PAC AAI-GM24 Auxilary Input Problem - Need help!

[Zing]

Yes, there are 4 loose: red, black, yellow and orange. Do you think the red (12V accessory output 500mA) should be connected to "announce" itself? Or is that to power an accessory?

Interestingly, and I don't know if this means anything, the instructions show 6 wires come from the 12-pin connector into the auxilary unit, and mine only has 4???

[VU]

Hey, does anyone know where to get the jack in the picture from for your ipod.

It makes everthing look so nice and clean. Also where did the holder come from for the ipod.

I wanted to get all the info before I set up with the Ipod in my Hummer.

Then off to put one in the Mini. haha.

Vu

[TouchdownTN]

I'll be out of town this weekend, so I'll have to post the pics Monday. Really just a simple setup as far as the subs go. They are in a bandpass box that I bought a couple years ago for my Expedition. It takes up most of the space in the back of the H2. I did leave enough slack to move the box to the front when the seats are folded down, or I can just unplug the speaker wire and remove the box if needed. I'm really happy with the Ipod setup. I bought the Ipod cupholder and it works great having it so convienient to the factory headunit and being able to tuck the wire into the storage bin in the console. I will post pics ASAP but will be Monday before it is possible.

[Klaus]

Demystifying Class 2
By Karl Yama****a
March 4, 2003

A lot of installers, dealers and customers have asked many questions on Class 2 so I wrote this small article to clear some things up.

Introduction

What is Class 2 in GM vehicles that everyone is hearing about lately?
Class 2 or Class B is really a in-vehicle network SAE J1850 protocol that GM has been using for many years. It just a new data protocol that a majority of vehicle computer modules uses, which share the same single data wire through out the vehicle.
Recently GM has now included the driver’s door module, passenger’s door module, rear seat audio controller, vehicle communication interface module or OnStar®, steering wheel audio controls, rear seat entertainment (RSE), CD changer, radio, DVD/Video, amplifier and XM radio as part of Class 2. Since these new modules are part of the audio system and security system, you are now hearing more about Class 2.

Connected to this same data wire is the Body Control Module (BCM), Powertrain Control Module (PCM), Transfer Case Shift Control Module, Heater & A/C controls (HVAC), Inflatable Restraint Sensing and Diagnostic Module, Theft Deterrent Control Module, Memory Seat Module, Drivers Information Center (DIC), Key/Lights/Seatbelt Chimes (most vehicles), Instrument Panel Cluster (IPC), Suspension Control Module, Electronic Brake Control Module (EBCM) and other modules.

Frequently asked questions

Do all these modules communicate at the same time?
Yes they do. Each module on the bus has its own ID number and is sent out every two seconds as a state of health message (SOH) to let other modules know that it is present. Every module sends information to other modules when needed. When the ignition is first turned on, there could be as many as 100 or more messages sent on the data bus from various modules within 1 or 2 seconds.

How can all the modules communicate at the same time and not interfere with one another?
Well first, all the modules have a Data Link Controller (DLC) chip with and internal or external transceiver physically connected to the data bus. And second, each module is assigned a different level of priority. The DLC is the key to the Class 2 bus. It is designed to send and receive data depending on priority. When each modules sends information over the data bus, they also check to see if there is other data activity on the bus. If that module sees other data while it is sending data and it has low priority, it will stop sending and try again when the data bus is inactive.

What happens if one module goes bad or power is disconnected from it? Will it load down the data bus and disable crucial control modules like the PCM or BCM?
Again, the DLC chip or transceiver is the key. It is designed so that even if power is interrupted or it damaged, it will not affect the data bus. So lets say if the radio power was disconnected but it was still connected to the data bus, it will not interfere with any other control module’s communication on the data bus.

Does your product use the DLC chip?
Yes they do. We incorporate it in our products to insure your safety when you drive your vehicle. You may pay alot more for our products for Class 2, but is your life or family worth saving a few dollars?

