2011 gmc sierra

sparkydog · 06-16-2011, 02:47 PM

I set up this unit to be towed behind MH. I have Patriot brake system with tow bar. I installed extra bulbs in taillight assemblies, everything works fine. I realized that the truck brake lights do not work unless the key is on. I don't want to leave key in ign, but would like truck lights to activate when Patriot is engaged, as well as extra lights. My Jeep wrangler operates this way. Extra security to be seen! Any ideas short of leaving the key in ignition? It does not have steering wheel lock. Thanks in advance !

**Route 66** · 06-16-2011, 03:20 PM

Adding diodes would be the easiest.

sparkydog · 06-16-2011, 03:49 PM

route 66, as I understand I would still use the light wire that feeds the aux light, just tap into the taillight harness at the rear using diodes. I would assume that I need three diodes, left, right and tail lights? Or do I need four? Thanks

**Route 66** · 06-16-2011, 03:58 PM

I think 4 would be easiest. That's what I did in my Yukon and I tied the side marker light in also as it's a small bulb in the side of the tail light assy.

I used Roadmaster Hy-Power diodes as they have so little voltage drop, the original GMC bulbs appear to be at full brightness. I don't recall where I ordered them online from, and they are not cheap, but they are the best.

sparkydog · 06-16-2011, 04:12 PM

Thanks Route 66, It's nice to have confirmation on what I think I know! another project to be added to the list.

**Route 66** · 06-16-2011, 04:43 PM

As usual, there will be no charge for the assistance.

**Gary RVRoamer** · 06-16-2011, 05:59 PM

I'm unclear why the lights don't work unless the truck key is on. If you installed extra bulbs in the socket, they should be powered from the motorhomeand grounded thru a ground return to the motorhome. Using diodes is an alternate way to add lighting, but it doesn't change the fundamentals of how the power reaches the bulbs. I think you have something wired wrong.

**Route 66** · 06-16-2011, 06:08 PM

I understood the OP to want the OEM truck bulbs to light in addition to the aftermarket bulbs.

The problem with adding bulbs is that they are not in the optical center of the light assembly and therefore may not be very effective.

sparkydog · 06-16-2011, 06:45 PM

route 66 is correct. The extra lights I installed work fine, but as stated they are not in the optical center and are not quite as bright as I would like. On the truck the brake lights will not activate unless the key is on. Not sure why GM did that.