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OK...so I just exploded my brain cramming in all the new GMT-900 entertainment/electrical wiring/electrical systems/data bus info on ACDelco TDS. Seriously I just am so interested in this stuff my brain goes into super cram mode...I just read about 100 pages of tech data and entertainment pinouts and descriptions in about half an hour and I already ahve everything memorized!!

But ok...enough of my boring life.

So whats the deal with GMLAN? Is it in any compatible with our GMT-800 trucks? How does it work? Is it similar in function (token ring? is it a serial data bus?) to Class II??

Reason im wondering is Im eyeing that Bose 5.1 system in the new Escalade. The 5.1 special amp (RPO code Z75, yeah I already have that memorized too) needs "GMLAN low speed data". Is there any way...any way at all...to make GMLAN components work in our GMT-800 trucks? I know im "a nut" as bobo says :) but I really want to check all this stuff out in person and tinker around with it...and learn all I can about this new GMLAN data bus...from what ive read everything down to the stupid dome light is in communication with the BCM...it just boggles my mind how integrated the GMT-900's are. Incredible vehicles under the skin if you ask me... Now I have to go back to convincing my dad to trade in his 03 Tahoe on a new 2007 one so I can take it all apart.):h

--Ben
 

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Ben, I sure do hope you study for your classes as much as you do your Duramax. ):h Try sleeping at night instead of posting at 2 AM !! Hope to see your headlights this week :ro)
 

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:lol: yeah I was up doing homework and needed a break so I just had to post that question...

Let me know when you want to check out those headlights...ill also show you what a blown turbo sounds like! :D
 

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Ben, where are the drivers located in a 5.1 truck, and is it physicaly the same location of the amp Ill check with Specmo
 

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Ben, where are the drivers located in a 5.1 truck, and is it physicaly the same location of the amp Ill check with Specmo
I have pics of it all. Amp is in the same location (center console) as is the sub. However Im looking over pinouts for the Z75 (Bose 5.1 Dolby D/DTS amp) amplifier and it says soemthing about a rear subwoofer....so maybe the Bose 5.1 systems have a monstor sub in the rear as opposed to the cetner console sub on all the other Bose systems? The center speaker is located smack in the middle of the dash, firing up at the windshield. The Door speakers are in the same locations. Front a-pillar tweeters are in the same location. Rear d-pillar twiddlers are in the same location. And they are wired as before too. In parallel with the rear door speakers in the Tahoe/Burban/non-lux systems and wired to separate "midrange" channels on the amplifeir in the LUXURY systems. IM still trying to figure out whether the amps on the Tahoe/non lux vehicles communicate on the data bus. It seems there is two different non-lux Bose systems.:confused: UQA and UQ3 I think. I think one might be for DVD/RSE equipped vehicles and one is for non-RSE vehicles?? One communicates on the GMLAN bus and the other only has an "amplifier control wire". Im thinking its a simple gain control from the head unit? So it operates on the same therory as GMT-800 lux amps...fixed output from the head unit and volume is varied in the amp...only its not done thru data bus, its done witha simple gain control wire. The old 1995-2002 radios used a system like this I THINK... I know they had an "amp gain control wire". Whether the audio left the head unit at a fixed level on those old radios, I dont know... Ill read more tonight if I get my homeowrk done. Because I just love this stuff so much, I can read it at about a million miles an hour and soak up every bit, so Im hoping ill have the whole deal figured out by tonight.:D Ill let you guys know what I find.

--Ben

btw base audio systems (UQ5) are unchanged. They are amplified internally to the head unit as before.
 

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Someone needs a girlfriend;)

LOL:joke:
 

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Discussion Starter #7
haha yeah tell me about it....I really should NOT be occupying my time by reading this stuff :rolleyes:
 

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oh boy...hope this one wont go OT... :)
 

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I reccomend an easy clean up model
 

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Here is a quick cut and paste for you


GMLAN High Speed Circuit Description


The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit. The serial data is transmitted on two twisted wires that allow speed up to 500 Kb/s. The twisted pair is terminated with two 120 ohms resistors, one is internal to the powertrain control module (PCM) or engine control module (ECM) depending on regular production option (RPO) and the other is internal to the body control module (BCM). The BCM is considered the DLC termination point of the link and the engine management controller is the other end of the link. The resistors are used to reduce noise on the High Speed GMLAN buss during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level, which is approximately 2.5 volts, is considered recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes, adds one volt to the high speed GMLAN serial data bus (+) and subtracts one volt from the high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0. GMLAN network management supports selective start up and is based on virtual networks. A virtual network is a collection of signals started in response to a vehicle event. The starting of a virtual network signifies that a particular aspect of the vehicles functionality has been requested. A virtual network is supported by virtual devices, which represents a collection of signals owned by a single physical device. So, any physical device can have one or more virtual devices. The signal supervision is the process of determining whether an expected signal is being received or not. Failsofting is the ability to substitute a signal with a default value or a default algorithm, in the absence of a valid signal. Some messages are also interpreted as a heartbeat of a virtual device. If such a signal is lost, the application will set a no communication code against the respective virtual device. This code is mapped on the Tech 2 screen as a code against the physical device. Note: a loss of serial data DTC does not represent a failure of the module that the code is set in.