Is it true that the factory radio is related to the airbags?
No. The factory has nothing to do with the airbags or any other modules. The airbags are controlled by the Inflatable Restraint Sensing and Diagnostic Module.

Why are the factory radios being relocated when installing an aftermarket stereo?
Some vehicles have chimes built into the radio. When ever the key is left in the key cylinder or parking lights left on, the radio sends audio chimes to the speakers or to amplifier (if equipped). If the radio is removed, there is no way for chimes to be heard. Seat belts are part of the chimes also, and if not retained could result in the driver not using the seatbelt. The retailer installing an aftermarket stereo could be liable for injuries if the driver was to get into an accident and not wearing a seatbelt.

Can using a test light on the data bus cause damage to modules on the bus?
No, the DLC chip or transceiver is short circuit protected to ground and to voltage spikes up to 40 volts. The worst thing that will happen is that modules will not be able to send SOH messages and data information. Basically the engine won't run unless the BCM, PCM and other modules can communicate to each other.

I've heard that one vehicle would not start if the factory radio was removed. I thought the radio has nothing to do with any engine control modules?
Currently we have not run into a vehicle that has this problem. We wonder if the installer had a wiring issue that may have disabled the data bus?

I tried to put a LOC at the headunit but the volume of the aftermarket amplifier does not vary with the radio volume. Why?
Some vehicles have fixed audio signal outputs going to the factory BOSE amplifier. The BOSE amp only accepts 2 channels of audio from the front outputs of the factory radio. The rear outputs of the factory radio go to the RSE. When you adjust the volume/fade/balance or even EQ settings, the factory radio sends data to the factory amplifier. The factory amplifier actually does all the fading/balancing and adjusts EQ settings directly.


All other information on the vehicles are confidential and cannot be disclosed.
If you would like more technicle information on Class 2, you may do a search on 'J1850 and/or Data Link Controller' on the web.





--------------------------------------------------------------------------------

Pacific Accessory Corporation
1502 S. Santa Fe St. • Santa Ana, CA 92705 • USA
Voice: (714)835-3022 • Fax: (714)835-3233
Copyright © 2002-2003 PAC • Designed by Tatung

http://www.pac-audio.com/mainpage/class2.htm

[TouchdownTN]

Well I finally got the PAC device installed. I had a friend of mine help me install it. I now have 2-10" Polk Subs hooked up to an aftermarket amp, and the 2 aux inputs with an Ipod on one of the inputs. So far I love it. Sound quality on the Ipod is night and day different compared to the I-trip FM device I have been using. We fit both the AAI-GM24 behind the radio on the right hand side and the C2A-GM24 behind the left hand side. It was a tight fit but my friend got it to fit. I have the cupholder Ipod holder and I ran the wire for the Ipod out of the center console so I can have it hidden when I want to remove the Ipod. Thanks for everyone's help!

[Zing]

Should the yellow wire be connected to "constant" power or only when the ignition switch is on. I don't feel comfortable with true constant power, nor do I see why that would be needed.

Thanks for you advice Klaus. My plan is to ask PAC a few of these questions and try again next Saturday.

[Klaus]

Which version do you have? There appears to be two versions of the adapter.

One with 12 and 24 pin connectors (older version):

http://www.pac-audio.com/instructions/aai-gm24.pdf

Newer version, 12 pin connectors only:

http://www.pac-audio.com/instruction...4-04.07.04.pdf

If you have the newer version, did you connect the yellow and black wires? Yellow needs constant 12v, and black is ground.

You will probably not use the Red and Orange wires, so they can be taped up and tied out of the way.

[Zing]

I have the new version and crap, no, I just taped up the extra wires. I read "if an auxilary source requires a 12 volt accessory" to mean if my MP3 player needed a 12 volt power input, then...

So do you and tap the actual wires? Like cut the wire coating and solder into it? Or do you somehow tap that plug they show in the instructions?

