I spoke to a technician at Soundgate yesterday. They design interfaces for radios, among other things. He gave me some very interesting information. The system that all newly designed GM cars use is called GM Lan. It is VERY complex. The BCM (body control module) sounds out a signal every 2 seconds and waits for a response from all components. This is called the 'State of Health Message'. If anything is not right, problems occur (like the diagnostics being messed up when you try to take a reading at service time). Without the proper circuity in the radio system, he said OnStar would not operate, as well as the steering wheel controls and the chimes. The chip GM uses is not available to the public yet. They are working on a adapter to solve these issues.

Regarding powering the new unit, (and my problem with finding ample amperage to power my air horns), he told me that GM uses wiring that is 'barely adequate'. There is NO SPARE CAPACITY on any circuits in the system. The wiring itself is of minimal gauge to support its load. ANY additional items will overload the circuit. In order to power a new head unit with an internal amp, he said you should run a line direct from the battery (and fused next to the battery).

I plan on running an 8 or 6 gauge line to the center console, then using a distribution block like for stereo systems then running an extension line to the engine compartment with another distribution block for my airhorns and any other things I add on.

Gotta love the new technology

 

I both love and hate new technology. The new hdtv that coming out is gonna be secured with hdcp...long story short, if you like hd and you bought your tv over a year ago your gonna have to buy a new one if u want to keep watching high def. Pretty crappy.

 

He is close, GM is migrating from Class II to GM LAN. The older Class II vehicle network was proprietary to GM but GMLAN is based on CAN (controller area network) which was developed by Bosh.

There are many companies making CAN hardware (Motorola, Intel) as either stand alone IC’s or CAN controllers integrated in to a microprocessor. Obviously you would need skills to design computer hardware and software to explore GMLAN.

You can buy devices that will allow you to tap into GMLAN (be careful, it is a balanced network) and see the messages that are flying around on the LAN. The problem here is that GM does not release the details of GMLAN messages. A CAN message is made up of either a 11 bit or a 29 bit message ID followed by up to 8 bytes of data.

The radio audio is used for chimes, turn signal click, and OnStar audio. There are companies that make adapters so you can retain these features with a new radio. I’ve done this in my Yukon and picked up the parts from Crutchfield.

If you have an interest to explore CAN, check out:
http://www.vector-cantech.com/

New technology is great, I think….

 

The power cable I used for my amp was 2 gauge, ran from the battery. I used the remote wire at the stock amp, and used a line level converter for the origional sub to send audio to the amp.

 

You ran the line level converter off of the sub wiring after it goes through the factory amp?

 

I think (hope) he meant BEFORE the amp. Some amps have 2 inputs-others can only take RCA and need conversion from the regular-wire signal. But in the past, I had a line level converter blow out my radio. When I checked its circuitry, there were two wires touching inside creating a dead short.

 

But if I remember correctly there was no wirirng for the sub before the amp?

 

I havent had mine apart yet-but the weather is getting nicer so it wont be long.

 

I ran the converter after the amp. That's what it is made for, converting high level output to low level (RCA). Come now do you really think the stock amp is "that" powerful.

 

I know it's not. I am going to amp mine soon. :) I was just trying to clear that up, not say your wrong in doing so.