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Makes 🢒 GMC_Truck 🢒 2005 🢒 GMC C Sierra - 2WD 🢒 Vehicle Control Systems 🢒 Computer/Integrating Systems 🢒 DTC U0100-U0299

DTC U0100-U0299 HP2

Circuit Description

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. There are two 120 ohm resistors between the GMLAN serial data (+) and (-) circuits. One is internal to the powertrain control module (PCM) and the other is internal to the energy storage control module (ESCM). When tested between the GMLAN serial data (+) and (-) circuits at the data link connector (DLC) with the ignition key OFF, normal resistance is 55-65 ohms.

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.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

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

Conditions for Running the DTCs

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

Conditions for Setting the DTC

A supervised periodic message that includes the transmitter module availability has not been received by powertrain control module (PCM) from 1 or more of the high speed GMLAN modules.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) may illuminate.
    • The Hybrid Engine Idle Off feature may not operate properly.

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

Diagnostic Aids

The following conditions may cause the DTC to set:

    • A poor connection or terminal tension at a GMLAN module
    • An intermittent open on either high speed GMLAN serial data circuit
    • An open voltage or ground circuit to a module
    • An internal module malfunction
    • A short between the GMLAN serial data circuits
    • A short to voltage or ground on either of the GMLAN serial data circuits

Test Description

The number below refers to the step number on the diagnostic table.

  1. A resistance out of range will indicate 1 of several specific faults as follows:

    2. • A high resistance indicates an open or high resistance in either of the high speed GMLAN serial data circuits between C 206 and the modules, including all module internals, circuits between, and module terminal tension.
    • A low resistance indicates a short between the high speed GMLAN serial data circuits, including module internals.
    • Infinite resistance indicates an open between the DLC and C 206 in either of the high speed GMLAN serial data circuits.

Step

Action

Values

Yes

No

Schematic Reference: Data Link Connector Schematics

Connector End View Reference: Master Electrical Component List and Inline Harness Connector End Views in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Important: Use the DMM MIN/MAX function to capture intermittent conditions.

  1. Ignition OFF.
  2. Test the resistance between data link connector (DLC) pins 14 and 6.

Is the resistance within the specified range?

55-65 ohms

Go to Step 3

Go to Step 13

3
  1. Turn ON the ignition, with the engine OFF.
  2. Install the scan tool with the CANdi module attached to it.
  3. Attempt to communicate with the following modules:
    4. • Energy storage control module (ESCM)
    • Starter/generator control module (SGCM)
    • Electro-hydraulic power steering (EHPS) module

Does the scan tool communicate with any of the listed modules?

--

Go to Step 9

Go to Step 4

4

Important: Turn ON the ignition, with the engine OFF, when testing for a short to voltage. Use the DMM MIN/MAX function to capture intermittent conditions.

Test the high speed GMLAN serial data circuits at the DLC for:

    • A short to ground
    • A short to voltage

Refer to the following in Wiring Systems:

    •  Circuit Testing

Did you find any of the above conditions?

--

Go to Step 5

Go to Step 9

5
  1. Disconnect the high speed GMLAN modules, one at a time, in the following order testing for the short found in the previous step after each disconnect:
    2. • powertrain control module (PCM)
    • Hybrid control module (HCM)
    • EHPS
    • SGCM
    • ESCM
  2. Test the high speed GMLAN serial data circuits at the DLC for the short found at step 4.

Does the short found at step 4 at DLC still exist?

--

Go to Step 8

Go to Step 6

6

Important: If only PCM was disconnected on step 5, answer No at this step.

Test the high speed GMLAN serial data circuits between the last 2 disconnected modules for the short found at step 4.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 7

7

Consider the last disconnected module as the non-communicating module for the following steps.

--

Go to Step 12

--

8

Repair the high speed GMLAN serial data circuits between DLC and ESCM/SGCM for the short found in step 4.

Refer to the following in Wiring Systems:

    •  Connector Repairs
    •  GMLAN Wiring Repairs

Did you complete the repair?

--

Go to Step 15

--

9

Important: Use the DTC Descriptors list in order to determine which module is not communicating.

Test the following circuits of the module that is not communicating for an open or a short to ground:

    • The battery positive voltage input circuits
    • The battery positive voltage output circuits
    • The ignition voltage input circuits
    • The ignition voltage output circuits
    • The switched battery positive voltage circuits

Refer to the following:

    •  Control Module References for the applicable schematic
    •  Circuit Testing in Wiring Systems
    •  Wiring Repairs in Wiring Systems

Did you find and correct the condition?

--

Go to Step 15

Go to Step 10

10
  1. Turn OFF the ignition.
  2. Test the ground circuits of the module that is not communicating for an open.

Refer to the following:

    •  Control Module References for the applicable schematic
    •  Circuit Testing in Wiring Systems
    •  Wiring Repairs in Wiring Systems

Did you find and correct the condition?

