The HU'* for the 2K+ Bonneville are a high level output. By using the amp present signal, it'* my understanding the HU will adjust accordingly. This likely has a lot to do with the HU'* being more year oriented rather than whether the vehicle has an external amplifier or not. There are a variety of HU'* (AM/FM/Cassette, AM/FM/CD, AM/FM/CD/Cassette) but there is no further breakdown if they are going into a Bose or Monsoon equipped vehicle. Where another change occurred is when they replaced the AM/FM button with the BAND button. These newer radios (with the BAND button) have software capable of controlling the DRR (Digital Radio Receiver).

As for the TheftLock, these radios will not work in a vehicle unless there is a connection to a class 2 data bus. When the radio is first installed, it checks for this. It will read the VIN from one of the BCM'* on the bus and compare it with what is stored in memory. If the memory hasn't yet stored a VIN, it now retains a portion of that which was obtained over the bus. This radio is now set-up for the vehicle. Every time the radio is powered up, there is a query made for the VIN. As long as it matches what it currently has stored the radio will power up. If there is a mismatch, the radio will go into TheftLock mode and a Tech 2 is required to perform a VIN relearn. This allows it to learn a new VIN and exit TheftLock.

Yes. These are all class 2 devices and are controlled over the data bus. The HU will send a command to disable or enable audio out from these devices depending on user selection. This way they can share the same input on the radio.

Xenewise[/quote]

So do I understand this correctly...
1. If I have a head unit for my 2001 SE that does NOT have a separate amplifier, it is the SAME head unit as if it did.
2. If I want to add my own amplifier, all I need to do is have a connection to the "amp present" signal so the head unit will output the proper level. (if so, what is the pin out)
3. The head unit for a Bose system will work just fine with the Monsoon system.

Am I interpreting this correctly?

This is different than what I would expect (but there are a lot of things about this system that have been this way).

I'm just in the process of gathering information but yes, this is my understanding. In the 2001 MY, there are three part numbers GM lists for the Bonneville. One is for AM/FM/Cassette, one is for AM/FM/CD and one is for AM/FM/CD/Cassette. There is no further breakdown by Bose versus Non-Bose. The further evidence to support this is that I installed the AM/FM/CD/Cassette option into my 2002 SE and it worked flawlessly. Of course my SE did not have the external amp.

More information to follow later today...

Okay, here'* what I've found... The following part numbers are the most current as of the date this post was made:

25736703 - AM/FM/CD (RPO U1P) and is for 2000-01

25731290 - AM/FM/Cassette (RPO U1N) and is for 2000-01

25753860 - AM/FM/CD/Cassette (RPO U1Q) and is for 2000-03

25753859 - AM/FM/CD (RPO U1P) and is for 2004-05 (Black Buttons)

25753860 - AM/FM/CD/Cassette (RPO U1Q) and is for 2004-05 (Black Buttons)

I know there are several (additional) part numbers but this is what I have to date. Many old numbers you may see change up to the more current ones listed above.

Basically, there were three options for 2000-01 and this dropped to two options for 2002-05 because the AM/FM/Cassette was eliminated. Some other variations will include the replacement of the AM/FM button with a BAND button once XM radio was available. Head units without the BAND button will NOT support the Digital Radio Receiver.

P/N 25753860 is listed by GM for 2000-03 vehicles and supports there being no difference in head units between Bose and Monsoon. I had suspected this from other information obtained in the past but is now confirmed. The only variation is the amplifier itself. Bose was offered in 2000-01 and in 2002 was replaced by Monsoon.

I'm still doing research and will update once I have more information. Hawkjet - I'll answer your question soon but before I do, I need to confirm a couple of points.

Ok, checking the wiring diagrams from the FSM'* for 2000 thru 2005 Bonnevilles, here is what I came up with for the wiring...

2000
Amp Sense - Pin B6 Input (Grounded) Option U80
Amp Switched Power - Pin A3 Output

2001
Amp Sense - Pin B6 Input (Grounded) Option U80
14V Ref - Pin A3 Output

2002 thru 2005
Amplifier Present Signal - Pin B6 Input (From Pin A1 on Amplifier) Option UZ8
14V Ref - Pin A3 Output
Radio On Signal - Pin A6 Output (To Pin A8 on Amplifier)

So, on 2000 and 2001 models, pin B6 is grounded to tell the radio there is an external amp.

On the 2002-2005 models, the wiring is the same for all 4 years and adds the Radio On Signal to the amplifier as well.

Xenawise

While your at it, you wouldn't happen to know the pin for the RAP module wire, would you? I finally got an external chime for my aftermarket radio, plan on adding it in sometime or another.

Actually, there is no RAP wire present at the radio. The radio knows the ignition is turned on or off or to ACC through the Dash Integration Module (DIM). The DIM sends signals over the class 2 data bus to the radio. So, the module you purchased should read the the data bus and provide its own ACC power line to power your aftermarket radio. If it does not provide this output on its own, its the wrong type of module for this application.

Xenawise

The class 2 data wires in the factory harness are typically Purple but sometimes other colours like Pink are used.
Sometimes there are 2 wires instead of 1 that are data, usually side by side or stacked in the harness.

You can test it with a DMM should show 2-3 volts with the key in the Run position.

Regards,
Dutch