Without seeing a picture, I would venture to say you have one with a light. You should see a switch on the bottom of the mirror. Not a real common option from GM, but cool if you have it!
Yes, on the bottom of the mirror you'll see a small rectangular clear lens. Slide that lens. Sliding it turns the light on or off. That is the map light mirror, an optional item.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
I'll see if I can post an exploded view photo a bit later. You appear to be missing the terminal at the end of the wire, so this might be a bit of a challenge. Also, your wire doesn't look to be in the best shape, so that may pose even more of a challenge.
You have to sort of squish the lens-switch slider under the mirror and gently pull it out to access the bulb. In your case it might be worth separating the mirror housing from the lens and rubber gasket to run a new wire to the switch. It's easy to glue back together after. This also reduces the risk of breaking the slider which can be very fragile after 50 years.
BTW, you must have option ZJ9 which was the light group. The mirror light option wasn't available separately on 69 fullsize. This option group included on 2+2's the following:
under dash lights (standard on rag tops)
ash tray light
underhood light
map light (the light in discussion on the Inside Rear View Mirror
dash warning lights (low fuel, seat belts, lights on)
Here is a pic of the dash cluster with the three warning lights, they aren't illuminated in the pic but they are the square box just to the left and the two boxes just to the right of the odometer. The chrome knob is for the separate speed warning option.
Thanks John I noticed my wire that runs to the map light looks really bad all the way down under dash so would have to replace that, your heater switch controls fan ect is there anywhere I guy could find that stick on chrome that says on ,off, fan ect .. hope you can figure out what the heck I am trying to get at ,,my data sheet says I have UF1, map light,U26 lamp underhood, U28 ashtray lamp,U80 aux rear speaker,ZH1 lighting group,ect No ZJ 9 on the sheet
ZH1 must be the same group as ZJ9, Is your car a coupe or ragtop?
I Would make a new wire from the fuseblock to the mirror. You can reuse those packard style plastic connector housings. There is usually two wires, one from the fuseblock to about a foot from the mirror and then the short harness to the mirror itself. Canadian cars had the mirror going into the ACC plug in the fuseblock so the light can only be used with the key in accessory or run, US cars had it in the BAT plug so you can use it without the key, handy but the risk is that you run down the battery if you leave it on.
As for the heater control panel decal I'm not aware of anyone redoing them, the lettering is actually cutouts in the aluminum decal so they illuminate at night. Best chance is to find a good used or NOS control head, the decal was never serviced separately.