I'm installing lights in my truck bed, which is covered with a fiberglass lid/tonneau. I chose some LED tubes which are normally used for under car installation, they'll be mounted up under the bed lip.


I want the lights to be activated by the switch on the dash that currently controls the bed light found integrated with the 3rd brake light. I'm not sure if I can get the wire up into the 3rd brakelight/Bedlight. Is this the only way I can do it, or can the new LED lights be wired right to the switch on the dash? I'm guessing the switch on the dash is a relay, which would make me think that won't work.


Perhaps it's easier to get under the headliner to the 3rd brake light than I think. Any thoughts, suggestions, etc., would be appreciated.

if you do figure it out, let me know! i am trying to hook backup lights to the same switch (am gonna do the same in-bed LED thing after i get the line-x sprayed) and am having a helluva time doing it! the problem is the way the cargo light is wired. when the switch is OFF, there is power going to the light (at least from the switch) and when the switch is ON, there is no power. see the post "want better backup lights?" a few threads down for more of what im talking about.

I saw that thread a few days ago when I started searching here, it was a bit confusing. I'm half tempted to simply send power to the lights from somewhere on the fuseblock and just install another switch on the dash, or in the bed as someone else has already done, but with a switch that illuminates. I'd prefer it in the cab so I know when it's on, and so the OEM system would shut it down if I accidently left it on.


Automotive electrical systems are more complex than in days gone by. I don't want to take a chance goofing up an existing circuit/relay like the bed light and/or switch installed by the factory.

Tap into the bed light and use that to drive a relay coil. The relay contacts should supply the power to the lights from the battery. You just have to run the wire under the headliner, down the A pillar and through the firewall to get it to the underhood fuse box area. You can mount your relay there and run the single wire back under the truck to the bed.


Does that make sense?http://www.dieselplace.com/forum/smileys/smiley23.gif


On Edit: The relay coil requirements are very small and should not overload the extisting circuit that you are tapping in to. You might be able to grab a signal from behind the switch as well, but getting the power wire to the bed light would be easier IMO.Edited by: chuntag95

keith - i had the same ideas of just installing another switch. im gonna do mine on friday or sat morning and one way or the other, ill get em wired. ill post up with what i figure out.


chuntag95 - youre right, that would work with a NORMALLY wired circuit, but like i explained, its a funky wiring system. gotta love those design engineers http://www.dieselplace.com/forum/smileys/smiley5.gif

some relays have a normaly open and a normaly closed circut so you can have the relay turn the power off insted of on.

Will be installing by Saturday on this end as well. Basically I purchased a ground effects LED kit with 4 long tubes, will use 3 of them in the bed under the rails, and the last one under the hood. Should be a fun filled weekend. http://www.dieselplace.com/forum/smileys/smiley4.gif


I follow the thinking of using another relay at the button or at the cargo light, and then drawing power from the battery, will have to take a look under dash & cargo light to figure best way to install.


Painlesswiring.com has a simple explanation of how to use relays, I always have to go there to brush up on the idea. The other thread you participated in (backup lights) also had some very good links as well provided by others.


Think I've got it now, just need to start the project.

You can look at 12Volt.com for more basic info on wiring as well. For the light to work, there has to be a hot side and a ground for the light to have a voltage across it. If they have reversed the polarity, as gearhead said, use the NC out.

power the relay coil with ign. power, this way lights will not be on with key off. At the under dash relay center you should find one. Some relays have a small wiring diagram printed on the outer shell. I believe the coil is powered by #'s 85 and 86, 12v and accessory use #'s 30 and 87(could be wrong, check relay to be sure)

What color lights are you all using? Clear or colored for effect as well?

and where are you getting these lights. I have not seen strip led's lights

this is what i plan on using. marine grade so it will be safe outside the truck and perfect length for a 6.5' bed.


Cabela's Marine Rope Lighting (http://www.cabelas.com/cabelas/en/templates/product/vertical-item.jhtml?id=0022913016310a&navAction=jump&navCou nt=1&indexId=cat600053&podId=0022913&catalogCode=I E&parentId=cat600053&parentType=index&rid=&cmCat=M ainCatcat21276&hasJS=true)


depending on how much you want to spend, you can get neon or LED lights designed for under rice burners at pretty much any auto parts store or stylinconcepts.com. i like the rope lights cause they are easy, plenty bright, cheap and hold up well. i know several people who have put them under the gunnels of their flats boats and they light up the floor quite nicely so it should be perfect for the truck bed.Edited by: haneym

hayneym:


How do you plan to attach the lights?

Wire Clips (http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=278-1641)


home depot has black plastic ones that come in packages of like 25 but theyre basically the same thing.

I purchased white because I just wanted bright light in the bed when the lid is up or down at night. These are what I purchased, they come with clips to install.


LED Light Tubes - Ground effects package (http://www.superbrightleds.com/cgi-bin/store/commerce.cgi?product=ACCENTS)Edited by: Keith

The head lite/ driving lite relays on our trucks are switching the ground wire, so the relays have power and by grounding them turns them on.


May be why u have power off and when u check it turned on it doesn't have power because of the better ground than a check lite.


