Mysterious switch...

[tjb0274]

Had a good forage behind the dashboard of my "bitsa" S4 today, tracking down some electrical gremlins as I get it ready for registration.

One surprise was a momentary-action toggle switch that was hanging free, but tucked up into the loom so that it didn't hang below the dash. It's at the end of two blue/purple wires that I haven't yet traced, but I was wondering if anyone has thoughts on what it could be for... It doesn't seem to do anything as far as I can tell, and the only momentary-action switches I can think of on an S4 are the window switches. which need to have two "on" positions, not just one.

[gjz30075]

The other one, at least the one I have on my Federal Sprint, is the 'brake' warning light test switch. It's a black
plastic, push button type that got mounted in the under dash valance.

[types26/36]

It has not got an electric fuel pump as well as the mechanical one has it ? sometimes people fit them just to prime the carbs after standing a while.
.......or even an electric antenna ?

[chickenstock10k]

I have a similar switch in my plus 2. When I push it, it lights up the brake failure light on the dash. I could never really figure out what it was for though. Was it really intended just to test that the brake light works?

[stugilmour]

I have a similar switch in my plus 2. When I push it, it lights up the brake failure light on the dash. I could never really figure out what it was for though. Was it really intended just to test that the brake light works?

I think that was the case. I expect the Federal regulations required a way to test the warming light, and this was the easiest way to meet the regs without adding a relay that would light up the fail light prior to the engine starting or some such.

Does your S4 have the dual brake circuit? The warning light we have in the Federal Plus 2 is triggered by failure of one side of the duel brakes.

Stu

[gjz30075]

Dual circuit in the Sprint. The light is wired to the cap of the Sovy can. The float in the can would drop
with a drop in fluid, from either circuit, triggering the light.

[tjb0274]

Thanks for all the suggestions and thoughts

Found out what it is yesterday - there was a bad connection and when that was fixed the mysterious switch turned out to be for the wipers - someone's idea for a driver-controlled intermittent, I guess.

The dash looks pretty new, so guessing the switch was mounted in a previous dash and then just left hanging when the dash was replaced

One of a number of things I'm sorting out with the wiring.

[The Veg]

I think that was the case. I expect the Federal regulations required a way to test the warming light, and this was the easiest way to meet the regs without adding a relay that would light up the fail light prior to the engine starting or some such.

I think that is correct. I once had a '73 Super Beetle in which I recall something similar.