General 12v Vehicle Lighting Circuit Help

Thread Starter

anyone844

Joined Nov 19, 2022
1
I don't know if this is the right place to post this question, but with the amount of knowledgeable people in these forums, it's worth a shot.

I've been messing around with strobe modules for a bit. So far, I've been able to make a range of lighting components strobe for example led bars, led pods, low beams/high beams, and reverse lamps while still retaining their normal solid operations. The way I've been accomplishing this is by creating a 12v dual input circuit using some Rectifier diodes(Ex:IN4007/IN4508/10A10).

For a while now, I've been wanting to expand more into making other stock lighting components have the same strobe function. For example, reverse lights, parking lamps, cargo lamps, daytime running lights and license plate lamps, but would hate to have to run a wire for each component. My question is do all parking lamps share the same 12v circuit straight out of the bcm or fuse box or would my only option be running wires to each light harness/plug?? Would it be the same for other circuits??? Been thinking about using a power probe to test circuits but dont know whats the safest way to go by using the power probe without damagin bcm or any other component, dont know if I'm making any sense, but I just haven't messed with stock vehicle wiring circuits enough and wanted to get some advice before messing anything up.
 

MrSalts

Joined Apr 2, 2020
2,767
I don't know if this is the right place to post this question, but with the amount of knowledgeable people in these forums, it's worth a shot.

I've been messing around with strobe modules for a bit. So far, I've been able to make a range of lighting components strobe for example led bars, led pods, low beams/high beams, and reverse lamps while still retaining their normal solid operations. The way I've been accomplishing this is by creating a 12v dual input circuit using some Rectifier diodes(Ex:IN4007/IN4508/10A10).

For a while now, I've been wanting to expand more into making other stock lighting components have the same strobe function. For example, reverse lights, parking lamps, cargo lamps, daytime running lights and license plate lamps, but would hate to have to run a wire for each component. My question is do all parking lamps share the same 12v circuit straight out of the bcm or fuse box or would my only option be running wires to each light harness/plug?? Would it be the same for other circuits??? Been thinking about using a power probe to test circuits but dont know whats the safest way to go by using the power probe without damagin bcm or any other component, dont know if I'm making any sense, but I just haven't messed with stock vehicle wiring circuits enough and wanted to get some advice before messing anything up.
It really depends on the vehicle. Some vehicles use the CAN bus to activate and deactivate switches while others are hard wired into , for example, the brake switch at the brake pedal. The serial communication CAN bus is growing in popularity because paying once for a complicated software and a simple wiring harness is much cheaper than the complex wiring harnesses (loom) of a modern vehicle if each feature had its own complete circuit and switch mechanism.

Some systems also have their own current draw maximums or they throw an error code.

You'd be best off looking to see if your vehicle has a trailer pigtail available from the manufacturer. The last two vehicles I needed to add a trailer to, a Honda Odyssey and a Honda Pilot, each had a socket near the rear left tire - Honda sold a pigtail that plugs into that and you get access to all taillight, brake, turn signal and back-up lights. Check your vehicle's manual to see if a towing hitch package is available and if you can buy just the electrical pigtail without buying the hitch.
 

Tonyr1084

Joined Sep 24, 2015
7,787
Check your vehicle's manual
Also check your local Department of Transportation for regulations on modified exterior lighting. What you propose sounds like something that could get you in trouble with the law. If it's a "SHOW" car and not operated on the streets for anything other than shows then chances are you can get away with it.

I just put a ladder rack on my truck. Wanted to add high lights to improve visibility. State ordinances wouldn't allow me to make my own lamps. They had to be DOT approved. And yes, I asked before building. Prior to the rack I had a board with some DOT tail lights mounted on a steel beam for when I hauled lumber that stuck out more than 3 feet with clamps to hold it to the lumber. Two flashing yellow lights and two brake lights. They plugged into my trailer plug. Going to put that on the ladder rack since the lights are DOT approved. They frown on home-made lighting. You and I are capable of doing a job that would meet or exceed DOT regulations but if they let us do it then they have to let idiots do it too. And who knows what red-necked lighting would appear on vehicles. Christmas lights? Halloween lights? Flickering candles? You have no idea the depths of stupidity out there. So DOT regulates exterior lighting.

Here in my state people are putting HID lamps on their vehicles. Vehicles that are designed for bulbs with shields internal so as to not blind oncoming traffic. Those HID lamps don't always have shades and will cast a blinding beam attracting the attention of cops and highway patrol. People DO get "Fix-It" tickets and fines. I suppose if it could be proved that one of those vehicles were responsible for an accident then the owner could likely be held accountable for the damages and or injuries. Check before you build.
 

Mullins

Joined Dec 31, 2021
168
If you want to know if 2 or more lamp are sharing the same 12v remove the harness from bcm end other similar device then give 12v to one lamp. Now all the rest of the lamp with the same 12v will come on. But I give you one advice buy on internet one manual workshop for your car and you will save a lot of time.
 

gerty

Joined Aug 30, 2007
1,305
Looks like I do the same thing you're doing.. I'm a member of our county rescue squad and I've been "elected" to take care of the electronics radio, siren, lights... Since we are volunteer we have a very small budget, so I have to flash existing lights.. For red lights on the front I have used led tractor trailer tail/brake lights with a flasher module. As stated above check your local/state laws before doing this..
Our laws here state we cannot travel with emergency lights on unless we also have the siren on.. If our siren should die on us, we must turn off the lights and travel "non emergency".. Also as stated above vehicles differ with the wiring, some have a fuse for the left , headlight and a different fuse for the right side, with the commands coming from the body control module. So you can see it's easy to mess up..

Edit: just saw how old this post is, don't know why it showed up today ??
 
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