I can't remember if there is a fuse for cargo light or relay under the hood, if the fuse is switched for the cargo lite it could power another relay to do your lites.


There are some guys on here w/ the wiring diagrams and the can tell u which wire in the wiring block to tap for a relay or to power the lights.

I can't remember if there is a fuse for cargo light or relay under the hood, if the fuse is switched for the cargo lite it could power another relay to do your lites.


There are some guys on here w/ the wiring diagrams and the can tell u which wire in the wiring block to tap for a relay or to power the lights.


That would be the ideal, and the simplest right? There are some links to wiring diagrams, I'll have a look around again here on the site. I recall similar questions about relays and power when I installed a backup camera system. Thanks for the reminder.Edited by: Keith

Follow up post: Between Dmax Tim's 12volt reference and Terry from another thread, I'm almost done. Project on hold for a few days, didn't finish yesterday. The LED tubes provide enough light for me, however they're not as bright as normal incandescents would have provided.


Here are 2 excellent references to using a relay and reversing desired polarity as Dmax Tim mentioned and haneym pointed out.
http://www.the12volt.com/relays/page1.asp
http://www.the12volt.com/relays/relays.asp
<DIV = align=left>Here's another Dieselplace member's (Terry) write up which was extremely helpful. I'm not tapping into the reverse light, just the cargo light switch via C3 block under the dash.</DIV>
<DIV = align=left>http://207.53.239.181/~terry/truck/Backup-lights/</DIV>
<DIV = align=left> </DIV>
<DIV = align=left>Note, it appears my 2004 pinouts are different than what's shown on Terry's schematic, however color of wires is similar. Use a meter to find the right combo of pinouts. </DIV>
<DIV = align=left> </DIV>
<DIV = align=left>Another great resource for looking at electrical schematics and info</DIV>
<DIV = align=left> http://www.gmupfitter.com/publicat/2004_BB/2003_Beyond_LD_El (http://www.gmupfitter.com/publicat/2004_BB/2003_Beyond_LD_Electric_CK.pdf) ectric_CK.pdf</DIV>
<DIV = align=left> </DIV>
<DIV = align=left>Thanks to the guys who contributed, love this place.</DIV>
<DIV = align=left> </DIV>

keith, that first link to the 12volt site about coverting polarity is interesting, i hadnt seen that. i had read the 2nd link after finding it on a web search last week and determined thats what i needed (a normally closed single pole double throw relay) but radio shack didnt have em. i went down to discount auto and through trial and error, we determined the fog lamp relay out of a camaro is the correct type of relay. so i bought one but due to other stuff going on (including new ranchos arriving and needing to be installed http://www.dieselplace.com/forum/smileys/smiley2.gif), didnt get a chance to test the relay or install them. which way did you end up wiring yours - with a normally closed relay or normal relay wired like that link (both power and ground connected to power)?


this is the kind of cool stuff that you learn about how things work when you do the work yourself and have helpful knowledge bases like this forum! thanks guys!!Edited by: haneym

I'm installing lights in my truck bed, which is covered with a fiberglass lid/tonneau. I chose some LED tubes which are normally used for under car installation, they'll be mounted up under the bed lip.


I want the lights to be activated by the switch on the dash that currently controls the bed light found integrated with the 3rd brake light. I'm not sure if I can get the wire up into the 3rd brakelight/Bedlight. Is this the only way I can do it, or can the new LED lights be wired right to the switch on the dash? I'm guessing the switch on the dash is a relay, which would make me think that won't work.


Perhaps it's easier to get under the headliner to the 3rd brake light than I think. Any thoughts, suggestions, etc., would be appreciated. Guys,





I just ordered an LED Tailgate Bar from Ebay. Its by a new company called RECON. Its great. It mounts right underneath the tailgate and has left turn signal, right turn, brake light, and running light. It plugs right into your factory 4 prong adapter. People are stopping me asking me "where did you get that". I found it on ebay.Simply search for LED Truck Tailgate Bar.Excellent product or you can call there 800 number which is 866 999 6255. Good Luck Edited by: Gonefishin

Normally closed is exactly what we need, but I'll be using a single pull single throw (SPST), because I'm only turning on the new cargo lights from the source. The LED tubes work fairly well, but not a bright as normal incandescents. Mounted them and used a jump pack just to see what they'd look like.


I am having probs finding the relay, as well. Radio Shack, and 3 auto parts places don't have it in stock, so I'll order one via internet this week from 12volt or link from their site. 12volt and dieselplace both are great resources for this sort of thing

keith, see my post on the backup lights thread. i finished mine yesterday. if you go to a parts store, get a fog lamp relay from a 97 camaro (im sure there are other applications, but thats the first one i ran across). easier than ordering online.

I'll check it out this week. I didn't get a chance to do any more work to it yet. I'll check your follow up post out in a minute.


I'm assuming the fog lamp relay for a 97 camaro is simply a Normally Closed circuit. So when I hit the cargo light (cutting power to the relay), it will trigger power to the lights?


Thanks a million for the follow up, it's great to read an entire thread through to its conclusion. Sometimes we forget to post the final comments and findings of all our work. :) I'll do the same when I finally get this project completed.