Guest Posted December 24, 2012 Share Posted December 24, 2012 As I am sure of most of you have seen I have recently fitted an LED work lamp to the rear of my truck, I went out last night to test and photograph the front light bar, in the dark and rain realised how bad my normal reverse light is as clearly it spoilt my night vision. I have therefore changed my mind and want to link the reverse light to the LED light however I want the ability to switch it off when not required like when reversing the trailer, I also need to retain the ability to use it as a work light. The light takes its power from the auxiliary battery, so I assume I can use the relay live from the same battery and the switch from the reverse light circuit? Something in the back of my head is telling me the reverse light on a TD5 is a negative switched circuit but I will find the correct signal wire so that's no issue. So can you guys just sanity check this for me please? Cheers, Jason. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted December 24, 2012 Share Posted December 24, 2012 If you move the switch from the coil side of the relay to the switched side you could then wire it up using a single on-off-on switch, although thinking about it you could wire it up as is using a double pole on-off-on switch. Quote Link to comment Share on other sites More sharing options...
Guest Posted December 24, 2012 Share Posted December 24, 2012 Cheers Barry, The light is installed with the switch at the rear so that I can turn it on/off from the back door when cooking etc. The idea behind putting the second switch on the relay was that I could turn the reverse function on/off from the drivers seat. Jason Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted December 24, 2012 Share Posted December 24, 2012 Ah ok, hadn't realised that, thought you were going to end up with two dash switches. In which case ignore my suggestion Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted December 24, 2012 Share Posted December 24, 2012 BTW if you move the fuse to the common path near the battery positive terminal you will only need one, is there a reason for two that is not apparent in the diagram? Quote Link to comment Share on other sites More sharing options...
Simon Smith Posted December 24, 2012 Share Posted December 24, 2012 You need to move the coil feed for the relay to the other side of the reverse light switch too. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 24, 2012 Share Posted December 24, 2012 reverse lamp will be neg switched, i.e ground one side to illuminate. also your relay coil needs to be wired parallel across reverse bulb (no separate feed). You have it in series with the bulb at the mo. 2x 12v =24v. I'll try and do pictures if time later. Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted December 24, 2012 Share Posted December 24, 2012 How about something like the attached? Except that SW1 and SW2 is a single on-off-on switch (couldn't find one in CircuitLab). One switch to rule them all. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted December 24, 2012 Share Posted December 24, 2012 Can't believe I missed that one, it's obviously too early in the morning for me. As Simon and Pete have said, the gearbox reverse light switch is not in the circuit with the relay coil. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 24, 2012 Share Posted December 24, 2012 have a look at this circuit, two options for switches etc Quote Link to comment Share on other sites More sharing options...
potato head Posted December 24, 2012 Share Posted December 24, 2012 Rightly or wrongly mine are setup a little differently. I need to make 3 seperate conditions before mine come on with the existing reverse light. Ignition on, reverse selected, sidelights on. I also have a dash mounted override switch that operates the lights when the ignition is off. Quote Link to comment Share on other sites More sharing options...
Guest Posted December 24, 2012 Share Posted December 24, 2012 Cheers Guys, Sorry I didn't explain myself very well or draw things very well.... I didn't mean to put the relay feed before the gearbox switch or make it look like the batteries were running in Series, Both my Aux batteries are wired in Parallel. The left hand side wiring is already sorted with the fuse etc for the work light and my switch is installed in the rear quarter-light trim and is operated from the rear door. This works well for the work light purpose and I want to retain the ability of switching from the rear with no ignition on as it takes this feed from Aux battery I don't need to worry about starting voltage. Clearly it would be fairly easy to just stick a relay in and take a feed from the reverse light but as I say above I want the ability to turn this off when that level of brightness is not required. However what I don't want to do is have to have 3 way switch on the dash as I know I will be forever having to go back and forth to the front to swap the switch over to the correct position, as every time the door is open we will loose heat from the sleeping area. I have made a fume curtain so the back door can be opened without loosing any heat from the bed area. I have had another go at drawing things. Jason. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted December 24, 2012 Share Posted December 24, 2012 Yes ign still needs to be on, my drawing was a bit vague with the main batt, fuses etc. Just the feed from the ign/fuse box as factory, the only addition is the relay coil across the reverse lamp. sidelights would stop you leaving the switch on and flattening aux batt, but would flatten it quicker with sidelights left on? unless you have led sidelights as well. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted December 24, 2012 Share Posted December 24, 2012 Shouldn't the wire to the relay coil that has your manual switch in go to the other side of the reverse lamp? Quote Link to comment Share on other sites More sharing options...
Simon Smith Posted December 24, 2012 Share Posted December 24, 2012 You moved the switched feed to the relay too far. Needs to be between the switch and the bulb. On your drawing you will have the same voltage either side of the coil. Quote Link to comment Share on other sites More sharing options...
Simon Smith Posted December 24, 2012 Share Posted December 24, 2012 Seems I took too long to type that Quote Link to comment Share on other sites More sharing options...
Guest Posted December 24, 2012 Share Posted December 24, 2012 OK Guys you spotted the deliberate mistake!! Well done! Shouldn't the wire to the relay coil that has your manual switch in go to the other side of the reverse lamp? You moved the switched feed to the relay too far. Needs to be between the switch and the bulb. On your drawing you will have the same voltage either side of the coil. OK guys you spotted the deliberate mistake well done... Jason. Quote Link to comment Share on other sites More sharing options...
Ben_J85JTY Posted December 24, 2012 Share Posted December 24, 2012 Jason, Are you going to be using the 7.5inch LED lights for this? I ended up getting 2 slightly smaller ones and wireed them in a similar way to your diagram above. The only difference was that because the draw was so small I could do away with the relay on the revering light and feed all the lights from the reverse circuit. The plus side is that when you use the switch the reverse light comes on as well for more light to cook by. The down side is that if you have left it in gear (reverse) the feed powers the ignition circuit and the fuel pump starts to whirr. The easiest place go get at the reverse wire is from the lamp itself then its easy to feed the return to the switch or relay. I can get some pictures of my install if it would help? Quote Link to comment Share on other sites More sharing options...
Guest Posted December 24, 2012 Share Posted December 24, 2012 Yes Ben, It's for my 7" LED light, I was thinking of taking the feed from my 12S connection in the battery box as there is a relay to supply the trailer reverse under there up to the switch from there and the feed I would run along the aux wiring circuit I have installed to the light above the switched live on the rear trim. Jason. Quote Link to comment Share on other sites More sharing options...
Ben_J85JTY Posted December 24, 2012 Share Posted December 24, 2012 Sounds fair. The Amp draw is so small that a carling switch is man enough to hadle the feed from the Aux without any problems. It seems an awful long way to wire from the exisiting relay when there is already a feed so close to the rear door, but I guess its a factory esq way of installing it all! Quote Link to comment Share on other sites More sharing options...
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