Data Link Communication System: Diagnosis Chevrolet Silverado 3500

Diagnostic Starting Point - Data Link Communications

Begin the diagnosis of the Data Link Communications by performing the Diagnostic System Check for the system in which the customer concern is apparent. The Diagnostic System Check will direct you to the correct procedure within the Data Link Communications section when a communication malfunction is present.

Diagnostic Trouble Code (DTC) List

Diagnostic Trouble Code (DTC) List

Circuit Description

Modules connected to the controller area network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. If no communication is detected on the CAN serial data circuit, the DTC is set. A total non-communication condition may be caused by a short to battery or voltage on any of the CAN circuits or a short between the CAN high and low circuits.

The following modules communicate on CAN serial data (LLY engine)

1. The engine control module (ECM)
2. The transmission control module (TCM)
3. The fuel injector control module (FICM)
4. The glow plug control module (GPCM)

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC U0073 High Speed CAN Communication Bus

Conditions for Running the DTCs

1. Voltage supplied to the modules is in the normal operating voltage range.
2. The engine is running.

Conditions for Setting the DTC

A total non-communication condition is detected on the CAN serial data circuit.

Action Taken When the DTC Sets

1. The module uses a default value for the missing parameter.
2. The malfunction indicator lamp (MIL) will illuminate on the second consecutive ignition cycle that the diagnostic runs and fails, for the type B DTCs. For a detailed description about DTC types, refer to «Diagnostic Trouble Code (DTC) Type Definitions»(ref-184141-S33780120672005082200000) in Engine Controls - 6.6L (LLY).

Conditions for Clearing the MIL/DTC

The MIL/DTC clearing depends on DTC type. For information about DTC type, refer to Diagnostic Trouble Code (DTC) Type(s) in Engine Controls - 6.6L (LLY)

DTC Type B

1. The MIL clears after 3 ignition cycles when the malfunction is no longer present.
2. A current DTC clears when the malfunction is no longer present.
3. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC Type C

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC U0073

Modules connected to the controller area network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuit malfunction or which loses power during the current ignition cycle will have a Loss of Communication DTC set by other modules that depend on information from that failed module. If any of the CAN circuits are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a DTC U0073 is set.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC U0100 Lost Communication With Engine Control Module (ECM)
2. DTC U0101 Lost Communication With Transmission Control Module (TCM)
3. DTC U0105 Lost Communication With Fuel Injector Control Module (FICM)
4. DTC U0106 Lost Communication With Glow Plug Control Module

1. Voltage supplied to the modules is in the normal operating voltage range.
2. The engine is running.

A supervised periodic message that includes the transmitter module availability has not been received.

1. The module uses a default value for the missing parameter.
2. The malfunction indicator lamp (MIL) will illuminate on the second consecutive ignition cycle that the diagnostic runs and fails, for the type B DTCs. For a detailed description about DTC types, refer to «Diagnostic Trouble Code (DTC) Type Definitions»(ref-184141-S33780120672005082200000) in Engine Controls - 6.6L (LLY).

The MIL/DTC clearing depends on DTC type. For information about DTC types, refer to Diagnostic Trouble Code (DTC) Type(s) in Engine Controls - 6.6L (LLY).

DTC Type B

1. The MIL clears after 3 ignition cycles when the malfunction is no longer present.
2. A current DTC clears when the malfunction is no longer present.
3. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC Type C

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Diagnostic Aids

1. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. When a message that indicates the availability of the transmitter module is not received, the receiver module sets a DTC.

This diagnostic procedure supports the following DTCs

1. DTC U0111 Lost Communication With Energy Storage Control Module (ESCM)
2. DTC U0120 Lost Communication With Starter/Generator Control Module (SGCM)
3. DTC U0131 Lost Communication With Electro-Hydraulic Power Steering (EHPS) Module
4. DTC U0293 Lost Communication With Hybrid Control Module (HCM)

Voltage supplied to the modules is in the normal operating voltage range.

A supervised periodic message that includes the transmitter module availability has not been received by the powertrain control module (PCM) from any of the high speed GMLAN modules.

