XM Radio Install

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Head unit	-	The main radio unit that sticks out of your dash and has the display and buttons you use to control your stereo system
Amp	-	aka Amplifier. Receives audio signal from the head unit, amplifies it and sends it to the speakers and sub woofer. On the Hummers with Monsoon the amp is installed in the center ceiling console
Sub	-	aka Sub Woofer. Provides low end bass. On the Hummers with Monsoon the sub is installed under the left rear passenger seat
Dog House	-	A term for the large center console in the Hummer that covers the engine and holds the glove box, cup holders, HVAC controls, etc

Starting Equipment

Hummer factory optional Monsoon system:

Monsoon head unit with integrated tape
Delco CD Changer in the dog house
Monsoon amp
Monsoon Sub
Monsoon speakers (6 of them)

Goals

Add XM Radio functionality with maximum audio quality
No additional screens or visible units to mount in the cab (keep the clutter down)
Use existing amp, speakers and sub since I'm happy with the current sound quality

Solution

Must replace head unit in order to get integrated XM. All other alternatives require a second display to be mounted in the cab and using an fm transmitter or tape adapter (which does not provide the audio quality I want)
New head unit: Sony CDX-M850MP CD/MP3 Receiver
New CD Changer: Sony CDX-757MX CD/MP3 Changer (required because the existing Delco CD Changer can not be used with the new Sony head unit)
XM Tuner: Sony XT-XM01 - Designed to be hidden away, will be installed under the dog house behind the glove box so it's not visible
XM Antenna: Term XM-3 Low Profile Magnetic Antenna - Must be mounted on a metal surface with at least 2 square feet of surface area. Supports both XM satellite signals and XM terrestrial repeater signals.
Wired Remote control for head unit: Sony RM-X4S - Fully controls head unit, will be mounted in convenient to use location for the driver. Head unit has no buttons on the front when the display is closed so the remote is almost necassary.
Wiring harness adapters:
- Metra 80-1858 GM Wiring Harness adapter (to connect to the existing wiring harness in the truck)
- Metra SY1680 Sony Wiring Harness adapter (to connect to the back of the new Sony head unit)
Dog house blank face plate: AM General Part #6009428 - mounts over the hole in the dog house where the Delco CD Changer is currently mounted

Potential Problems

Getting the new head unit to correctly interface with the existing proprietary Monsoon amp and speakers
Where to mount the new CD changer since it is too big to fit in the old CD changer's mounting location in the dog house

Resolutions

The wiring harness adapters ordered solve the problem of interfacing to the existing Monsoon amp and speakers. Just plug and play. See below for a description of the Monsoon system for more information.
Mount the new CD changer under the right front passenger seat using the supplied brackets. This will require removing the seat, drilling holes in the seat frame and mounting the CD changer to the underside of the top of the seat frame. Fits well, is securely mounted and is easily accessed by the passenger.

Monsoon system

The Monsoon system is actually pretty straight forward. The inputs on the Monsoon amp are speaker level. This means the Monsoon amp is expecting to receive audio inputs that are amplified and suitable for driving speakers. For comparison, most aftermarket amps require line-level inputs just like the RCA plug line-level inputs on your home stereo. The fact that the Monsoon amp needs speaker level inputs makes it extremely easy to install an aftermarket head unit. With the right wiring harness adapters the speaker level outputs on the new head unit are sent directly to the Monsoon amp on the correct wires. The Monsoon amp is expecting four speaker inputs (right-front, left-front, right-rear, left-rear). The Monsoon amp uses those inputs to produce the sub output so there is no need for a separate sub connection from the head unit.

It is important to note that the Monsoon amp does not have a separate remote turn on connection like most aftermarket amps. The Monsoon amp knows when to turn on based on the audio inputs. When it sees that the audio inputs to the Monsoon amp are receiving a signal from the head unit, the amp turns on and begins powering the speakers. Again, this simplifies adding an aftermarket head unit because no additional wiring is needed. The Monsoon amp is able to detect the signal from an aftermarket head unit and turn on properly.

If you wanted to keep the Monsoon head unit but replace the amp, you could either get an amp that accepts speaker level inputs or get a converter that converts speaker level to line level. Those converters are common and relatively inexpensive. To control the remote turn on for the aftermarket amp with the factory Monsoon head unit, I would recommend tapping into the power connection between the Monsoon head unit and the Delco CD Changer. The current draw from the amp to enable the remote turn on will be minor and shouldn't affect the CD changer operation.

While it may be possible to find a way to use the factory Delco CD Changer with an aftermarket head unit, I did not investigate this possibility. There may be special adapters to enable this but in my experience proper CD changer operation is generally achieved only by using a CD changer designed specifically for the head unit you are using. Therefor I would recommend replacing the CD changer at the same time as the head unit.

