heated mirrors wiring , switch problem

I've installed 4 heated mirrors on my LLV (same thing as USPS mail carriers drive) and got everything wired up and working. Unfortunately I discovered that even with the power off, the battery drained. This isn't my diagram, but mine is pretty much wired up similar to this:
https://www.brick-yard.co.uk/forum/up...irror_diag.jpg

I'm not using an illuminated switch, I had an extra 50 amp SPST toggle, so using that with power directly from the battery, not ignition-on to the switch. Switch like this:
https://www.socalsac.com/sites/defaul...100_2518@0.JPG

Here's my question, should the switch be grounded by the mounting? I have the mirrors' relay hooked up to one prong and the battery power to the other prong. The switch was mounted previously for operating strobe lights and was going through a metal bracket in the plastic dash (thought the bracket was just holding the dash together but might have been there for grounding?)Where I have the switch mounted now doesn't have any metal, so if it needs grounding, I can run a grounding cable to put on the switch mount.

Any suggestions or tips are greatly appreciated!

Luckily I found your s10forum.com post. You can't merely cut&paste screen text... (eg - look at your links).


The diagram is for an illuminated switch.
The switch you picture might be SPDT two way (3 terminal) though its on-off label suggests it's a 2 terminal SPST switch.
If you were to ground the 3rd terminal in an SPDT, you would short the switch's +12V (battery) feed to GND when switched to that position and hence blow whatever fuse is involved.

That switch's metal jacket is insulated from the switch terminals. Its grounding has no effect.


If you leave the switch in the ON position, the relay will remain energised hence its coil and more importantly the mirror heaters will remain on and thereby flattening your battery.


Stick to the diagram's wiring - namely having the switch powered by IGN +12V. It does not have to be an illuminated switch though I do suggest that indication is given when it is on.   


And a 50A switch is totally unnecessary. A 1A rated switch is more than enough, probably much less. (It only needs to handle the current of the relay coil and any switched bulb etc.)

First off, thanks for the heads up about the links. Here are the correct ones:
Wiring: https://www.brick-yard.co.uk/forum/uploads/6278/heated_mirror_diag.jpg

Switch: https://www.socalsac.com/sites/default/files/100_2518@0.JPG

My switch is definitely a 2-terminal SPST. Here is how my setup differs: I run the 4 positive wires from the mirrors to a 4-switch panel (so each mirror and be turned on and off individually) and the main positive wire for that panel runs to the relay. I can tell when the main battery switch (the 50 amp) is off, as when I try to throw one of the mirror switches, it doesn't get any power. All the mirror grounds, switch panel ground and relay ground are grounded to a single terminal ground that's wired to the battery ground. Here's the ground terminal I'm using:
https://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productid=17184&catalogId=10001&langId=-1&storeId=11151&storeNum=50523&subdeptNum=50549&classNum=50553#.UP15wPI8Eg8

I'm just baffled right now as to what's causing the battery to drain when the main power switch is shut off.

Bet you're using a 5 terminal relay and you've wired it to 87a instead of 87.
Here's the correct diagram showing one switch and one relay.*
Have you measured the current draw for all those mirrors. Bet it's about 25 amps in total, not 50.heated_mirror.bmp
* Also shown, LED and diode across the relay coil, 1N4004, band towards 86.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

It's in the 87. I think my problem might not have been my mirrors at all. When dealing with all of the connections at the battery terminals, I forgot to reinstall the ground for my front fog lights. Right now I have a fully charged battery with only the main cables and my mirrors hooked up to it. If the battery doesn't drain, that unconnected fog light ground was most likely the culprit (that's what I'd get for hooking up cables in the dark. Ha!)

Forgetting to re-install the grounds would simply make them not work. Nothing to do with battery drain.
Wire the switches through the ignition and use single pole switches as Oldie and I suggested.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Did as was suggested (added an add-a-circuit fuse tap to an ignition-on accessory fuse versus tapping into the wiring and bought a new illuminated SPST switch) and no more battery drain.

Good to hear.

Changing original circuits needs thought, in this case being able to leave the circuit on when the IGN is off.

The lack of illumination may be trivial, but may prevent mirror heater burnout and improve fuel economy.