I have a question for a GM tech. I own a 2007 GMC Sierra crew cab (new body style). I am wondering how much pre-wiring actually exists for various accessories from the factory?

For example, does the wiring already exist for a compass, if I were to get the rearview mirror with the compass, will it simply plug in and work?

Side mirrors with LED turn indicators...does the wiring already exist in the doors, or will new wiring have to be run?

One last...overhead DVD. Is the wiring already there above the headliner?

I know that this answer will most probably come from a GM tech, so thanks in advance!!

David Wright

i can tell you what i know about the mirrors- based on what i've seen and based on a GM bulletin #PIT4417B (document id#2008538). The RPO (regular production options) codes are 3 digits, usually found on a square/rectangular sticker inside the glove box. The available outside rearview mirror RPO's for the 2007 new body style truck are: Base level power DL8, Power folding DL3, and Camper DPN.

Because of the new electrical architecture used on these trucks, the mirror swap procedure is more involved than with previous models, according to the bulletin. You first need to determine if the switches on the doors are actually switches, or if they are door modules. This can be determined witht the scan tool- if it can communicate with the switch, it is considered a module. If the scan tool cannot communicate with it, then it is considered only a switch. The modules have logic in them that control other door functions, and are programmable to accept any of the 3 types of mirrors.

If the door has the switch, only the base power mirrors (DL8) and camper mirrors (DPN) can be used. If the vehicle has the base power mirrors and the camper mirrors are added, additional wiring will have to be added for the turn signal L.E.D's to work.

Sorry this is so long, but i also found something out along the same lines of your questions today from GM that i thought was interesting. A customer succesfully added a driver information center to his vehicle that didn't originally come with it at all. He skillfully patched it into the vehicle's electrical system and was able to achieve almost all of the original functionality of it. Only he couldn't get the personalization to work. After some extended research, a phone call went out to technical assistance. i know that GM frowns on this kind of thing, but i wasn't sure why.

The person i spoke to said that used car lots would buy cars with fewer options and go to wrecking yards, buy the parts and program the systems to work, and would mark the vehicle price way up because of the added options. Apparently that's why they're so tight about handing out calibrations. There's one more bulletin that addresses the add-on of OEM options; bulletin #PIT3981E (document id#1999509). All that says is if the vehicle didn't originally come with an option and GM doesn't sell a kit to install it, don't do it. They pretty much cut you off from warranty repairs and technical assistance for anything installed that they don't approve of.

Sounds pretty harsh, but i'm a believer that if it can be done, and works like it's supposed to, and the customer knows the potential risks (being cut off by GM) of installing it and is okay with that, then do it.

i have done some installs of factory DVD players on the new body style yukons. None of those come with pre-wiring for the DVD player. The install kit- which is made by GM, comes with a harness that is plug and play to connect the system to power. All it comes with is infrared headphones though. It doesn't play through the vehicle's sound system. Once the headliner is cut away, it does reveal pre-cut mounting holes for the DVD docking station to bolt onto. That makes the install pretty easy. i haven't researched into it too much, but it also appears that there are headrest DVD players available that look like they do patch through the audio system. The best thing to do there would be to see if your dealer/A dealer sells those accessories. If you can find a good parts department and a good electrical tech to work with you, there shouldn't be anything to worry about.

Thank you for this information! I appreciate the time and effort. I am most intersted in installing a replacement rearview mirror that would allow me to retain my ONSTAR and give me a compass/outside temperature feature. The temperature feature is what I'm really after. I think that these mirrors are also auto dimming. Anyway, I am really curious if this mirror will simply plug in and fully function. Again, right now, I have a simple manual dim, Onstar mirror.

I went to Circuit City yesterday and had an aftermarket overhead DVD installed for $500. GM wanted nearly $2000. While the GM version would have been a little more "handsome," I couldn't get past the extra $1500 entrance fee...

Again, thanks for all of the help!

Dave

i can tell you what i know about the mirrors- based on what i've seen and based on a GM bulletin #PIT4417B (document id#2008538). The RPO (regular production options) codes are 3 digits, usually found on a square/rectangular sticker inside the glove box. The available outside rearview mirror RPO's for the 2007 new body style truck are: Base level power DL8, Power folding DL3, and Camper DPN.

Because of the new electrical architecture used on these trucks, the mirror swap procedure is more involved than with previous models, according to the bulletin. You first need to determine if the switches on the doors are actually switches, or if they are door modules. This can be determined witht the scan tool- if it can communicate with the switch, it is considered a module. If the scan tool cannot communicate with it, then it is considered only a switch. The modules have logic in them that control other door functions, and are programmable to accept any of the 3 types of mirrors.

If the door has the switch, only the base power mirrors (DL8) and camper mirrors (DPN) can be used. If the vehicle has the base power mirrors and the camper mirrors are added, additional wiring will have to be added for the turn signal L.E.D's to work.

Sorry this is so long, but i also found something out along the same lines of your questions today from GM that i thought was interesting. A customer succesfully added a driver information center to his vehicle that didn't originally come with it at all. He skillfully patched it into the vehicle's electrical system and was able to achieve almost all of the original functionality of it. Only he couldn't get the personalization to work. After some extended research, a phone call went out to technical assistance. i know that GM frowns on this kind of thing, but i wasn't sure why.

The person i spoke to said that used car lots would buy cars with fewer options and go to wrecking yards, buy the parts and program the systems to work, and would mark the vehicle price way up because of the added options. Apparently that's why they're so tight about handing out calibrations. There's one more bulletin that addresses the add-on of OEM options; bulletin #PIT3981E (document id#1999509). All that says is if the vehicle didn't originally come with an option and GM doesn't sell a kit to install it, don't do it. They pretty much cut you off from warranty repairs and technical assistance for anything installed that they don't approve of.

Sounds pretty harsh, but i'm a believer that if it can be done, and works like it's supposed to, and the customer knows the potential risks (being cut off by GM) of installing it and is okay with that, then do it.

i have done some installs of factory DVD players on the new body style yukons. None of those come with pre-wiring for the DVD player. The install kit- which is made by GM, comes with a harness that is plug and play to connect the system to power. All it comes with is infrared headphones though. It doesn't play through the vehicle's sound system. Once the headliner is cut away, it does reveal pre-cut mounting holes for the DVD docking station to bolt onto. That makes the install pretty easy. i haven't researched into it too much, but it also appears that there are headrest DVD players available that look like they do patch through the audio system. The best thing to do there would be to see if your dealer/A dealer sells those accessories. If you can find a good parts department and a good electrical tech to work with you, there shouldn't be anything to worry about.

I just looked thru the accessories catalog and there is no mirror accessory kit so I am guessing it not a plug and play item you can add easily.

http://gmaccessoriesstore.com/sierra-1500-crew-inch-short-c-268_269_278_284.html?page=1&sort=2a