Factory GM Navigation for 2003-2006 GM Pickups


This information is provided without any warranty whatsoever. USE IT AT YOUR OWN RISK. If you are not skilled in installing automotive electronics, DO NOT ATTEMPT THIS MODIFICATION YOURSELF. If you follow the guidelines listed on this site and your truck breaks, you get to keep both pieces.

WARNING: This page is under development and currently does not contain all the information you need to successfully do this modification. Your best bet is to read the following threads before you do this mod:

The above threads provide all the gory installation details, including wiring information. There's a lot of information to sift through in those threads. It will take some time read. Be patient. This write-up only discusses the BASICS, you will need to learn more to do this mod successfully.


Though GM does not offer a factory navigation system in the 2003-2006 full-size pickups, it is possible to retrofit a factory unit.

A factory navigation system installed in my 2004 GMC Sierra:

It is extremely critical that you obtain the correct navigation head unit. There are many units that will be identical in appearance but will not function in certain applications. The basic requirements are as follows:

Where can I purchase a Factory Navigation System?

  1. Your Friendly GM Dealer: Be prepared to bend over.
  2. EBay: Searching for "GM Navigation" typically turns up some good results. Be absolutely certain the seller is aware of EXACTLY what type of unit s/he is selling. All the navs pretty much look the same, but they won't all work in your specific truck. People have purchased dead units on ebay before, so make certain you're purchasing from a reputable seller! Most of these units will have been previously used, so you will need to have a GM dealer reprogram the "TheftLock" system to allow it to be used in your vehicle.
  3. Specmo: Visit www.specmo.com. Call the toll-free telephone number on their site to order one. These are new units. As far as I am aware, this is the cheapest place from which to buy a new unit.

Installation

See the above threads for wiring information for your particular navigation unit. I'd love to have time to do a full write-up on the installation and wiring, but it's just not in the cards. Installation essentialy consists of tearing your truck down to this point: Click for Photo in order to install the GPS antenna which must reside underneath the large upper dash panel. Then you run the VSS lead from the radio harness to the instrument cluster harness. Then just plug everything back in and go. (You absolutely MUST read the info in the above GM-Trucks/Avy Fan Club threads to get this right though).

Disassembling the Dash to Install Radio and GPS Antenna

You will need to remove the top dash panel, radio, and instrument cluster in order to run the install a nav unit, connect the VSS wire, and attach the GPS antenna. These steps explain how to tear your truck down to this point:

1. Disconnect the Battery:

It's under the hood. You can't miss it.

2. Remove the Dash Bezel:

Put key in ignition, turn to ACC or ON (no need to start), put gear selector in low gear. Adjust the tilt of the steering column to lowest position. Pull bezel away from dash. There are clips around the perimeter that are holding it in. This can be done very gently with minimal force. Once dash bezel is loose, it will still be difficult to remove due to steering column. To remove it, bring the top edge forward while leaving the bottom edge in place and "rotate" it out. You may have to push down on the top-rear part of it to get it out of the dash. This is somewhat tricky, but can be done without scratching anything. Make sure you don't scratch the bottom of the bezel on the hazard/flasher button.

3. Remove Climate Control Panel:

The radio is heavy and its wiring harness is short. If you leave the climate control panel unit in, you will likely scratch it when you try and remove the radio. I've seen a ton of trucks with this unit scratched due to removing radio without first removing the climate control. This unit is held in with two 7mm hex bolts and four plastic snaps. The unit has two connectors attached to the back of it that must be removed.

4. Remove Radio:

The radio is held in by three 7mm bolts. Pull them and remove the radio. There are one or two connectors on the back of the radio to remove.

5. Remove Instrument Cluster:

The instrument cluster is held in by four 7mm bolts. It has one connector that must be removed.

6. Remove Both Passenger Side A/C Vents:

Remove center vaned section of vent by carefully pulling on it and working it out. You can now reach in and pull the entire vent assemblies. You only need to remove the two vents on the passenger side.

