Use Relay to Disconnect Ground

I have a switch panel that has a relay board.
That relay board only has 12v outputs.

2 outputs are available. One is for on/off, the other is to select high-beam or low-beam.

The switches only have the ability of either momentary on/off or constant on/off.

I have 4 spst relays in a circuit with 2 functions (high-beam & low-beam)

I have 2 latching relays to control the 4 spst relays. The function is switching two relays on & the other two off.

When the latching relays are energized it energizes the 2 spst relays.

Considering the switches only output is 12v+ would I be able to use another relay to control the ground switching of the latching relays? Or Can the latching relays use a switch on the 56/30 terminals?

I am under the impression that latching relays may only use ground switching for the S terminal.

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built not bought

It seems like a lot of relays... And maybe unnecessary relays controlling other relays - maybe the controlling relays can be consolidated?

WRT relay designations:
56 = spot light
56a = headlight high beam and indicator light
56b = low beam
... not that relays have to control those items - they can control anything.

A hi/lo beam (and any) latching relay may well use GND to change state though I know +12V switched versions exist.
If they use electronic latching circuits (eg, the SAAB red hi/lo beam relay), then either could be used - eg, a GND switch with a pull-up resistor to +12V, or a +12V switch with a pull-down resistor to GND.

And other outputs may be used - eg, grounding a relay coil thru a bulb means it is GND except when that bulb is on (ie, +12V - assuming it's a +12V switched bulb).


Ground can be used as a disabling function, but care must be taken that there is no alternate GND path - ie, that another +12V source is not instead connected to GND, then the relay coils (or loads) are in series and may energise.
And example of alternate GND paths is a dual filament stop/tail bulb. If its GND is broken, then the tail will be on whenever tail power or stop power is on, but if both are on no light will be on. That's the classic "bad GND" taillight where normal tail lights seem okay until the brake is applied (then they extinguish), and the high-wattage stop bulb never illuminates - only the dimmer tail filament.
(And for loads like EMSs, audio & amps etc, GND should never be broken. Alternate GNDs will often damage or fry circuits!)


Much depends on what you are intending, both behavior and circuit wise. The pneumatics controller wiring thread is where an initial drawing (else clear description) plus later info resulted in a far simpler solution.

should only need to use one latching relay. the design of the relay is to have the 'S' terminal be a low current negative control.
term 30 is battery power, term 56 would be positive power from the headlight switch. 56a and 56b obviously are the outputs. you might be able to open the relay and isolate the coil from the contacts, but an additional wire would be needed if the flash-to-pass operation was still desired...assuming the correct VW relay was chosen. given that, just use a relay to convert your hi-lo beam select to negative.

ah yes, multitasking...OS you've beaten me again.

Mods, cynical sarcasm alert.
This and the gentleman's previous thread post has me like this
Please remember KISS rules apply here.
One ground.
One on off 1 on both on switch and two relays (hi and lo).
2 x 100 watt bulbs will draw   >20 amps with losses.


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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.

Howie 2, I am not sure I understand your comment.

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built not bought

KISS = Keep It Simple and Stupid.
What you are trying to achieve is over complicated and bound to fail.
Here's a simple "ultimate" headlight circuit.
One switch, latching off/on/on, one momentary switch, 3 diodes and 2 relays.
Like so, one = Lo beam, on 2 Hi and Lo plus the momentary for headlight flash.
D2C_headlights.bmp

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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.

I specified details:
my existing membrane switch panel has only positive outputs.
My membrane switch panel has two functions. On & Off.
My membrane switch panel is capable of momentary or continues.

Can you modify your circuit to fit?

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built not bought

is it an ARC control panel?

Well now, doesn't it help when you list what you trying to do this with.

I specified details:
my existing membrane switch panel has only positive outputs.
My membrane switch panel has two functions. On & Off.
My membrane switch panel is capable of momentary or continues.

jkxmlr wrote:

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Well now, doesn't it help when you list what you trying to do this with.

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What I meant.

Yes it is arc autorod controls

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built not bought

Please look:
https://blog.dirtyracingandrods.com/

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built not bought