--

Go to Step 15

Go to Step 11

11

Test the high speed GMLAN serial data circuits of the module that is not communicating for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 12

12

Inspect the harness connectors of the module that is not communicating or is causing the malfunction for poor connections and terminal tension at the following circuits:

    • The battery positive voltage input circuits
    • The battery positive voltage output circuits
    • The ignition voltage input circuits
    • The ignition voltage output circuits
    • The switched battery positive voltage supply circuits
    • The ground circuits
    • The high speed GMLAN serial data circuits

Refer to the following:

    •  Control Module References for the applicable schematic
    •  Connector Repairs in Wiring Systems

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

13

Important: A circuit or module terminal tension is the likely fault. If a module does cause the malfunction, proceed to step 12.

Repair the high speed GMLAN serial data (+) or (-) circuit as necessary.

Did you find and correct the condition with a wiring repair?

--

Go to Step 15

Go to Step 12

14

Replace the module that is not communicating. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.
  3. Select the Display DTCs function for the module which was not communicating.

Does the scan tool display any DTCs which do not begin with a "U"?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 16

16

Select the Display DTCs function for the modules which had the Loss of Communications DTC set.

Does the scan tool display any DTCs which do not begin with a "U"?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 17

17
  1. Use the scan tool in order to clear the DTCs.
  2. Continue diagnosing or clearing the DTCs until all the modules have been diagnosed and all the DTCs have been cleared.

Did you complete the action?

--

System OK

--

DTC U0100-U0299 Diesel Engine

Circuit Description

Modules connected to the high speed GMCAN 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 high speed GMCAN 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 high speed GMCAN circuits are shorted to battery voltage, ground or between them, no communication is possible on high speed GMCAN serial data bus, and a DTC U0073 is set.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC U0100 Lost Communication With Engine Control Module (ECM)
    • DTC U0101 Lost Communication With Transmission Control Module (TCM)
    • DTC U0106 Lost Communication With Glow Plug Control Module (GPCM)
    • DTC U0105 Lost Communication With Fuel Injector Control Module (FICM)

Conditions for Running the DTCs
    • Voltage supplied to the modules is in the normal operating voltage range.
    • The engine is running.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets
    • The module uses a default value for the missing parameter.
    • 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 for the 6.6L (LLY) engine.

Conditions for Clearing the MIL/DTC

The MIL/DTC clearing depends on DTC type. For information about DTC types, refer to Diagnostic Trouble Code (DTC) Types for the 6.6L (LLY) engine.

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

Diagnostic Aids
    • A poor connection at the inoperative module may cause this code to set.
    • An improperly powered module may cause this code to set.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.

Step

Action

Yes

No

Schematic Reference: Data Link Connector Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Important: Use the DTC descriptor list in order to determine which module is not communicating on high speed GMCAN serial data bus.

  1. Turn the ignition ON, with the engine OFF.
  2. Test the following circuits of the module that is not communicating on high speed GMCAN serial data bus for an open or a short to ground:
    • The battery positive voltage input circuits
    • The battery positive voltage output circuits
    • The ignition voltage input circuits
    • The ignition voltage output circuits
    • The switched battery positive voltage circuits

Refer to the following:

    •  Control Module References for the applicable schematic
    •  Circuit Testing
    •  Wiring Repairs

Did you find and correct the condition?

Go to Step 8

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Test the ground circuits of the module that is not communicating on high speed GMCAN serial data bus for an open.

Refer to the following:

    •  Control Module References for the applicable schematic
    •  Circuit Testing
    •  Wiring Repairs

Did you find and correct the condition?

Go to Step 8

Go to Step 4

4

Test the high speed GMCAN serial data circuits of the module that is not communicating on high speed GMCAN serial data bus for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 8

Go to Step 5

5

Inspect the harness connectors of the module that is not communicating on high speed GMCAN serial data bus for poor connections and terminal tension at the following circuits:

    • The battery positive voltage input circuits
    • The battery positive voltage output circuits
    • The ignition voltage input circuits
    • The ignition voltage output circuits
    • The switched battery positive voltage supply circuits
    • The ground circuits
    • The high speed GMCAN serial data circuits

Refer to the following:

    •  Control Module References for the applicable schematic
    •  Connector Repairs

Did you find and correct the condition?

Go to Step 8

Go to Step 6

6

Replace the module that is not communicating on high speed GMCAN serial data bus. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 7

--

7
  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.
  3. Select the Display DTCs function for the module which was not communicating.

Does the scan tool display any DTCs which do not begin with a "U"?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 8

8

Select the Display DTCs function for the modules which had the Loss of Communications DTC set.

Does the scan tool display any DTCs which do not begin with a "U"?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 9

9

  1. Use the scan tool in order to clear the DTCs.
  2. Continue diagnosing or clearing the DTCs until all the modules have been diagnosed and all the DTCs have been cleared.

Did you complete the action?

System OK

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