7. Remove Passenger Grab Handle (over the air bag):

There are two release buttons that must be depressed in order to remove the passenger grab handle. There are white in color and somewhat difficult to find. They are accessed from inside the holes that until recently housed the passenger side A/C vents. When you push these two buttons, the grab handle can be pulled straight out.

8. Remove the A-Pillar Covers:

Pull these away from the A-Pillar at the top. You can then pull them up and out. You will need to disconnect the tweeters if you have a BOSE system. Be gentle with the tweeter connectors, they look fragile. Also be careful not to bend the A-Pillar Covers, as there will be a permanent curve in them if you do.

9. Remove Top Dash Panel:

First, remove the interior fuse panel cover from the drivers side, and the similar electrical cover from the passenger side. Behind each of these panels are two phillips head screws that must be removed to access the dash. Remove them.

Second, remove the array of 7mm hex bolts holding the top dash panel in place. There will also be two more phillips head screws to remove just to the right of vent adjacent the radio.

Third, remove the two 7mm hex bolts that were exposed by removing the passenger side A/C vents. One bolt is in each vent.

Once all these screws are removed, you can remove the dash bezel by pulling it toward you. There are six engagement points near the windshield.

Reassembling the Dash

Perform the above steps in reverse order.

A few warnings:

VSS Interrupt / Lawyer Override Switch

The GM Navigation system is programmed to disable many features when the vehicle is moving (at a speed greater than 5mph). The disabled features include entering destinations by POI name or Address, and even inputting a destination by memory point. This is moderately infuriating, especially in cases where a passenger is available to safely perform such tasks.

These GM navigation systems use a signal from the vehicle speed sensor (VSS) in combination with a directional gyro as their primary means of determing your position, speed, and direction. The GPS signal is used to repeatedly calibrate the position. The system only disables the aforementioned features when the VSS signal indicates a speed of greater than 5mph. Thus, it is possible to install a switch on the VSS wire to temporarily cut this information while the vehicle is in motion such that all capabilities of the navigation system may be used. When the switch is opened, the display will no longer reflect your travel, as the unit will temporarily believe that the vehicle is stopped. Once your destination has been entered, simply close the switch and the display will "jump forward" to your new position and begin routing you to your destination.

The unit is designed to work even if no VSS data is available. When no VSS data has been received for two minutes (but GPS updates indicate the vehicle is moving), the unit will begin using the GPS signal as its primary data source. The display will likely appear a bit more "jumpy" when in this mode of operation. The unit will NOT disable any features when operating in this mode. The only scenario where features are disabled is when it receives a speed greater than 5mph from the VSS.

A VSS cutout switch can be conveniently mounted in the four pod housing to the lower right of the nav as shown below. This switch was purchased from radio shack for about $3.

CD Players

The slot above the navigation screen will typically be occupied by the navigation map disc. You can remove the navigation map disc and play a CD in it, but in such a configuration all navigation features will be inoperable. Chances are you're not interested in spending more than $1500 for a CD player with a really big display, so an external CD changer will be necessary.

There are two GM CD changers that can be used in conjuction with the GM navigation head unit:

The first option is a unit made by USA-SPEC that is a convetional magazine-style CD changer that can be mounted under the rear seat (or wherever you have space for it). This unit comes with a very nice piggyback harness that will plug in between your XM receiver (if you have one) and your head unit.

The second option is to use an in-dash 6CD slot load changer sourced from a Denali or Escalade. This option requires splicing into the existing radio harness or making your own. The unit can be mounted in the lower cubby if you have the extented center console. This mounting location requires that you remove nearly the entire lower cubby from the center console. The cubby can be removed wit a sharp razor knife (score it several times first against a straight edge that is C-clamped to it, don't try to cut straight through). Additionally you will have to cut/dremel non-critical material from the back of the center console in order to allow the back of the changer to fit. The CD changer can be mounted to the front of the console via sheetmetal screws through some very hard plastic inside the console. The back of the unit is held up by a pre-existing shelf within the console. This procedure is NOT trivial/straightforward and if done incorrectly will result in some of those cheap-yet-somehow-incredibly-expensive interior parts needing to be replaced.

Completed Setup

And finally, here is the completed setup: