 | Home > In Car Electronics > Reverse Selected - Positive Feed? |
 
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558  
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Reverse light switch on gearbox is bit closer
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16th Jul 2015 6:33pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19579 
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There is certainly no easy acess unless you go to the rear.
Personally I would go to the rear anyway and make up a small loom to add in without cutting into the standard wiring. The parking wire if present often marked 'PRK SW' can normally be bypassed by simply putting to ground. The reverse as you mention is 12v, either tap into the reverse as you know or use a switch. Last edited by custom90 on 16th Jul 2015 7:25pm. Edited 1 time in total |
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16th Jul 2015 6:35pm |
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| Barney12 Member Since: 09 Jun 2015 Location: South West Posts: 744 
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Thanks guys.
Steve, your comment prompts another question..... I'm not sure I understand what the "parking" wire is for? I'm assuming its to prevent video/dvd playback unless parked? Sorry car electrics are not my forte! Barney |
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16th Jul 2015 7:16pm |
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| Go Beyond Member Since: 30 Jan 2012 Location: Headcorn, Kent Posts: 6676
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That's exactly what it's for
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16th Jul 2015 7:24pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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Yes park switch wire is so you cant play dvd while driving if its in view of driver which is illegal
connects to h/brake or park switch on a automatic as said it can be connected to earth and save running the wire to switch , but if you get caught or have a accident and they find a dvd playing your in the 5hit ( easy way is dont play a dvd while driving ! ) other option for reverse switched wire for camera would be to just fit a switch to just switch camera on when needed , also it can be used without reverse then to keep a eye on trailer etc while driving ( as far as i know thats legal , anyone know different? ) |
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16th Jul 2015 7:29pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19579
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As above that's true, although you may well find it actually effects functionality you want to use.
For example if you were towing a horsebox and you wanted a cam in the rear to keep an eye on what's going on back there the parking earth would prevent you. Putting a DVD on or other video would be illegal though whilst driving unless it was playing audio only. That is one issue covered, the next is the fact some vehicles handbrake wiring are live not earth as some HU's require. For this reason many ground this wire for this very reason. Mine is earthed, but frankly I rarely use any video anyway full stop. |
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16th Jul 2015 7:31pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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if you need to switch a earth feed to a positive or postive to earth it can be done easily with a relay
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16th Jul 2015 7:35pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19579
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As far as I'm aware it is, IWT sells a standalone horsebox monitor. Page 6 here: http://www.iwt.co.uk/iwt-parts/download/142 In response to munch yes, your right you could but why when you can simply ground it. Just creating work in my opinion. |
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16th Jul 2015 7:37pm |
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| Go Beyond Member Since: 30 Jan 2012 Location: Headcorn, Kent Posts: 6676
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The hand brake switch on a Defender switches an earth which is what most HU require.
It is easy to get to so no reason not to wire it correctly. Most HU require a positive to enable the rear view camera and the Defender gear box switch switches a negative so a non starter, unless you use a relay. We always pick up off the reversing light itself as we are running the reverse camera cable anyway but there must be a relay somewhere that controls the reversing light ??? |
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16th Jul 2015 7:39pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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I know horseboxes etc have cameras in rear etc , and guess its much the same as having a dash cam with screen
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16th Jul 2015 7:41pm |
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| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558
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no relay on reverse light , not heavy enough load i guess |
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16th Jul 2015 7:42pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19579
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The reverse is a dedicated load I suppose so directly live switched and fused.
Incandescent bulb would only draw circa 2.1A LED much much less. |
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16th Jul 2015 7:45pm |
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| Go Beyond Member Since: 30 Jan 2012 Location: Headcorn, Kent Posts: 6676
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But the gearbox switch switches a negative so how does that switch the reverse light ? |
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16th Jul 2015 7:49pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19579
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You can switch a live or earth, both work in the same way.
Either causes a break in the circuit, reverse selected switch engages and regular driving the circuit is broken. Usually the earth is switched anyway as it carries no load, unlike the live. Most items are earth switched via a relay due to the load such as aux spot lights or similar due to a fairly high load on the live. In the reverse it's a low load so it's directly switched no relay, so a very basic circuit indeed. It is however fused though and earth switched. |
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16th Jul 2015 7:55pm |
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