Does anyone know about this automotive electrickery?
I'm trying to wire a reversing camera into the car unfortunately powering it from the reversing lights makes this system think a bulb has failed and the picure becomes unuseable. Would placing a , say , 20 amp. relay in the reversing light circuit and taking the power from an unswitched supply avoid this problem? Taking power from there direct is not really an option as this is permanently live and the battery would drain.
My knowledge of car electrics is strictly cotton wrapped looms and milk bottle top fuse substitutes.
Not sure why putting the camera on the reversing light circuit would make the car think it has blown a bulb. Putting it through a relay might work but possibly giving it a seperate switched circuit might be better?
From my experience you need an interface which provides output depending on what information it receives via the CAN bus. i.e. it senses what the car is doing and supplies a 12V supply to your accessory when, for example, reverse is engaged.
Not sure why putting the camera on the reversing light circuit would make the car think it has blown a bulb.
Because you are changing the impedance of the circuit which the car electronics 'see' as a failed lamp.
Driving a relay would probably have the same outcome. Modern car wiring is a whole new ball game and apart from problems such as the one the OP is experiencing it is very easy to do serious (and expensive) damage if you don't know what you are doing.
I have a Swedish Range Rover, and find the "owners club forum" a very useful resource. You can guarentee you're not the first tohave a problem, or fit an accesory. Lots of helpful links to ebay parts that fix the problem (hint hint) or DIY parts that can be soldered in line.
Try putting a diode in the feed from the reversing lights, stripe to the camera. A 1N4142 should do. Should overcome the problem.
Surely this will reduce the current taken by the camera by an amount so small that the circuit will still detect a failure.
A relay might take sufficiently small a current to do the trick, though, a typical automotive relay takes a couple of watts, within the tolerance of the usual 2 x 21 watt reversing lamp bulbs. You could try putting a 2 watt instrument panel lamp in the circuit - if that doesn't give an error you should be all right to go ahead and spent the GBP 3-4 for a relay.
Elder daughter has a Seat "Sport". Oh, per-lease! A Seat "Sport" indeed.
Anyway, some mate of hers wired in a huge amp and speaker that take up most of the boot. Result for her = pleasing and very loud music from her ipod touch and mobile phone. No comment on the result for the rest of humanity.
Result for the car - all of the light bulbs fail on a regular basis. Bloody car electrics!!!
Or try taking a feed from both reverse lights to balance? It's not canbus which causes this, my Volvo bulb failure warning did this before canbus was invented by sensing the difference in voltage drop on each side.