[TouchdownTN]

Well, I finally ordered my AAI-GM24. I also ordered the PAC device that allows you to hook up a aftermarket amp to the factory head unit. This will solve the problem of having to splice into the factory wiring. The unit that adds an amp has a harness to fit the head unit so I can splice the AAI-GM24 into the other harness instead of the factory wiring. I will let you know how the install goes. I'm going to do it myself and hope everything turns out right!

[Klaus]

4 wires are all that are needed to be "added" to the 12 pin connector. Those are L+, R+, and common audio, and a "drain" wire.

The real problem I see is that you are missing a connection to the Class 2 Data Bus. I wouldn't attempt to connect one of the other wires to it! You could really do some major damage to your truck's electronics! BTW, the airbags are tied into the Class 2 Data Bus! You did disconnect the battery, right?

My suggestion would be to temporarily connect the adapter up to test it. Just connect the yellow wire to battery + somewhere, and the black to ground. No need to solder, just run a jumper wire from some other 12v source (maybe the 12v power outlet connector). Then power up your radio to see what happens. Don't hook the red or orange wires to anything without first calling PAC!

I suspect you will be sending this unit back.

[TouchdownTN]

Don't know about that particular "jack" I use the Belkin Ipod Charger. I have it plugged into the rear 12V on the drivers side of the console. I then ran the wire up through the center console and out from the lid. I did have to enlarge a hole in the tray that sits in the center console. The Belkin charger plugs into the bottom of the Ipod. Where the charger plugs into the 12V it has a mini-plug to run the miniplug to RCA cable to the PAC device. I just ran my mini-plug to RCA cord through the center console and out of the back of the console to the Belkin charger. As for holding the Ipod I bought the cup holder Ipod holder. Got it on ebay for about $20 incl shipping. CompUSA carries both the holder and the Belkin Charger. Let me know if I can help you! My setup looks just like the ones in the pics above except for keeping the Ipod in the cupholder mount.

[Zing]

Plenty of room for the auxiliary unit, since you loop it over the left vent and then let it hang down the left side. Issue really is the bulk of new wires from connecting the unit. They don't reach to the top between the air vents. I shoved them down to the lower left. You'll see what I mean. It's not a big deal though. Took me 5 minutes to figure it out.

[jwm3]

3/4

[TouchdownTN]

Sorry about the pics not posting! Haven't posted pics before. I left my disc with photo's at work. I will try to post them Monday. I have to say JWM3's pics remind me of my install. I don't have any pics of the dash apart just where I mounted the I-pod, Amp, and Sub Box. Again, I apologize about the pics and will try it again!

[hummer17]

Zing / Klaus / JWM3:

Seems that the PAC device allows the radio to recognize the AUX source (in this case a MP3 player)...

Can the MP3 player then be controlled by the radio to select tracks, etc (or through the steering wheel)???

Does your radio display show the track name?

I've seen new interface units for the iPOD that do this with certain head units.

BMW even has an interface that is backwards compatible to 2003 models that allows an iPOD to be recognized as an external CD changer and displays the track name on the radio plus can be controlled (to some degree -you have to setup special playlists) through the radio controls and steering wheel controls while the iPOD is in the glove compartment...

JWM - what is the connector you are using - power and audio signal??

[PARAGON]

PICS?????

[Zing]

Thanks Klaus! That is actually very interesting.

[Klaus]

Zing,

You know what? Now that I look at the wiring and instructions, I wonder how this thing is going to work.

All the radio accessories I have seen need a connection to the GM Class 2 Data Bus to "announce" itself as an available device, so that the head unit will show it as an option. The GM 6 CD Changer, and the GM XM Radio Tuner does this.

The problem is, the "new" style PAC unit you have does NOT have a connection to the Class 2 Data Bus! The Class 2 Data Bus circuit is in the 24 pin connector (pin A1).

I think someone may have goofed on the re-design of this thing! I'll be real surprised if it works!

[Zing]

General radio question. Right now when I select "CD/Aux" nothing happens. Stays on FM. Or when I cycle through the bands using the "Band" button, no auxilary channel is displayed. Does this change when I hook up the PAC auxilary?