Community Forums

randco · 06-28-2012, 02:53 PM

Quote:

Originally Posted by 87Rockwood

No the switch is on the ground side. Take the wire off the door switch and ground it. Look my interior lights came on. Take the wire off the oil pressure switch and ground it ,oh look my "oil" light is on.

If you take either wire off of the door switch and ground it you will probably blow a fuse.

randco · 06-28-2012, 02:56 PM

Quote:

Originally Posted by JimM68

The most common is the courtesy lights on car doors.
They run hot to the lamps, and a single wire to the pin switches in the doors.

Door open equals pin hits ground equals light

A lot of circuits switch the ground side. It doesn't matter a whit to the load, and can often make things easier, or cheaper on the manufacturer.

Wow, this is news to me. I guess I am not to old to learn something.

87Rockwood · 06-28-2012, 02:56 PM

Quote:

Originally Posted by randco

If you take either wire off of the door switch and ground it you will probably blow a fuse.

I only find one wire. If I unplug the wire from the switch and ground it my lights turn on. What part of this do you not understand?

randco · 06-28-2012, 02:58 PM

Quote:

Originally Posted by 87Rockwood

I only find one wire. If I unplug the wire from the switch and ground it my lights turn on. What part of this do you not understand?

Let's try not to be condescending. JimM explained it. I never knew they wired auto's like this.

87Rockwood · 06-28-2012, 03:06 PM

I guess I do not understand-I gave you the same "proof" 3 times. and You still would not see it. Then someone comes along and gives you the same answer/proof same example and his you believe!

randco · 06-28-2012, 03:09 PM

Quote:

Originally Posted by 87Rockwood

I guess I do not understand-I gave you the same "proof" 3 times. and You still would not see it. Then someone comes along and gives you the same answer/proof same example and his you believe!

I suppose he explained it a little better than you did.

Dunner · 06-28-2012, 04:01 PM

Quote:

Originally Posted by randco

I have never seen any switches that were wired in series with ground or neutral.

Quote:

Originally Posted by Dunner

Here's a good example of grounding a device. My Dodge Ram ECU applies a ground(switch) to the sensors, injectors, etc to monitor and actuate them. They do this so if you accidentally ground a sensor wire or a pin on the ECU, it doesn't damage it.

Quote:

Originally Posted by randco

I think that gounding a device is a little different than placing a switch in a ground wire in a DC circuit or in a neutral in a 120V circuit.

So, an electronic switch is different than a mechanical switch? Is a door light or oil pressure sensor not a device? Plus all the other examples.

Quote:

Originally Posted by BCooke

.....latching relays......

Those work by applying a +12V to latch and –12V to un-latch.

randco · 06-28-2012, 04:23 PM

Okay, I throw in the towel. Seems a lot of you guys know much more about these DC circuits than I do. Like I said earlier, one is never to old to learn.

Dunner · 06-28-2012, 04:44 PM

Just because you haven't seen them, doesn't mean the rest of us are wrong.

I know it's not common or even preferred, but I've seen enough to know they do exist.

randco · 06-28-2012, 04:56 PM

Quote:

Originally Posted by Dunner

So, an electronic switch is different than a mechanical switch? Is a door light or oil pressure sensor not a device? Plus all the other examples.

Those work by applying a +12V to latch and –12V to un-latch.

I'm not sure about your last statement.

This is the typical latching relay circuit that I know.

randco · 06-28-2012, 04:59 PM

Quote:

Originally Posted by Dunner

Just because you haven't seen them, doesn't mean the rest of us are wrong.

I know it's not common or even preferred, but I've seen enough to know they do exist.

Call me a skeptic...

Dunner · 06-28-2012, 05:15 PM

That was the Reader's Digest version. Actually, there are two types of latching relays. Single coil that reversing the polarity reverses the relay and double coil that change which coil gets the voltage.

Dunner · 06-28-2012, 05:20 PM

1)Reverse the current through the coil of a single-coil latching relay. This must be done in the control circuit in the appliance containing the relay.

2)Apply electrical current to the second coil of a two-coil latching relay. In this case, application of current to the first coil operates the relay, and application of electricity to the second coil resets the relay.

The current is only supplied momentarily to either latch or un-latch the relay.

Sundancer268 · 06-28-2012, 05:49 PM

Quote:

Originally Posted by randco

I an interested, can you name a few? Not something like a "kill switch" that is a "short to ground".

The Dome light in most cars are wired hot to the light and ground through the switches. This makes it easy to use a self grounding switch in the door jams on the older vehicles. The Parking Brake warning light was also wired this way in several Plymouth's and Fords as well as my IHC Scout II. A lot of the newer cars use the ground wire for computer switches also.