging".

Thanks for the reply but I'm still not sure if my switch works. With my lights on, the switch is illuminated. I push the switch in, but it immediately releases. I am not sure if it is supposed to catch like the fog lights. Should I push it in and see if it illuminates without the lights on? I think your reply came from the manual which I have. This is the last thing I need to fix to be pretty much 100 percent. I know many people wouldn't worry about this ,but I would like to solve and move on. Thank you

with car running leave the lights off and press the button in, it's a momentary switch that triggers the" Slow Acting Relay " it should spring back and stay lit and should go out when ignition is turned off.

It is not a locking switch - just momentary - the timed on time for high mode is built into the relay. The bulb in the switch should indicate its on (brighter than with just the lights on).

Thanks to everyone who replied. This really helped me:)