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Discussion Starter · #1 ·
I am installing an aftermarket backup camera. The camera and monitor have trigger wires as well as the positive and negative. In order to get this working properly, i would need to attach the trigger wire with the revers lights.

Does anyone know what colour is the reverse light wire? Also, would i need a relay for this?

I would appreciate the help!
 

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If it is me, I would use a relay and wire the relay to the reverse gear switch S_RFS line.

You may be able to get away by just connecting it to the reverse lights wire directly or with a relay.
But there is 2 issues
- the light module checks if the bulb is good with a low voltage (not sure, maybe 5V) periodic signal. What would the camera react to this low voltage? If it does turn on, it would come on every time the light module is checking the bulb
- would the bulb check be messed up by the extra current the camera or the relay draws?

you can give it a try, it will not damage anything. you may get error messages
 

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Discussion Starter · #5 ·
If it is me, I would use a relay and wire the relay to the reverse gear switch S_RFS line.

You may be able to get away by just connecting it to the reverse lights wire directly or with a relay.
But there is 2 issues
- the light module checks if the bulb is good with a low voltage (not sure, maybe 5V) periodic signal. What would the camera react to this low voltage? If it does turn on, it would come on every time the light module is checking the bulb
- would the bulb check be messed up by the extra current the camera or the relay draws?

you can give it a try, it will not damage anything. you may get error messages
I haven't even thought about that...

So if i decide to connect the camera relay to the gear switch, where and what colour would it be? Any knowledge of other threads on how to access this wire?
 

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The S_RFS wire goes from the FEM module in the driver's foot well to the transmission. You could get to it at the FEM module, lead the wire under the left doors' sills, go through the rubber sleeve of the trunk lid. Quite a lot of work but doable.

Try connecting the camera directly to the reverse lights wires first and see what happens. A relay draws more power than the camera itself so there is no point of connecting a relay to the reverse lights lines. If this doesn't work, use the bulletproof method above, connecting a relay to the S_RFS line. (no need for a relay there either, you can connect the camera's ground wire straight to the S_RFS).
 

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Discussion Starter · #8 ·
The S_RFS wire goes from the FEM module in the driver's foot well to the transmission. You could get to it at the FEM module, lead the wire under the left doors' sills, go through the rubber sleeve of the trunk lid. Quite a lot of work but doable.

Try connecting the camera directly to the reverse lights wires first and see what happens. A relay draws more power than the camera itself so there is no point of connecting a relay to the reverse lights lines. If this doesn't work, use the bulletproof method above, connecting a relay to the S_RFS line. (no need for a relay there either, you can connect the camera's ground wire straight to the S_RFS).
I would rather connect the trigger wire to the revers light as opposed to the reverse gear switch. My only concern is getting an error message on my dash if i do so.

After research, It appears that a relay would do the trick.

I am hoping that this would work:

Plan Floor plan Technical drawing Drawing Diagram
 

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I would rather connect the trigger wire to the revers light as opposed to the reverse gear switch. My only concern is getting an error message on my dash if i do so.

After research, It appears that a relay would do the trick.

I am hoping that this would work:

View attachment 753369
I would totally skip the relay in this case. The coil in the relay draws current that can mess up the reverse light bulb check. The input signal to the camera has high impedance, invisible to the light control module. The only question is how the camera will respond to the the light check period. The relay switches on at as low as 6-7V. The threshold voltage for the camera input is either half the VDD that is 14V/2 = 7V or less.

If the light check messes up the system, you can add an RC filter.
 

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Discussion Starter · #10 ·
I would totally skip the relay in this case. The coil in the relay draws current that can mess up the reverse light bulb check. The input signal to the camera has high impedance, invisible to the light control module. The only question is how the camera will respond to the the light check period. The relay switches on at as low as 6-7V. The threshold voltage for the camera input is either half the VDD that is 14V/2 = 7V or less.

If the light check messes up the system, you can add an RC filter.
Are you referring to a filter rectifier?

Would it be possible to advise how this is circuited?