Steps

Remove the factory Monsoon head unit.
- Make sure there are no CD's in the cd changer or you will not be able to remove the cd's once the Monsoon head unit is disconnected.
- Insert two security removal tools into the two vertical slots on the Monsoon head unit*
- With removal tools in place, grab the head unit around the outside bezel or by inserting your fingers into the tape door and pull the head unit out of the slot
- The head unit will come out far enough to access the back side of it. Carefully pull the antenna connection out of the right rear of the unit, then squeeze the release tab on the small connector (for the CD changer) attached to the pigtail coming out of the center rear of the unit and disconnect it from the pigtail. Likewise, squeeze the release tab on the large connector on the left rear of the unit and pull it out.
- With all wires disconnected, the radio is fully removed and can be set aside (This would be a good point to skip to step 12 and temporarily connect the new head unit to make sure that it works as expected. If so, disconnect and proceed.)
- Bend the mounting tabs on the original head unit mounting cage away from the dog house and remove the mounting cage. If you don't need the cage anymore it might be easier to simply fold the cage, rotate it and slide it out.
- On the back of the old Monsoon head unit is a rubber boot covering a metal stud. This slides into a hole in the back of the dog house to support the rear of the radio. Unscrew the rubber boot from the bolt. With a box wrench or pliers unscrew the stud from the back of head unit. Set the stud and rubber boot aside for installation on the new head unit.
*If you do not have the right security removal tools, you can very easily make them. Find any thin and stiff material and cut it so that it is 3/4 of the width of the vertical slots on the front of the Monsoon head unit. Make sure you cut it to be at least 4 inches long. You will need to make two. Just insert them into the vertical slots. Once you feel resistance they only need to go in another 1/4 of an inch at most. Do not force anything, only a very small amount of force is required to release the security tabs.
Remove the factory Delco CD Changer.
- Unscrew the four screws that hold the cd changer trim plate to the dog house and remove the trim plate
- Unscrew the four screws that hold the cd changer in place and slide it out of the slot
- With the cd changer out far enough to access the back side of it you can disconnect the single attached cable
- With the cable disconnected, the cd changer is fully removed and can be set aside
Remove the factory cd changer cable.
- Gently pull the cd changer cable out of the cd changer slot in the dog house and set it aside
Remove the glove box
- Remove the cupholder tray from the dog house
- Open the glove box and remove the four screws securing it to the dog house
- Slide the glove box out and set it aside
Remove the driver's kick panel
- Remove the kick panel by the driver's feet to expose the steering column and the wiring under the dash.
Mount the new CD Changer
- Remove the four bolts holding the right front passenger seat to the floor of the truck and remove the seat
- Turn the seat upside down on a stable work surface
- Attach the mounting brackets to the cd changer and place the assembly within the exposed frame of the seat. Carefully locate the assembly in the desired final mounting location and then mark the holes you need to drill on the seat frame
- With the seat securely held drill the four holes
- Mount the CD changer in the seat frame using the new holes
- With the seat out of the truck, route the CD changer cables (RCA and Bus) underneath of the trim next to the seat location in the truck and up into the dog house to the planned installation location of the XM tuner (behind the glove box)
- Reinstall the seat in the truck, taking care not to pinch the newly installed cables
- Connect the CD changer to the cables
Mount the XM Antenna
- Place the XM antenna on a clean metal surface on the exterior of the vehicle. In my case, I placed it on top of the light bar which has a flat metal screen. It is possible to mount it under the hood since the hood is fiberglass, but it still needs a metal mounting surface with at least two square feet of surface area.
- If possible, secure the XM antenna so it will not get knocked off by brush and trees. I used zip-ties for mine.
- Route the attached cable into the vehicle. I ran my cable along the light bar support bracket to the hood cut-out by the CTIS pump. I then cut away the rubber seal next to the CTIS pump where the hood release cable goes into the passenger compartment and pushed the antenna wires through there. I then resealed the hole with RTV sealant.
- Run the antenna cable behind the dash and dog house to the planned installation point for the XM tuner (behind the glove box)
Provide Power for the XM Tuner
- Wire the supplied power connector for the XM tuner into a switched and fused power source. I tapped into the switched power being supplied to the head unit through the new Metra wiring adapter since it is easy to work on out of the truck. This will turn on the XM tuner anytime the vehicle is on.
- This would be a good point to verify that the XM tuner powers up. Skip to step 11 and temporarily connect the XM tuner to the power wire. Turn the ignition to "ACC" or "On" and verify that the XM tuner powers up. If so, disconnect and continue.
Route the audio and control cables for the XM Tuner
- Run the RCA and Bus cables for the XM tuner from the empty head unit slot to the planned XM tuner location (behind the glove box)
Install the wired remote control
- Run the wire for the wired remote control from the empty head unit slot to the planned installation location (dash, steering column or trim panel next to driver)
- Securely mount the remote
Install the XM Tuner
- Connect the wires for the XM tuner: power, RCA, Bus, Antenna
- Using double backed super-lock velcro mount the XM Tuner to a flat surface behind the glove box (preferably onto the back of the truck's computer or next to it)
Install the new head unit
- Take the stud you had removed from the original Monsoon head unit and screw it into the back of the new head unit. The new head unit should have a threaded hole for this purpose. After the stud is installed, screw the rubber boot over top of the stud.
- Install the new mounting cage for the new head unit by sliding it into the head unit slot on the dog house and bending the mounting tabs on all sides to securely hold the cage in place
- Plug the Metra GM wiring harness adapter into the old plug hanging out of the head unit slot that was previously connected to the original Monsoon head unit.
- Plug the Metra Sony wiring harness adapter into the back of the new Sony head unit
- Connect the two Metra wiring harness adapters to each other
- Plug the FM radio antenna connector into the back of the new head unit
- Slide the new head unit into the mounting cage until it securely locks in place
- Snap the supplied trim piece into place around the new head unit
- Fully test your system before proceeding. Check the following items:
  - Speaker balance and fade
  - Radio display dims when the parking lights are turned on
  - CD changer is recognized and operates properly
  - Xm Tuner is recognized and operates properly
  - Wired remote functions properly
Clean up
- Go back and neatly wrap and secure any loose wires both inside the dog house and out. Make sure nothing will get pinched and there are no wires hanging loose.
- Install the new cover plate for the dog house where the old cd changer used to be
- Install the glove box and cup holder tray
- Replace the driver's kick panel