The module uses a default value for the missing parameter.

1. The malfunction indicator lamp (MIL) clears after 3 ignition cycles when the malfunction is no longer present.
2. A current DTC clears when the malfunction is no longer present.
3. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

The following conditions may cause the DTC to set

1. A poor connection at the inoperative module
2. An intermittent open on high speed GMLAN
3. An open voltage or ground circuit to a module
4. An internal module malfunction

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, DTC U1000 is set. When more than one critical parameter does not have an identification number associated with it, the DTC will only be reported once.

The class 2 serial data line on this vehicle is a star configuration, with the body control module (BCM) and powertrain control module (PCM) each have a second class 2 serial data line between them. The following modules communicate on the class 2 serial data line

1. The audio amplifier
2. The body control module (BCM)
3. The digital radio receiver (DRR)
4. The driver door module (DDM)
5. The driver seat module (DSM)
6. The electronic brake control module (EBCM)
7. The front passenger door module (FPDM)
8. The HVAC control module
9. The hybrid control module (HCM), for PHT
10. The inflatable restraint sensing and diagnostic module (SDM)
11. The instrument panel cluster (IPC)
12. The powertrain/engine control module (PCM/ECM)
13. The radio
14. The rear seat audio (RSA) controller
15. The rear seat entertainment (RSE) assembly w/U42
16. The rear wheel steering control module (RWSCM)
17. The remote playback device-CD player (CDX) w/U1S
18. The transfer case shift control module (TCSCM)
19. The transmission control module (TCM) w/Allison transmission
20. The vehicle communication interface module (VCIM) w/UE1

Conditions for Running the DTC

1. Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
2. DTCs U1300, U1301 or U1305 do not have a current status.
3. The vehicle power mode requires serial data communication to occur.

A node alive message has not been received from an unidentified module within the last 5 seconds after establishing class 2 serial data communication.

The module uses a default value for the missing parameter.

Conditions for Clearing the DTC

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

When a malfunction occurs while modules are communicating, a lost communication DTC is set as a current DTC. When the modules stop communicating the current lost communication DTC is cleared but the history DTC remains. When the modules begin to communicate again, the module with the open fuse will not be learned by the other modules so U1000 is set current by the other modules. If the malfunction occurs when the modules are not communicating, only U1000 is set.

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that modules node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a DTC U1XXX. XXX is equal to the 3 digit identification number of the module.

The control module ID number list provides a method for determining which module is not communicating. A module with an internal class 2 serial data circuit malfunction or which loses power during the current ignition cycle would have a lost communication DTC set by other modules. Use the control module ID number list in order to determine which module is not communicating and the lost communications with XXX diagnostic table in order to diagnose the malfunction. When no message is detected from a learned identification number for 5 seconds, a DTC U1XXX is set.

Module ID

When more than one loss of communication DTC is set in a single module or among multiple modules, diagnose the DTCs in the following order

1. Current DTCs before history DTCs except as specified in the diagnostic tables.
2. The DTC which is reported the most times.
3. From the lowest number DTC to the highest number DTC.

1. Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
2. DTCs U1300, U1301 or U1305 do not have a current status.
3. The vehicle power mode requires serial data communication to occur.

A node alive message has not been received from a module with a learned identification number within the last 5 seconds.

The module uses a default value for the missing parameter.

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

1. An intermittent open between a module and a star connector may cause this DTC to set.
2. A poor connection at a module or a star connector may cause this DTC to set.
3. An intermittent open in a star connector may cause this DTC to set.
4. An open voltage or ground circuit to a module may cause this DTC to set.
5. An internal module malfunction may cause this DTC to set.

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. When the module detects one of the following conditions on the class 2 serial data circuit for approximately 3 seconds, the setting of all other class 2 serial communication DTCs is inhibited and a DTC will set.

