Reverse lights and on demand lighting wiring question

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2fpower

2fpower

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I bought a flush mount led light for my new bumper build and my goal is to be able to have it turn on when in reverse, and be able to turn it on with dash switch.

Any fancy way to wire up the reverse lights to be able to turn on with switch in addition to automatic reverse lights.

Not worried about power demand as all lights will be led now.

Can I just wire hot line to switch then to the same wire going back to taillights, or do I need to add some relay?
 
yes, I would fuse before the switch.
 
yes, I would fuse before the switch.
 
You can easily tap into the reverse lights power wire. That circuit is fused already. However, you will need a diode on the switch. When you override the reverse circuit with a switch it will send 12V into the ECU/Stalk and illuminate other things you don't want. Put a diode on the OEM wire, so it stops power from feeding back into the ECU.

How many AMP's to your LED lights use? You may be able to get away with no relay harness and utilize the OEM harness. Be careful, too much power draw can heat up the OEM stuff...and you'll have a bad day.
 
There's nothing else connected to that circuit, beyond the switch at the tranny. You can just run (fused) 12v from a switch to the circuit where it comes out of the switch at the tranny or thereabouts.

If the switch is on and the rig is on and in reverse you have two 12v paths that connect to each other. The only possible issue would be if the ignition-switched fuse the reverse lights normally run off blows, then the aux fuse would be feeding that entire circuit as long as you were in reverse. If you're worried about it, use a fuse for the aux circuit that is 5a lower than the main fuse.
 
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So working backward, if I connect power past the switch at the tranny ( if I splice in to the line headed back to the reverse lights) and tap in switched 12v power with 5 amp fuse, I should not have any issues?

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kelly, can ya do me a favor and get this all dialed in and just let me know how to wire it . and where you are finding those cool switch covers for the carling switches? My stuff is still on the slow boat from china and i'm wanting to do the EXACT same thing..
 
Sounds like a trade. I will get this figured out and help you wire it, and you can help me wire me 3FE. :)


Oh, and cruiserheads have the switches. I found them on ebay.
 
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IF anyone is reading this thread to learn something way beyond my level of fun. I started yesterday to figure out if I can use my two position rear fan switch from an 80 for this application. Answer is yes, but takes some thinking and swapping to make it run for + side switching.

https://forum.ih8mud.com/threads/rear-heater-switch-pin-out.148815/
 
Another wrinkle.

I am adding a front and rear camera system to the rig. When you put it in reverse, the camera switches to the rear camera. You splice in a wire to the rear lights and when it is hot it switches.

Will the above plan, it will switch to rear camera whenever I hit the rear lights.

So, trying to decide if this will not matter, if I can override at the monitor what camera I use, regardless of reverse power.

If I use the relay and the switch shown in the diagram above, this would fix this (if it is an issue).
 
The PO of mine had wired in a switch for the reverse light and I wanted to get rid of it because I was constantly leaving it on due to my attention span of a gnat... I ran new wires from the lead off the transmission and just plugged them into the ends from the switch. Now if I made that a 3 way connector I could keep it connected to the switch and turn it on when I wanted to. The power is coming from the fuse box so no need to add another inline fuse. You could even tap the camera into the switch.

I may be wrong on this, but it seems to be right. I've wired some strange stuff at work (commercial diver) and usually under a time constraint. I hope you get it worked out.
 
Your going to have to draw that out. My attention span must be shorter, as I don't see what that would look like.
 
I did something like this a long time ago. I started out using a few IRF450s, but later used relays. Not too difficult to implement, and this construction does not require the use of diodes. I have re drawn this and hopefully the image will post ok. Note that the IGN, PARK (parking lights, or running lights), and REV circuits all have a fuse somewhere else besides this schematic.

The intent here was that I wanted to have an option of having my auxiliary rear lights come on when it's dark outside and I use reverse... and the switch is in the position for this condition (in the image, it's DOWN). The other condition is to have them come on whenever the switch is UP (and the engine is running). The third switch position for the switch is in the middle, which is OFF. This STDT switch has 3 positions, where the middle position is disconnected. I think I got it from Radio Shack or local auto parts store, but it is a common configuration for a STDT switch.

If the wiring architecture is such that the REV signal is always tied to 12V, and the switch GROUNDS the line, then you can add 12V to the high side of the coil (where the PARK circuit is in the image), and add the REVERSE to the bottom side of the coil. Then just move the PARK to the other spot on the relay. The reason that the PARK circuit is where it is, is because lights are always allowed to turn on even if the ignition is off (this is an FMVSS requirement). In the image, there is no current draw on this circuit when the parking lights are on and the ignition is off.

IMAG1200.webp
 
Thanks for the image.

So, I ran out of time and I wired it such that I just tied the switch into the wire going to the rear lights.

Here is what I found out.

When I hit the new light switch, the reverse lights go on, and so will my new hot line for LED general lighting. perfect. On the dash, the 1 light stays on and so does R. Ok, no big deal.

Here is the weird one.... when in drive, tranny at 1 and T/C low, typically it will stay in lowest gear. If you give it gas, it stays in lowest gear.

When I hit the rear lights on, it will start shifting gears as I accelerate. Going downhill, this could be bad.

So, I will have to work on this again.


K
 
Wow that is strange. I believe this is how i wired mine. I have not had any problems so far.
photo (3).webp
 
Yep, that is the same as how I wired them up. Does your "R" light go on when you hit the lights?
 
No it does not. i think because the relay switch is open (meaning off)
 
Sparky_Mark said:
I did something like this a long time ago. I started out using a few IRF450s, but later used relays. Not too difficult to implement, and this construction does not require the use of diodes. I have re drawn this and hopefully the image will post ok. Note that the IGN, PARK (parking lights, or running lights), and REV circuits all have a fuse somewhere else besides this schematic.

The intent here was that I wanted to have an option of having my auxiliary rear lights come on when it's dark outside and I use reverse... and the switch is in the position for this condition (in the image, it's DOWN). The other condition is to have them come on whenever the switch is UP (and the engine is running). The third switch position for the switch is in the middle, which is OFF. This STDT switch has 3 positions, where the middle position is disconnected. I think I got it from Radio Shack or local auto parts store, but it is a common configuration for a STDT switch.

If the wiring architecture is such that the REV signal is always tied to 12V, and the switch GROUNDS the line, then you can add 12V to the high side of the coil (where the PARK circuit is in the image), and add the REVERSE to the bottom side of the coil. Then just move the PARK to the other spot on the relay. The reason that the PARK circuit is where it is, is because lights are always allowed to turn on even if the ignition is off (this is an FMVSS requirement). In the image, there is no current draw on this circuit when the parking lights are on and the ignition is off.
Click to expand...

I think that I finally understand this diagram now, but have a question. So you are using two relays in this diagram.

I wonder if it can be done with one.

I will post up a pic from my phone, but here is my verbalization. First add a SPDT switch. This will have a hot fused line (mine will be hot always, so I can turn the lights on regardless of key on) going to switch. At position 1 the power goes to relay 1. At position 2, power goes to reverse lights.

Relay 1 is basically a break for the stock circuit. So you take the existing reverse light wire going to the reverse lights, but after the transmission switch, and put a relay there. (note, position 2 wire connection will be inserted after this relay). When position 1 is at switch, the relay is closed connecting the existing wires for stock operation. When it is open (and position 2 is at swtich), it breaks this connection, so power cannot backfeed and do what I am experiencing.

I don't see what the need of the second relay, unless you have more power draw. With LED lights, I don't have that issue.

Picture in next post.

Thoughts?
 
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