Car Electrical Help: Get Tutoring Now!

Good evening, everyone!

Okay, I'll admit it right away: automotive electrical systems are definitely not my area of expertise, and it's been about 10 years since I last dealt with them. So, I was hoping you might be able to help me out without me having to spend hours racking my brain and potentially messing something up in the process.

Here's the translation:

"The issue is this: I have a universal radio remote control for switching 12V devices. It naturally has input terminals for positive (red) and ground (black), and output terminals that switch positive (yellow) and ground (black)."
Now comes the tricky part. I don't want to use this remote control to switch any devices, but rather to control a ground wire, which wouldn't be feasible in that way.
Here's my question: Can I use this remote control circuit to control a relay in such a way that it switches a corresponding contact to ground?
If so, please tell me how I should connect it.

Thank you in advance.

Best, Tobi.

Hello, if I understand the question correctly, you want to pass a switched 12-volt ground connection through the remote control.
If the outputs, yellow (+) and black (-), provide 12 volts with a corresponding current when switched, and you have a 12-volt relay where 85 and 86 are the coil windings and the switched contact is connected to ground (31), then when the relay is energized, it connects ground to, for example, 87, and you have the switched ground contact.
However, your power supply needs to be able to handle the coil current. You can easily calculate this based on the measured resistance of the winding.

Most of the remote controls I know have their own 12V and ground connections. Could it be that the red wire is simply switched to yellow, and ground is connected to ground? In that case, you could simply use the red and yellow connections to switch the ground. But this would only work if the signal is directly switched through, independent of the remote control's internal electronics!

Hello!

Thank you in advance for your responses.
@ Rubberduck
The remote control circuit definitely connects the + and - (ground) to the same trace on the circuit board, meaning the - (ground) input and output are the same. I traced it on the board, and using an ohmmeter, you always get a connection.
I'll attach a picture of the circuit board; maybe you can tell me if it can be repurposed to switch the ground connection.

@ Partial exam.
How do you mean that the remote control needs to be able to withstand the coil current?

Thank you.

Best, Tobi.

Considering everything, I assume the CR780CF is also a standard relay, right?
It should actually be possible to detach this component from the circuit board and then reconnect it via cables in such a way that it creates a ground connection instead of a positive connection, right?
But, as I said, these are just the thoughts of a complete amateur, and the actual implementation always seems to be the problem.

The issue with the coil current is irrelevant since you have a built-in relay for which the circuit is designed.
So, you just need to disconnect the relay input that, according to you, provides 12V positive, and then connect it to ground. This will cause the ground to be connected through the closed contact in the relay.
However, there must also be no connection between the REL terminal and the positive terminal.
The black cap can certainly be removed to rule that out.

If you also post a picture of the underside, we should be able to help you...

Good evening, everyone.

I thank you all for your help, but the issue has now resolved itself. While I was dealing with all the tangled wires, the ground cable slipped from my hand and accidentally touched a 12V+ point where I had everything connected for testing. This caused the circuit board to react negatively, and it immediately showed its displeasure. In a fraction of a second, two of the copper traces shorted out, and it started to smell a bit suspicious.
Good thing that this thing only cost me just under 10 euros on eBay.
Does anyone have any other good ideas on how I can remotely control the switching of a main power line in a cost-effective way?
As I said, thank you, and have a good evening.

Best, Tobi.