<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1549241&evc=sm&pubid=1197&cellId=72871&mspsdsubkey=5183#ss3-1549241">GMLAN Low Speed Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the low speed GMLAN serial data circuit. The serial data is transmitted over a single wire to the appropriate control modules. The transmission speed for GMLAN low speed is up to 83.33 Kb/s. Under normal vehicle operating conditions, the speed of the buss is 33.33 Kb/s. This protocol produces a simple pules train sent out over the GMLAN low speed serial data bus. When a module pulls the buss high, 5 volts, this creates a dominant logic state or 0 on the buss. When the buss is pulled low 0 volts, it is translated as a recessive logic state or 1. To wake the control modules connected to the GMLAN low speed serial data buss, a high voltage wake up pulse is sent out over the buss, the voltage level of the pules is +10 volts. Modules connected to the GMLAN low speed buss can be part of a virtual network as described in the previous paragraph. The modules on the GMLAN low speed serial data buss are connected to the buss in a parallel configuration.
 

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Discussion Starter #15
wow...im not gonna lie...that description completely lost me! :)

I udnerstand Class II inside and out, but GMLAN confuses the heck outta me...

So does it work like a computer LAN with its twisted pair...like with packet transmission and stuff like that..? Im lost!

Ben
 

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Discussion Starter #17

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Bac To The Future
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I think that GMLAN explanation MAY have touched a couple hairs as it flew over my head.


Let's see if I have this right:
Since Class2 or CAN use only 1 wire, the modules can only talk one at a time, but GMLAN is a
data communication that utilizes 2 wires so modules can converse back and forth at the same time?
 

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Here is a quick cut and paste for you


GMLAN High Speed Circuit Description


The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit. The serial data is transmitted on two twisted wires that allow speed up to 500 Kb/s. The twisted pair is terminated with two 120 ohms resistors, one is internal to the powertrain control module (PCM) or engine control module (ECM) depending on regular production option (RPO) and the other is internal to the body control module (BCM). The BCM is considered the DLC termination point of the link and the engine management controller is the other end of the link. The resistors are used to reduce noise on the High Speed GMLAN buss during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level, which is approximately 2.5 volts, is considered recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes, adds one volt to the high speed GMLAN serial data bus (+) and subtracts one volt from the high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0. GMLAN network management supports selective start up and is based on virtual networks. A virtual network is a collection of signals started in response to a vehicle event. The starting of a virtual network signifies that a particular aspect of the vehicles functionality has been requested. A virtual network is supported by virtual devices, which represents a collection of signals owned by a single physical device. So, any physical device can have one or more virtual devices. The signal supervision is the process of determining whether an expected signal is being received or not. Failsofting is the ability to substitute a signal with a default value or a default algorithm, in the absence of a valid signal. Some messages are also interpreted as a heartbeat of a virtual device. If such a signal is lost, the application will set a no communication code against the respective virtual device. This code is mapped on the Tech 2 screen as a code against the physical device. Note: a loss of serial data DTC does not represent a failure of the module that the code is set in.


<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1549241&evc=sm&pubid=1197&cellId=72871&mspsdsubkey=5183#ss3-1549241">GMLAN Low Speed Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the low speed GMLAN serial data circuit. The serial data is transmitted over a single wire to the appropriate control modules. The transmission speed for GMLAN low speed is up to 83.33 Kb/s. Under normal vehicle operating conditions, the speed of the buss is 33.33 Kb/s. This protocol produces a simple pules train sent out over the GMLAN low speed serial data bus. When a module pulls the buss high, 5 volts, this creates a dominant logic state or 0 on the buss. When the buss is pulled low 0 volts, it is translated as a recessive logic state or 1. To wake the control modules connected to the GMLAN low speed serial data buss, a high voltage wake up pulse is sent out over the buss, the voltage level of the pules is +10 volts. Modules connected to the GMLAN low speed buss can be part of a virtual network as described in the previous paragraph. The modules on the GMLAN low speed serial data buss are connected to the buss in a parallel configuration.


Ya that's exactly what I thought it was.













:lol:
:nopics:
:smashfrea
:duh:
:Nothing_f



PS, I vote for a girlfriend for Ben too
 

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Bac To The Future
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Ya, Ben needs to go find a woman....
 
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