After servicing modules modules wont communicate.

Did you check all the fuses? Do that first. I mean EVERY fuse underhood and inside and with a METER not just visual. If they're good, lost communication is usually a sign of a shorted module on the data bus. Get a wiring diagram, locate all the modules on the data bus and unplug one at a time until you get communications back. Then replace that module.

HDM module ??????? No such module .
DTC U0100 00: Lost Communication With Engine/Powertrain Control Module (ECM/PCM)
DTC U0101 00: Lost Communication With Transmission Control Module (TCM)
DTC U0121 00: Lost Communication With Electronic Brake Control Module (EBCM)
DTC U0140 00: Lost Communication With Body Control Module (BCM)
DTC U0151 00: Lost Communication With Restraints Control Module
DTC U0155 00: Lost Communication With Instrument Panel Cluster (IPC) Control Module
DTC U0164 00: Lost Communication With HVAC Control Module
DTC U0168 00: Lost Communication With Vehicle Theft Deterrent (VTD) Control Module
DTC U0170 00: Lost Communication With Passenger Presence System (PPS)
DTC U0184 00: Lost Communication With Radio
DTC U0186 00: Lost Communication With Audio Amplifier
DTC U0194 00: Lost Communication With Digital Radio Receiver (DRR)
DTC U0198 00: Lost Communication With Communication Interface Module (OnStar®)
DTC U0209 00: Lost Communication With Heated Seat Module (HSM)
DTC U0214 00: Lost Communication With Remote Function Actuation (RFA)

These are all the modules onyour vehicle - no hdm module .

You need to take the vehicle an have a diagnostic scan of the control modules done . With the service staibiltrac on the system is disabled , an any number of thing's can cause system to shut down . With these systems the computer can change engine timing , RPM , valve timing etc.... All the modules on your vehicle share information , communicate on a serial data network .
The communication among control modules is performed through the High speed GMLAN serial data circuits and the Low speed GMLAN serial data circuit. The modules that need real time communication are attached to the High speed GMLAN network. The body control module (BCM) is the gateway between the high and low speed networks. Communication is necessary between the high and low speed serial data modules for the vehicle to start. Refer to Body Control System Description and Operation for more information about the gateway.
Signal supervision is the process of determining whether an expected signal is being received or not. Some messages are sent on a periodic basis and are interpreted as a heartbeat of a device. If such a signal is lost, the signal supervision part of the software will set a no communication DTC (U code) against the missing device. This code is mapped on the Tech 2 screen as a code against the physical device. A lost communication DTC typically is set in modules other than the module with a communication failure.
When thing's like the problem your having need to be diagnosed by a qualified repair facility . This is nothing for a DIYER to mess with .
When

With all of the electrical problems your having , your best bet would be to take it to a ASE certified repair shop ! Because the first place to start is hooking a professional grade scan tool to see if all the modules on the vehicle are communicating with the scan tool an each other ! I don't know the existent of your knowledge of your vehicle ! Your vehicle has at lest ten computers onboard an they all communicate on a serial data communication network , Class2 The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. This serial data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each other. Once the scan tool is connected to the class 2 serial data line through the DLC, the scan tool can be used to monitor each module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). Class 2 serial data is transmitted on a single wire at an average of 10.4 kbps. This value is an average, class 2 uses a variable pulse width modulation to carry data and depending on the message it may operate faster or slower. The bus will float at a nominal 7.0 volts during normal operation. Each module can pull this lower during the transmission. The bus is not at battery positive voltage or ground potential during normal operation. When the ignition switch is in RUN, each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating, for example, when the inflatable restraint sensing and diagnostic module (SDM) SOH message disappears, several modules set DTC U1088. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.
. The ignition on you caddy has a safety system known as
Electronic Park Lock (EPL)/Ignition Lock Cylinder Control Actuator for floor shift or
Linear Shift Assembly: If the vehicle is equipped with a column mounted gear shift, it has a linear shift assembly on the steering column. The linear shift assembly has a cable that runs from the linear shift assembly to the ignition lock cylinder case. The purpose of this cable is to prevent the ignition key from being turned to the OFF position when the transmission is in gear and the vehicle may still be moving. The linear shift assembly cable contains a pin that is spring loaded to mechanically prevent the ignition key cylinder from being turned to the lock position when the vehicle transmission is not in the PARK position. If vehicle power is lost, and/or the transmission is not in the PARK position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column.
On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the dash integration module (DIM). The PMM receives 2 signals from the ignition switch.
To determine the correct power mode the PMM uses the following circuits
?€¢
Accessory voltage

?€¢
Run/Crank voltage

Well ,that's because there is a problem with the system an there are What are call DTC'S -diagnostic trouble codes stored in the modules , computers ! You need to take to a repair facility that has a professional grade scan tool that can read codes in the body control module !
SERVICE VEHICLE SOON
The IPC illuminates the SERVICE VEHICLE SOON in the following conditions:
?€¢
The BCM detects certain malfunctions in the lighting system. The IPC receives a class 2 message requesting illumination from the BCM.

?€¢
The IPC detects a loss of class 2 communication with the BCM.

This year vehicle as with all newer vehicles have several control modules that control the engine , air bags , antilock brakes , anti-theft system ,Heating an air conditioning ,the instrument cluster an some others ! These modules are all connected on a class 2 serial data communication network so the modules can share information ! Your best bet is to take it to GM dealership or a ASE certified repair shop before you guess an just replace parts , that will cost you more in the long run !

"Loss of Serial Communication Link
Possible causes - Faulty Engine control Module (ECM)
- Engine control Module(ECM) harness is open or shorted
- Engine control Module (ECM) cicuit poor electricl connection
- Low battery voltage
Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light)"

Read more: http://engine-codes.com/p0600.html#ixzz3XWyqBac7

Take it an have vehicle scan done . Your vehicle has a vast amount of electronics , control modules , communication networks for the modules to share data on . All it takes is one of the wires touching ground to cause all kind of problems . There are modules inside the doors that control power windows , locks , mirrors etc. . Hooking up a scan tool that can check for communications from all modules . Not a code reader . A GM factory Tech 2 would be best . I work for Cadillac ,have for twenty years .

p169 is "no ccd bus mesages recieved" that means the engine OR trans computer has not seen any communication (called a BUS) from the other modules on the communication bus if the instrument cluster is not working then it is the source of the code if the car wont shift then there is a communication issue with the trans computer if it wont start then there is a problem with the engine computer communication this is usually set by a bad instrument cluster

The communication with SRS CM (Supplemental Restraint System Control Module) is proprietary - Hyundai Dealership Scanner equipment. Best solution: Take the vehicle into a Hyundai Service Center (dealership), pay the diagnostic fee. They will tell you EXACTLY what the problem is and what's needed to fix it (parts, labor, tax, time-frame, etc.).

"no bus" = if the instrument cluster show this in the odometer area- the vehicle electrical communication is not functioning. There is either a short in the wiring or one of the modules is causing the communication no to work. You need someone who knows how to check out the wiring and possible has a diagnostic tool that can communicate with modules in the vehicle. If you can check the faults - that would be the best way to start-it might me the ignition switch module.