Adding a basic relay for add on device not wanting to upset canbus?

[Droverunner]

Finally getting round to sorting out an aftermarket stand-alone reversing camera/monitor. Seems the best way to wire it is to take a feed from the reverse light one side for both camera and monitor but I'm assuming that will play up the bulb warning and annoy me. So I'd wondered about putting a relay in so the reverse light feed was just a trigger to switch the relay to feed from a power source like the cigar lighter or one of the other 12v sockets.

Haven't needed to fit a relay since the heady 70s days of spotlights and air horns.

Will this work on the Viano and not upset anything?

BTW rumour has it there is a spare yellow reverse trigger wire behind the command unit so will seek that out first.

 

[supernoodle]

Make sure the relay has some form of suppressor built in, like a diode or resistor. Most will have, but just check first.




I know the bulb monitor complains if the current draw is too low, not sure if complains if too high. If it does you can buy a relay module like this that has an opto isolator, that should lower current draw and eliminate any back EMF problems like a relay.

Opto isolator

 

[M80]

The worst you would get by upsetting the reverse loading is "Reverse Lights" when in reverse.
The SAM will record the code.
The dash will show '1 Fault' until the ignition is cycled.

I get this every time I select reverse due to reverse cam and LED reverse lamps (the 7 watt x2 lamps being the 'fault'), I'm not bothered by it as I'm not looking a the dash when in reverse anyway.

But I would be surprised if it would see the extra minimal load as a fault, so maybe try it before fitting a relay.

Are you still running Comand?

 

[KennyN]

When i fitted a RVC to my W219 i had to use a "clean" supply for the camera as there was interference on the screen when the car was running , fine when the ignition was on , but not when running.

I used the reversing light supply to switch the relay and a (fused) clean supply straight from the battery , there were no issues with any lamp warnings.



K

 

[Droverunner]

Yes doggedly sticking with the ntg2.5.

Which Command version do you have Kenny?

 

[KennyN]

Yes doggedly sticking with the ntg2.5.

Which Command version do you have Kenny?

It was the NTG 2.5 , i had it coded by Comandonline to switch to RVC when reverse was selected , they also updated the maps when they had the headunit. The camera was a "cheapo" from the far east.

IIRC the fact that the W219 was never available with a RVC from factory Comand had to load the software from an ML into the unit so the screen would switch to rearview when selected.

I also fitted a RVC to my Forester and just fitted a small button to supply 12V to the headunit to select the RVC screen.

K

 

[Droverunner]

Did you send it to them... if you don't mind what was the approx cost for the coding?

 

[KennyN]

Did you send it to them... if you don't mind what was the approx cost for the coding?

I did send it to them as they were too far away to just pop in.

It was around seven years ago so I would imagine prices have changed somewhat.

K

 

[Droverunner]

OK understood... I'll email them and ask.