Bed lighting vs cargo lamp

whitetrash21

put on da damn helmet day
Apr 29, 2008
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Trying to wire in bed lighting in my 06. Power and ground run up under hood. Power leg run to a relay, ground to frame. Pulled power for relay from the fuse box. Here's the fun part...... Went to run my switch trigger from the cargo lamp switch and it works on a ground. Power to the cargo lamp switch is constantly on but when the switch is pushed, the power on that line goes dead.

Anyone have an idea how I can tie this wiring into the cargo lamp circuit without pulling all the wire back and tearing the truck apart to find the constant to the cargo lamp itself??

I want the lights all on the cargo lamp switch ....that, and the bcm has a timer so if I forget they're on, it'll shut off after a delay.
 

Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
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Ok so your saying the light stays hot until the factory switch becomes grounded? So if power flows to the light and then to the switching device isnt it the same? Just use your run from the bat pos to the light strand (fuse before lights) from the lights to your relay. Run a hot control to your relay to switch it and on the neg side of the relay use your switch to complete the grounding.... your over thinking it man. Just take a break grab a cold one and think about it, and you will think to yourself duh!!!! Gulp gulp
 

bmc1025

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Jan 25, 2013
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Run the power from your fuse to terminals 86 and 30, trigger the relay with the switched ground to terminal 85, hook tour new bed lights to terminal 87.

I do not know if the BCM will turn off the ground to the cargo switch. If it does not, you will need to wire terminal 86 to a fuse or accessory that does while keeping terminal 30 wired to your fused power source.
 

whitetrash21

put on da damn helmet day
Apr 29, 2008
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As it sits right now, I have the lights hooked to 87, 85 is grounded to the frame, 30 is my power from the fuse, and 86 is my trigger wire coming from the cargo lamp switch inside.

However, the cargo lamp switch is powered all the time until it's turned on....then that line loses power. If I tap into it, the new bed lighting works when the switch is off and when I turn the cargo lamp on, my bed lighting shuts off.

I probably am.overthinking it but I grabbed the cold one(s) before I started this which probably isn't helping :D
 

whitetrash21

put on da damn helmet day
Apr 29, 2008
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Run the power from your fuse to terminals 86 and 30, trigger the relay with the switched ground to terminal 85, hook tour new bed lights to terminal 87.

I do not know if the BCM will turn off the ground to the cargo switch. If it does not, you will need to wire terminal 86 to a fuse or accessory that does while keeping terminal 30 wired to your fused power source.

Everything I could find (which wasn't much) says the relay control for the cargo lamp is in the bcm.... It's also on a timer....something like 10 or 15 mins.

I guess the one thing I can't figure is if the relay needs power to kick on the new lights, but my tap point on the cargo lamp switch loses power when it's turned on, how do I power the relay on with that switch??

Again, probably over thinking this but really don't want to have to.pull all this back and try to find the constant running to the lamp. I'm already this far in the dash, it'd be nice to do it from here
 

jlawles2

Well-known member
Jan 28, 2010
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If 86 is your ground, connect it to the switch.
30 and 85 come from the battery (fused).
Then 87 should get power when 86 goes from hot to ground and activates the relay.
 

bmc1025

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Jan 25, 2013
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The polarity on terminals 85 and 86 doesn't matter one has to have ground and the other has to have +12v. This activates the coil and flips the internal switch. The wire on the cargo switch that reads positive when off and ground when on will supply the ground to the relay to activate the coil.
 

Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
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41e8570c9747e16caf31e77ad9749dc1.jpg
try this i think this is what your looking for.... cheers


Sent from my iPhone using Tapatalk
 

bmc1025

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Jan 25, 2013
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Big Bone, KY
The above diagram is incorrect it will not function. OP just wire one side of the coil to the blue/white stripe wire on the cargo light switch and the other to a fused +12v wire.
 

2004LB7

Well-known member
Dec 15, 2010
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i haven't looked at the wiring schematics for that year lately but this is my recollection of how it should be wired
 

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Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
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The way i have it drawn is the same way yours is. The only difference is where you have power coming from and going to.... (you just skinned a skinned cat!) im just poking fun man.

BMC1025, why wouldnt it work? Arent you suggesting the same thing? You are telling him to use the blue/white wire from the switch. Isnt that what is drawn to control the led relay? You cant connect to the back side of the switch or the lights will be on full time. So im not sure how im wrong.


CHEERS to both.
 

2004LB7

Well-known member
Dec 15, 2010
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yeah, i didn't quite understand your drawing. they way it is done looks like if the button isn't pressed, ie: natural state, it will sort out the 12+ to the 12- and blow the first fuse.

i may just be misinterpreting the drawing though
 

Budneeds2beers

Aka Mike Honcho....
Aug 25, 2016
497
4
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Well i did draw the button wrong. It leaves the relay hot until the button changes state so it can use the switch ground to complete the circuit. But it wouldnt short cause it has only one path to ground. It cant backfeed the hot. But yeah your digram is better and easy to fallow if your not good with schematics.
 

whitetrash21

put on da damn helmet day
Apr 29, 2008
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The polarity on terminals 85 and 86 doesn't matter one has to have ground and the other has to have +12v. This activates the coil and flips the internal switch. The wire on the cargo switch that reads positive when off and ground when on will supply the ground to the relay to activate the coil.

I absolutely suck with drawings. Using what you said, I shouldn't have 85 grounded to the frame then?? It should be tied to the hot fused lead (30)....and my switch leg off the cargo lamp switch will be hot hot to the other side of the relay (86), thus interrupting the circuit. Once the switch is pressed, it will go to ground and turn on all lights??

That part confused me because you'd have power to both 85 and 86 all the time .... Thats no bueno??
 

bmc1025

Member
Jan 25, 2013
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Ill attempt to wire this up tomorrow with a relay. Before my last post I was in a parking lot waiting for someone so I used some pieces of wire and jumped the blue wire to the ground on my led strobe bar and aplied +12 to the other and it operated without pulling the BCM low enough to turn on the cargo light. The bar has over 50 leds and a microcontroller for the patterns.
 

RHallenbeck

New member
Aug 21, 2014
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Use a 5 pin Relay. Center pin is 85A wich has continuity when relay is not activated. USe the 12V cargo + source to activate relay then when you press the Cargo light you lose the 12V and the relay will turn off which will initiate continuity through pin 85A.
 

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bmc1025

Member
Jan 25, 2013
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Big Bone, KY
That would work also. I'm not convinced it is a NC switch though. I think it applies ground to the bcm when pressed. I will find out for sure tomorrow.