2nd Gen Non-Engine/Transmission Mystery switch wiring ?

[Hummin Cummins]

Instead of a standard mystery switch, I installed a floor dimmer switch to force unlocking of my TC.



I want to put a small LED light in the dash to be lit when the switch is in the normal factory mode. (wife proofing)



Am I correct in thinking that since that is a ground circut, I can simply put power to the LED light and tap the ground wire for the light into the floor switch, hence completing the circut to light the light when the TC is locked and light goes out when I break the ground?



Chris

 

[Whitmore]

Sounds right to me, you already had it figgered and you are just testin us... ... ... ... ... eh



cheers, Kevin

 

[illflem]

Not positive but think you may have to add a diode so power doesn't feed though the light basically bypassing your switch.

 

[Chipstien]

Illflem, I thought a LED was a diode hence "light emitting diode". Have I been wrong for all this time.

 

[illflem]

Chip, you're right, that's why I said I wasn't positive, sort of hoping someone who knew more about it would pipe in.

I know a regular bulb can cause problems in an application like this.

 

[Hummin Cummins]

Not testing you.



illflem, Thats what I was worried about. Not really the power feeding through and bypassing the switch, but more like power feeding through and cooking something in the PCM.



It seems like a silly waste of time, but even I sometimes forget when I park the truck what position the switch was in the last time I drove it

 

[illflem]

Easy way to avoid any problem would be to use a double pole switch, use one side to switch the trans and the other to switch the light. The light would be on it's own circuit then. In fact the light for OD off is rigged this way.

 

[nwinters]

I think a dual pole switch is the only way to go. I tried to do the same thing with a switched ground, the LED would go on, but the thing I wanted to turn on wasn't activating. The LED, acting as a diode, doesn't let the device you are switching see the ground (I think).



Nate

 

[Karl2500]

If you use a loose led remember to use the proper resistor in line with the led. Most don't like more than 20-30 ma. If you get a pre-wired one it should have a resistor in it.

 

[Hummin Cummins]

I'm guessing that since there is a third tab for a wire on this floor dimmer switch that it could be used for the led? I would think thats how they get the high beam indicator to light in the dashboard. (its a 5$ dimmer switch for a ford)



I guess I need to get my meter out and probe a little.

Keep the ideas coming. I can do straight up auto wiring, but when we get into this funky resistor diode thingamabobbers, i get a headache.

Chris

 

[illflem]

I had an interesting experience with a led. I needed a pilot light for a 12 volt DC cooling fan on a piece of hydraulic equipment, scavenged an led off a broken battery charger wired it in so that it drew it's power off the fan's power. Worked great except the led lit up even when the fan wasn't running just by the wind turning the fan. The electric motor acted as a generator providing enough juice to light the led. Replaced the led with a regular bulb, no more problem.