TECH: Switch for Reverse Indiglo Gauges?

[FLAWLESS]

I have installed my new Reverse Indiglos on a 12v switch so I can leave them on even when the car is off for show etc.
I had my old standard indiglo's wired to the parking lights so they automatically came on.

Is there a way that I can have them ALWAYS come on with the parking lights, but still be able to flip my switch and juice them up when the car's off?

I was thinking of running a wire to the 12v for the gauges -from the parking lights (+) after the switch. But MY CONCERN is that power will back feed into the parking lights circuit when the car is off and the gauges are on. Should I be using a RESISTOR or RELAY in some capacity?

[fritz_269]

You just need a simple switch called a 'Single Pole Double Throw' (SPDT)

This kind of switch has three terminals. Attach the one in the center to your indiglo power wire; one side to the +12V; and the other side to the parking lights.

When the switch is in one position, the indiglos will be attached to the +12V; with the switch in the other position, the indiglos will be attached to the parking lights.

Make sure that there is a fuse somewhere between the +12V and the indiglos though! There should be some kind of always-on accessory fuse already in your under-dash fuse box. Take the +12V wire from there.

Simple.

Here's a picture of a SPDT switch - notice the three terminals - this one would work but would be WAY overkill You could find a nice sized toggle or rocker switch at your local radio-shack.

[Someguy]

I think we have that exact same switch on the backside of one of our radar system's racks.

[FLAWLESS]

YEAH FRITZ U are the best. I knew there was a simple solution! Thanks, I'm gonna wire it tonight and I'll let you know how it works.

-Anth

[FLAWLESS]

Hey Fritz one more Q then I'll leave you alone.

What rating fuse should I use for this application...and where should I fuse it...from the switch to the gauges right? Thanks man.

[crxlvr]

sorry im not fritz, but id go 20A fuse to be safe.

[fritz_269]

I doubt the gauges take 20A to light... a 5 amp 'slo-blo' fuse would probably be ideal, but anywhere from 2-20 amps is probably fine. The instructions with the indiglos might suggest their mfg. recommended fuse rating as well. You just want to make sure that if your wiring or the indiglo gauges short out, that you don't heat up a wire & start a fire.

the wiring would probably go like this (pardon the crappy ascii art):

+---accessory----5Afuse------*
                              \
                     switch->  *-------------indiglopower+

+---parkinglights------------*

The parking lights already have their own fuse, so don't worry too much about that wire. If you look at the fuse box under your dash, you might find that there is an unused fused accessory terminal, just waiting for you to use it. That way you wouldn't have to add another fuse and holder. Note that there are two kinds of accessory terminals - one which is always-on, and one which is switched by the ignition key; you obviously want the always-on variety.

Good luck.

PS> Make sure the switch you buy is rated for 5A @ 12VDC or higher.

[FLAWLESS]

I was gonna wire it like this. (The switch I got has 3 terminals, ON/OFF/ON.)

12V+ constant from fuse panel to ON
12v+ TO indiglos to OFF (with fuse on this wire)
12v+ from parking lights to ON

Am I on the right track?

[FLAWLESS]

I got the switch from Radio Shack and wired it up. Works like a charm. Looks ugly (it's one of those long black toggles) but it works! Thanks to everyone who gave me input.