reverse camera to jvc head unit

[dansri]

i have a jvc dvd head unit and a reverse cam that fits in the no plate light hole, its all fitted and connected to the reverse light and head unit i get the cam picture by manually selecting it on the screen but not automatically when putting the car in revrse. my head unit has an extra wire on "reverse camera signal" (this hasnt been on previous head units ive had cameras on) does any one have any ideas where i should connect this or how to get it to show the cam automatically when selecting reverse? i tried connecting it to the reverse light where i connected the cameras power cable.

[Z80]

You should do the exact opposite : as all other switch sensors on the car, they are considered active when grounded (this avoids having to run live wires everywhere in the car).

The reverse switch is actually fitted to the gearbox, and as I said, grounded when closed.

However, your idea to use the reverse lights voltage is actually very good, and VERY easy to achieve.

All you need is a commutation NPN transistor and a resistor, so you can ground your car stereo's wire when the reverse lights are on.

No simpler circuit than that actually exists... You can even solder the components directly to each other and wrap them into insulation tape if you're in a hurry.

Use for instance a 2N2222 transistor. Connect the collector to your wire, the emitter to a ground point on the car (there's one by the rear left tail light, ground wires are bolted there), and connect the transistor base to the reverse light positive wire through a 10 K ohms resistor (or you can use any value you've got handy, up to 22 k ohms). The resistor HAS to be used, or the base current will be too high and will burn the transistor.

You can also use a relay. It will then be even simpler, though far bulkier, of course...

Use an automotive relay ; connect both pins marked "85" and "87" to the ground, the pin marked "86" to the reverse light positive wire and the pin marked "30" to your car stereo's wire. Job done.

If you really need schematics, just ask. ^^

[marc vectra sri]

got same problem I have a pioneer one tried connecting it to reverse wire on light and on the reverse wire on the headunit and kept getting blank screen so I've just pit mine to my amp and just select it manually

[davedrinks]

My pioneer avh-3200bt has a dedicated input for the reversing camera - mine was £20 delivered from china via the bay

The power for the camera is wired direct to the reversing lights and the head unit automatically switches to the camera when I put it in reverse

Cant remember if there any other cables but iirc I don't think there are

[marc vectra sri]

hi Mayer mine is the 3300bt same unit which wires did u put on the headunit

[ScotsDragon]

My pioneer avh-3200bt has a dedicated input for the reversing camera - mine was £20 delivered from china via the bay

The power for the camera is wired direct to the reversing lights and the head unit automatically switches to the camera when I put it in reverse

Cant remember if there any other cables but iirc I don't think there are

Same as mine, I select reverse and the reverse circuit powers my camera and 12v to stereo to activate.

[davedrinks]

hi Mayer mine is the 3300bt same unit which wires did u put on the headunit

Im sure the only cable connected to the HU is the video cable from the can but I could be wrong!

[marc vectra sri]

but wouldn't ya have to connect a wire to the reverse wire on the hheadunit for it to come on when ya select reverse I've got mime power to the amp on sub and it don't come on when I turn ignition on