DTC U1300, U1301, or U1305

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

1. These DTCs cannot be retrieved with a current status. Diagnosis of current DTCs is accomplished via the symptom, Scan Tool Does Not Communicate with a Class 2 Device. Refer to «Scan Tool Does Not Communicate with Class 2 Device»(ref-184111-S29155650642005082200000) .
2. An intermittent condition is likely to be caused by a short on the class 2 serial data circuit. Use the Scan Tool Does Not Communicate with a Class 2 Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with Class 2 Device»(ref-184111-S29155650642005082200000) .

Modules connected to the controller area network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication DTC set by other modules that depend on information from that failed module. If any of the CAN circuits are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a DTC U2104 is set.

This diagnostic procedure supports the following DTCs

1. DTC U1800 Lost Communications With Fuel Injector Control Module (FICM)
2. DTC U2105 Lost Communications With Engine Control Module (ECM)
3. DTC U2106 Lost Communications With Transmission Control Module (TCM)

1. Voltage supplied to the modules is in the normal operating voltage range.
2. The engine is running.

A supervised periodic message that includes the transmitter module availability has not been received.

1. The module uses a default value for the missing parameter.
2. The malfunction indicator lamp (MIL) will illuminate on the second consecutive ignition cycle that the diagnostic runs and fails, for the type B DTCs. For a detailed description about DTC types, refer to «Diagnostic Trouble Code (DTC) Type Definitions»(ref-184141-S33780120672005082200000) in Engine Controls - 6.6L (LB7).

The MIL/DTC clearing depends on DTC type. For information about DTC types, refer to Diagnostic Trouble Code (DTC) Type(s) in Engine Controls - 6.6L (LB7).

DTC Type B

1. The MIL clears after three ignition cycles when the malfunction is no longer present.
2. A current DTC clears when the malfunction is no longer present.
3. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC Type C

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

1. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

Modules connected to the class 2 and high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. All DTCs in this range are reported on class 2 link to the scan tool by powertrain control module (PCM) even if they may be set by different modules.

This diagnostic procedure supports the following DTCs

1. DTC U1881 Electro-Hydraulic Power Steering (EHPS) Module Lost Communication With Energy Storage Control Module (ESCM)
2. DTC U1882 Energy Storage Control Module (ESCM) Lost Communication With Electro-Hydraulic Power Steering (EHPS) Module
3. DTC U1883 Hybrid Control Module (HCM) Lost Communication With Driver Door Module (DDM)
4. DTC U1884 Hybrid Control Module (HCM) Lost Communication With Passenger Door Module (PDM)
5. DTC U1885 Energy Storage Control Module (ESCM) Lost Communication With Hybrid Control Module (HCM)
6. DTC U1886 Energy Storage Control Module (ESCM) Lost Communication With Powertrain Control Module (PCM)
7. DTC U1887 Energy Storage Control Module (ESCM) Lost Communication With Starter/Generator Control Module (SGCM)
8. DTC U1888 Hybrid Control Module (HCM) Lost Communication With Energy Storage Control Module (ESCM)
9. DTC U1889 Hybrid Control Module (HCM) Lost Communication With Body Control Module (BCM)
10. DTC U1890 Hybrid Control Module (HCM) Lost Communication With HVAC Control Module
11. DTC U1891 Hybrid Control Module (HCM) Lost Communication With Instrument Panel Cluster (IPC)
12. DTC U1892 Hybrid Control Module (HCM) Lost Communication With Electro-Hydraulic Power Steering (EHPS) Module
13. DTC U1893 Hybrid Control Module (HCM) Lost Communication With Powertrain Control Module (PCM)
14. DTC U1894 Hybrid Control Module (HCM) Lost Communication With Starter/Generator Control Module (SGCM)
15. DTC U1895 Electro-Hydraulic Power Steering (EHPS) Module Lost Communication With Powertrain Control Module (PCM)
16. DTC U1896 Electro-Hydraulic Power Steering (EHPS) Module Lost Communication With Starter/Generator Control Module (SGCM)
17. DTC U1897 Starter/Generator Control Module (SGCM) Lost Communication With Energy Storage Control Module (ESCM)
18. DTC U1898 Starter/Generator Control Module (SGCM) Lost Communication With Hybrid Control Module (HCM)
19. DTC U1899 Starter/Generator Control Module (SGCM) Lost Communication With Powertrain Control Module (PCM)

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

A node alive message has not been received from an identified module within the last 5 seconds after establishing class 2 serial data communication, or a supervised high speed GMLAN message has not been received.

