12vDC sled deck wiring

[Lgndeck]

Hello everyone

Im in the process of making a snowmobile deck for my truck (basically a platform to carry snowmobiles that fits in the truck bed). im getting around to wiring in the LED lights i want. (running lights on the side, headache rack spot lights, interior bed lights)

I plan on powering everything from a 7pin trailer connector so its easily removable. I have most of it figured out but I have one thing I’d like some advice on -

I want the LED lights on the headache rack for loading/unloading in the dark. I would like these to come on with the dome lights (there are dome lights in the truck bed that i can splice into as i dont believe there is a pin for dome lights on the 7pin trailer connector?) that way when i unlock the truck the lights will come on.

I would also like them to be come on with a switch that will be activated when the tailgate is lowered. so if the tail gate is down and the dome lights time out the LED's on the headache rack will remain on. this means in some instances they would be getting power from both the dome light splice and the switch. do I need to add a diode on one or both of the wires feeding the power? will they just need one ground?

It’s a diesel truck so has two batteries that are run in parallel if that effects anything.

 

[Diver300]

If you want a light to come on from either or both of two feeds, you can often use two diodes.

Connect the anode of a diode to each of the feeds. Connect the cathode together and to the +ve feed to the light. The negative of the light connects to ground.

However, that assumes a few things.
1) Either feed can provide enough power to run the light in addition to what it normally runs
2) Both feeds turn on and off by switching the +ve.
3) The extra voltage drop from the diodes won't cause a problem.

Obviously the diodes have to be rated to take the current that the light takes.

Without knowing the details of the circuits you can't be sure if it will work. If there are no lights that come on when the tail gate is lowered, it is unlikely that there is a feed that does what you want.

 

[Tony Stewart]

Hmm.. when the tailgate goes down you are blinded by the head-rack spot lights. I hate glare.

How about Tesla cybertruck lights at bumper level? with magnetic gate sensor switch to activate FET switch for lights with diode-OR activated by dome light voltage on a separate 10A fuse all inside cab.

Choose a switch rated for at least 2x LED current for cooler operation rather than 125'C

Mag switch. Choose 0V off using pull down R with normally open switch to 12V to turn on Power switch
or Pull up R to 12V with normally closed switch with magnets lined up and door latched up with sensor out to ground so input high for off state and output low. Then it runs on right away on swing down.

Here the sensor can be used as a low side switch using the power board as a high side V switch. Small LED is optional 2mA is OK for Power off state and will look like a security light. So if RED 2mA from 10V drop V/I = 5 kohm or 4.7 with 20 deg. high brightness 10,000 mcd.

 

[Tony Stewart]

This interactive simulation allows you to click the switches. (try not to move it, if so ^z to undo.) R values may need to change to 5mA drive.