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I'm just curious if your aware of the BCM function's on your vehicle an if you know what the gate way module is ? An do you know about serial data communication between modules ? An do you know what the power mode master is ? And do you know the BCM needs programming ?
The body control module (BCM) in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the GMLAN high speed buss and the GMLAN low speed buss for communication between the various modules. The gateway will interact with each network according to that network's transmission protocol.
One example of this necessary communication is the communication between the engine control module (ECM)/powertrain control module (PCM) which is high speed serial data and Theft Deterrent Module which is low speed serial data. If these modules can not exchange information, the vehicle will not start.
Communication between the BCM and a scan tool can be on the high speed GMLAN network or low speed GMLAN network. If one network is lost, the BCM can still communicate with the scan tool. A lost communication DTC typically is set in modules other than the module with a communication failure.
The first place to start with problems like this to try an reset the computers on the vehicle . Disconnect the battery cables an touch them together for five or ten min. Then if that doesn't work you need to have the vehicle checked out , which means having a factory or equivalent scan tool check for codes in the BCM !
The body control module (BCM) is capable of controlling multiple body functions. Components directly connected to the BCM are controlled by the BCM's outputs. The BCM controls the outputs based on input information that it obtains from the sensors and the switches that are directly connected to it. The BCM can also borrow information from other vehicle systems connected to the Class 2 serial data link. The BCM evaluates this information and controls certain body systems by commanding an output ON or OFF.
The BCM is also capable of commanding other vehicle systems to control functions that are not directly wired and/or controlled by the BCM. The BCM accomplishes this task by sending specific messages on the Class 2 serial data link. The vehicle system capable of performing such function will respond to the BCM message.
The BCM controls the following functions:
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Audible Warnings
You have upscale - luxury ?
It's separate from BCM .
Headlamp Control Module (Luxury)
Lower center of the IP, to the right of the right side steering column support bracket
Do your windshield wipers also stop working? If so, the most likely cause is your Body Control Module (BCM). The 1999-2000 GMC Denali was known for having issues with the retained accessory power relay solder connection inside the BCM. If you're up to the task of removing the BCM (located inside the center console- kind of a pain to get at) and know how to solder, you can fix it. Otherwise the BCM will have to be replaced.
Power for those devices is provided from the retained accessory power which is controlled by the BCM (body control module) which is in the console.I had the same problem with the radio, wipers and windows all stopping. I tried running the diag procedure for the BCM but couldn't get in to run. I then read online about a loose connection in the BCM, so I took the 4 screws out of the console, got access to the BCM and removed it. inside is a small circuit board. On the back of the circuit board where most of the soldering is, there was a bad connection to a relay. Re-soldered the connection and the problem went away.
Ok supper Dave , let's get this stright , when you turn the key to start the vehicle , what happens ? The starter spins the engine or doesn't spin the engine ? This would be a no crank no start condition . if the engine does spin an doesn't start an run this is a crank no start condition . Now which is it ? The factory radio is hooked to the serial data communication network , did you or who ever installed the aftermarket radio use a interface module ? Are you familiar with the electronics on this vehicle ? BCM - body control module , low current inputs from the ignition switch which determine what mode to put the vehicle in ?
The body control system consists of the body control module (BCM), communications, and various input and outputs. Some inputs, outputs and messages require other modules to interact with the BCM. The BCM also has discrete input and output terminals to control the vehicle's body functions. The BCM is wired to the GMLAN high speed serial data buss and the GMLAN low speed serial data buss and acts as a gateway between them. If the BCM does not communicate the vehicle will not start due to the inability of the engine control module (ECM)/powertrain control module (PCM) and theft deterrent module (TDM) to communicate without the BCM providing the gateway function.
Power Mode Master
This vehicles body control module (BCM) functions as the power mode master (PMM). The ignition switch is a low current switch with multiple discrete ignition switch signals to the PMM for determination the power mode that will be sent over the serial data circuits to the other modules that need this information, and so the PMM will activate relays and other direct outputs of the PMM as needed. Refer to Power Mode Description and Operation for a complete description of power mode functions.
Sorry but I am a GM Tech . have been for over thirty years , Cadillac , Buick an Chevy .audio buds think it's something else. Your audio buds don't have a clue ? When change something you better well know what your messing with. .
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