The module uses a default value for the missing parameter.

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

1. An intermittent open between a module and a star connector may cause this DTC to set.
2. An intermittent open on high speed GMLAN may cause this DTC to set.
3. An open voltage or ground circuit to a module may cause this DTC to set.
4. An internal module malfunction may cause this DTC to set.

Modules connected to the controller area network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. If no communication is detected on CAN serial data circuit, the DTC is set. A total non-communication condition may be caused by a short to battery or voltage on any of the CAN circuits or a short between the CAN high and low circuits.

The following modules communicate on CAN serial data (LB7 engine)

1. The engine control module (ECM)
2. The transmission control module (TCM), w/M74
3. The fuel injector control module (FICM)

This diagnostic procedure supports the following DTC

DTC U2104 Controller Area Network (CAN) Bus Reset Counter Overrun

1. Voltage supplied to the modules is in the normal operating voltage range.
2. The engine is running.

A total non-communication condition is detected on CAN serial data circuit.

1. The module uses a default value for the missing parameter.
2. The malfunction indicator lamp (MIL) will illuminate on the second consecutive ignition cycle that the diagnostic runs and fails, for the type B DTCs. For a detailed description about DTCs types refer to «Diagnostic Trouble Code (DTC) Type Definitions»(ref-184141-S33780120672005082200000) in Engine Controls - 6.6L (LB7).

The MIL/DTC clearing depends on DTC type. For information about DTC type refer to Diagnostic Trouble Code (DTC) Type(s) in Engine Controls - 6.6L (LB7).

DTC Type B

1. The MIL clears after 3 ignition cycles when the malfunction is no longer present.
2. A current DTC clears when the malfunction is no longer present.
3. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC Type C

1. A current DTC clears when the malfunction is no longer present.
2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC U2104

Symptoms - Data Link Communications

1. Perform the applicable diagnostic system check before using the symptom tables in order to verify that there are no DTCs set.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to «Data Link Communications Description and Operation»(ref-184111-S40349252892005082200000) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the systems. Refer to «Checking Aftermarket Accessories»(ref-184114-S31353837752005082200000) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Scan Tool Does Not Power Up»(ref-184111-S09291524662005082200000)
2. «Scan Tool Does Not Communicate with Class 2 Device»(ref-184111-S29155650642005082200000)
3. «Scan Tool Does Not Communicate with High Speed GMLAN Device»(ref-184111-S34336812862005082200000)

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following

1. Scan tool power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5

The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.

The engine will not start when there is a total loss of class 2 serial data communication while the ignition is OFF. The following conditions will cause a total loss of class 2 serial data communication

1. A class 2 serial data circuit shorted to ground.
2. A class 2 serial data circuit shorted to voltage.
3. An internal condition within a module or connector on the class 2 serial data circuit, that causes a short to voltage or ground to the class 2 serial data circuit.

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications on the high speed GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules.

The scan tool communicates with the following modules via the high speed GMLAN

1. The energy storage control module (ESCM)
2. The starter/generator control module (SGCM)
3. The electro-hydraulic power steering (EHPS) module

The following conditions may cause a total loss of high speed GMLAN data communication

1. A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
2. Any of the high speed GMLAN serial data circuits shorted to ground or voltage
3. A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits

Scan Tool Does Not Communicate with High Speed GMLAN Device

The serial data communication among the control modules is performed through multiple serial data communication links. The class 2 serial data line is always present. The high speed GMLAN or controller area network (CAN) may be present for different vehicle options. The data link connector (DLC) allows a scan tool to communicate with the modules on class 2 or high speed GMLAN serial data lines. In order for the scan tool to communicate with the modules on high speed GMLAN link, a CANdi module is needed. The CANdi module behaves as an interface between the scan tool and the high speed GMLAN data link. The CAN is used for functional communication only, among the modules connected to it.