08 suburban dome light and dvd player

I installed a Boss BV8.5 in a 08 Chevy Suburban.  After reading some posts here, I ended up not using the dome light power.  I went to the fuse panel for a +12volt feed to the DVD player.  My problem is that I can't get the dome lights in the DVD player to work.  They are opposite of what all the other dome lights are doing.  I called the company any they told me to get a reverse polarity relay switch.  I've looked on the internet for such a thing, but can't seem to find it.  My problem is that I'm about 2 hours from the closest A/V store as well.  Any suggestions on what to do?  Do I really need a Reverse Polarity switch?  The DVD Player says to connect to a +12 volt source, so I'm not sure what to do.  Should I use a different ground than the one at the dome light?Wyominguy

Thank you so much!  I will get that and let you know how it goes.Wyominguy

Some possible issues, my guess is the unit you have works the domelight on a negative feed and the truck you have has a positive domelight. If this is the issue the relay will work BUT if your domelights fad off when they go out the relay will make a chattering noise as it is comes on and off. Two ways to fix this, one(and they way i do it) is to run the relay wires to the back of the truck, insulate it with foam and tuck it behind a panel so you don't hear it chatter. The other choice is to connect all 5 door triggers to the unit using diodes, but this will stop any supervision from working....Mike M2

Tech Manager

CS Dealer Services

I know it is a little late but don't ever tie into a gm domelight for any reason. It will prevent the bcm from shutting off and will eventually lead to premature battery failure, there will be a parasitic battery draw caused by this. In this case you should tag the door triggers and use a relay to supply the power for the aftermarket domelight.Certified Security Specialist

Always check info with a digital multimeter.

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Ok, i just don't agree. It makes no difference whether you use the domelight wires to power the domelight in a DVD unit. The car knows no difference between the original lightbulb  and the one you install, they are bulbs. It certainly doesn't stop the BCM from falling asleep. The only unit i know of that is a problem is Rosen, they do keep a draw when you power the light but it isn't the car it's the DVD itself. We have installed(no exaggeration) thousands of overheads in new GM trucks, never had an issue....Mike M2

Tech Manager

CS Dealer Services

^ Agreed, we do alot of those vehicles for overheads and i always go the the grey/black + domelight wire.  Not once have i had a vehicel come back for batttery related issue.  I guess ive just been reeeeeealy lucky, lol.Advanced MECP

Use a small capacitor across the relay coils and a diode to prevent the cap from discharging into the vehicle. This will prevent the relay chatter on GM vehicles that use positive trigger dome lights that gradually dim out. The only video units that don't like the GM battery feed to the dome lights are Rosen and this is mentioned in the install manual. They require a dedicated battery feed.sparky