I appreciate the help :beerchug:
 

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If it is me, I would use a relay and wire the relay to the reverse gear switch S_RFS line.

You may be able to get away by just connecting it to the reverse lights wire directly or with a relay.
But there is 2 issues
  • the light module checks if the bulb is good with a low voltage (not sure, maybe 5V) periodic signal. What would the camera react to this low voltage? If it does turn on, it would come on every time the light module is checking the bulb
  • would the bulb check be messed up by the extra current the camera or the relay draws?

you can give it a try, it will not damage anything. you may get error messages
Hi
This is exactly what I am experiencing with my aftermarket camera on a 2002 325i. I have attached the red trigger wire to the back up light in the trunk. Everything works as it should but once i turn my headlights on (which obviously includes my taillights) the back up camera will randomly activate itself whether I have the screen in power save mode or have the front camera on. It is very annoying as I prefer to have the screen in power save mode (sleep mode) and use the screen as a mirror but still have it recording. I thought it must be a check of the bulb as you stated and am relieved to hear you say the same thing. The problem for me now is where then do I wire the red trigger wire to avoid this?
Thanks for reading
 

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Hi
This is exactly what I am experiencing with my aftermarket camera on a 2002 325i. I have attached the red trigger wire to the back up light in the trunk. Everything works as it should but once i turn my headlights on (which obviously includes my taillights) the back up camera will randomly activate itself whether I have the screen in power save mode or have the front camera on. It is very annoying as I prefer to have the screen in power save mode (sleep mode) and use the screen as a mirror but still have it recording. I thought it must be a check of the bulb as you stated and am relieved to hear you say the same thing. The problem for me now is where then do I wire the red trigger wire to avoid this?
Thanks for reading
Your backup light turns on when you turn on your headlights?

You are supposed to wire the trigger to the reverse light switch circuit, not to the lamp. Depending on how you access the circuitry, typically the positive trigger to the relay output, whereas the negative trigger can be spliced to the relay trigger.
 

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The trigger wire is attached to the live wire feeding into the reverse bulb. The dash cam works perfectly when i do not have my headlights/tailights turned on. When i turn my headlights/taillights on it affects the dash cam screen by randomly waking it up and activating the rear camera with the red green yellow parking assist lines
 

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The trigger wire is attached to the live wire feeding into the reverse bulb. The dash cam works perfectly when i do not have my headlights/tailights turned on. When i turn my headlights/taillights on it affects the dash cam screen by randomly waking it up and activating the rear camera with the red green yellow parking assist lines
Get it wired properly. Then come back.
 

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Well aren’t you a pleasant fellow. That is the reason I here, to get help with the wiring. I have wired it to the reverse light as instructed and it is not working nearly as well as it should
I said specifically, your trigger needs to go to the switch circuit, read that again, circuit. Not to the lamp. It may sound like the circuitry and the lamp is the same thing, but they are not. The circuitry is within the fuse boxes and relays area. They will behave differently. When you shift into reverse, it triggers a reverse switch, which enables the reverse light, reverse camera, etc, among other things. THAT is where you need to get your signal.

Don't ever tap into bulb wiring, even if the instructions say so. It will mess with the bulb check circuitry. The aftermarket manufacturer will take the easy way out, for liability purposes. Don't believe me? Can't help you then. I thought I was clear. Apparently not. You ask for help; you receive it. It's up to you as to how you take it.
 

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I said specifically, your trigger needs to go to the switch circuit, read that again, circuit. Not to the lamp. It may sound like the circuitry and the lamp is the same thing, but they are not. The circuitry is within the fuse boxes and relays area. They will behave differently. When you shift into reverse, it triggers a reverse switch, which enables the reverse light, reverse camera, etc, among other things. THAT is where you need to get your signal.

Don't ever tap into bulb wiring, even if the instructions say so. It will mess with the bulb check circuitry. The aftermarket manufacturer will take the easy way out, for liability purposes. Don't believe me? Can't help you then. I thought I was clear. Apparently not. You ask for help; you receive it. It's up to you as to how you take it.
 
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