Power window circuit 1975 - What is this

Power windows decided not to work for no reason I am aware of. In tracing the wiring, and trouble shooting the problem, I found this black junction box in the car, but it does not show on any diagram or schematic I looked at.

The RED wire goes to the LPS in the fuse panel.

The BROWN wire goes to IGN in the panel, then pigtails with the PINK/BLK and goes to the relay. I have continuity but no voltage.

I have never seen any indication in any diagram or schematic that this should be in the power window circuit. Unless I am missing something.

What is it ???

Thanks for any help.

A buzzer of some sort?

http://patent.ipexl.com/US/3768158.html

http://67-72chevytrucks.com/vboard/showthread.php?t=501193

Thanks for that info. Seems like that might be the case, but my key-in-ignition, and seat belt buzzers both work with this out of the picture.

And why the heck doesn't it appear in any schematics?
Unless I'm missing something ...


I by-passed the relay, and wired directly to the wire exiting the relay which feeds the switches and the window motors now work. I've read conflicting opinions on whether this relay is needed. Later C3 models have the same components in the PW circuit, and no relay.

I know a relay's intended purpose, and it's only about $25 or so, but my thought is if it's not crucial to a function, it's becomes just another unnecessary part to go wrong.

I appreciate suggestions and thoughts about doing away with the relay. Thanks a lot.

I don't know if the '75 came with that relay from the factory. The relay is used to keep the current draw through the switch low and at a manageable level. Removing the relay may eventually burn out the window switch. I think I would replace it just to be on the safe side.

LEJ ZO6 said:

I don't know if the '75 came with that relay from the factory. The relay is used to keep the current draw through the switch low and at a manageable level. Removing the relay may eventually burn out the window switch. I think I would replace it just to be on the safe side.

Click to expand...

Thanks. That is a relay from the factory. I probably will replace it. I am curious because the wires in/out of the switches is 12 ga., and is the same in later models that don't have the relay. All things considered, the wiring and components are the same in later year models, with the exception of the relay.

UPDATE==> This is a headlight warning buzzer

Made to buzz if the headlight is on and the doors are closed.
Why it's in the PW circuit I can only assume because the PW relay and this buzzer have to share the IGN cavity of the fuse panel.

My guess is that three conditions might have to be present for the buzzer to sound an alarm:

1. Headlights on
2. Doors closed
3. Ignition off

That makes sense.

Any ideas as to why the "IGN" is voltage dead with the key in the on position?