[CanadianBacon]

Hi working on a 68 impala 2dr fastback i recently picked up. I am replacing some of the electrical switches and noticed under the dash on left of the steering column there is a knob and rotary switch. There are two wires which go into the harness I cant continue to trace unless I start ripping. Knob is similar to a vent knob. However it does nothing. This is mounted under the dash, knob facing to floor. I am suspecting it maybe something to do with heating, rear defrost ??, if so since removed if it there was. Not having much luck finding info on it. Asked a few pld school chevy friends as well but no avail. Appreciate anyone's insight.

 

[Jynx]

Post a photo, someone will know.

 

[67ImpalaSSConv]

If it's mounted underneath the dash instead on the face it is probably something aftermarket someone added at one point. Maybe they were replacing a broken switch or knob that didn't work.

I found an old light pull chain type switch in my 67 under the dash that someone used to replace the old vaccum style switch that broke, looked to be decades old.

 

[Pete From Hill Country]

Okay this was many years ago, but I had a 68 SS with that undermount rotary switch. If memory serves, that might be for the rear window defroster. Do you have a vent in the deck lid with a blower motor? You'd see the motor from inside of the trunk.

 

[CanadianBacon]

Here is a picture of the button, thanks folks.

 

[62BillT]

It does look original. If no one can identify it, the best thing to do is to list all the Options the car has. It is most likely a Switch for one of them.

Or check into an original Owners Manual that should show it.

Keep us posted on it.

 

[Pete From Hill Country]

Here is a picture of the button, thanks folks.

Okay, my Super Sport had that. On my car, it was a two speed knob for a rear defroster. Turn it one way for high speed and the other for low. Does your rear deck have a louvered grill off to one side? That would be where the blower motor was. It might have been removed or replaced (speakers?), but the wiring might still be there. Take a look and see if you have any wires that are not accounted for back there.

 

[CanadianBacon]

Rear defrost was my weak assumption. And there seems to be a stop in the switch as you indicated so all likely this is what is was at some point. There is no evidence of a rear defrost system, as the top behind the back seat was replaced prior to my purchase, no speaker holes or any penetrations. I looked for wires in the back but only speaker wires and no heavier wires for a heater fan or such. I can probably conclude this is what is was for before the last mods.

 

[Pete From Hill Country]

There might be some old wiring back in the trunk someplace that you could run some 12 volt through to test it. On my SS, the defroster was on the one side of the rear deck - don't quite remember which.

 

[62BillT]

Although not always easy to find, have you ever tried to find the Build Sheet of the car?

 

[CanadianBacon]

Good ideas I see if I can find.

 

[mls68z28]

Hi,if you are not going use the switch I would like to buy it,Thanks Mitchell