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Data Link Communication System: Overview Hummer H2 I

Communication Devices 5 illustrations ~752 words

Data Link Communications Schematic Icons Icon Icon Definition CAUTION: When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling Zones. Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs

Scheme 1

Scheme 1: Data Link Connector (DLC) Schematics

Scheme 2

Scheme 2

Scheme 3

Scheme 3: Data Link Communications Component Views
CalloutComponent Name
1BCM-C1
2BCM-C2
3BCM-C4
4BCM-C3
5BCM-C5
6Body Control Module (BCM)
7Footwell Courtesy Lamp-Left (If Equipped)
8Data Link Connector (DLC)
9Fuse Block-IP-C1
10Fuse Block-IP Center Block
11Splice Pack SP205

Scheme 4

Scheme 4
CalloutComponent Name
1Steering Column
2Transfer Case Shift Control Module
3Splice Pack SP206
4Steering Wheel Controls Backlight Fuse

Scheme 5

Scheme 5
CalloutComponent Name
1C200
2Splice Pack SP207
3C201
4Left Side Cowl Panel

Test Description

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

  1. 1: A DTC U1001 - U1254 Lost Communications with XXX with a history status may indicate the cause of U1000.
  2. 2: The modules not communicating are the likely cause of U1000. The modules that are available on the class 2 serial data circuit are listed in the Circuit Description.
  3. 6: The module which was not communicating due to a poor connection to the class 2 serial data circuit may have set DTC U1001 - U1254 Lost Communications with XXX for those modules that it was monitoring.
  4. 9: The modules which can communicate indicate the module which cannot communicate. You must clear the serial data communication DTCs from these modules to avoid future misdiagnosis.
  5. 12: If all modules are communicating, the module which set U1000 may have done so due to some other condition.
  6. 14: The module which set U1000 is the likely cause of the malfunction.
StepActionYesNo
Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Master Electrical Component List and Inline Harness Connector End Views in Wiring Systems
1Install a scan tool. Turn ON the ignition, with the engine OFF. Record the DTCs set in by each module. If using a Tech 2, use the Class 2 DTC Check feature to determine which modules have DTCs set. Did you record any DTCs in the range of U1001-U1254 with a history status?Go to Diagnostic Trouble Code (DTC) ListGo to Step 2
2Turn ON the ignition, with the engine OFF. Attempt to communicate with each module on the class 2 serial data circuit. If using a Tech 2, obtain this information using the class 2 Message Monitor feature. Record all of the modules communicating on the class 2 serial data circuit. Compare the list of modules which are communicating to the list given in Circuit Description. Does any module on the class 2 serial data circuit not communicate?Go to Step 3Go to Step 12
3Test the following circuits of the module that is not communicating for an open or short to ground: The battery positive voltage supply circuits The switched battery positive supply circuits The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits Refer to the following: Control Module References in Body Control System for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition?Go to Step 8Go to Step 4
4Turn OFF the ignition. Test the ground circuits of the module that is not communicating for an open. Refer to the following: Control Module References in Body Control System for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition?Go to Step 8Go to Step 5
5IMPORTANT: Inspect all connectors in the serial data communications circuit. Refer to the following: Data Link Connector (DLC) