84 325e (real early 6-hole 3 series, 2/84 build) car is theft recovery. lots of damage in and around steering column/dash. above the (hole for) the radio are three buttons, l-r: hazard, rear window defogger, window/sunroof button circuit reset. SHOULD the rear window defogger light up with it (a) pushed "on" or (b) with the headlights on. the defogger does not work, but I suspect the switch is the issue...I replaced original with one from the junkyard to no effect. perhaps another one. but is there a light to indicate that the switch itself seems to be working?
It should light up when pushed/on, even with the lights off. I have never taken the switch apart to see what type of bulb is required. Ours is a 4/85 325e.
You just pop the cover off, which is not the easiest thing in the world. A pick works nicely. Then, just pop the old bulb out and put the new in. Works the same for hazard and AC switches, too. Bulbs are 1.2 watt wedge based bulbs and cost about $1.50 each at Auto Zone.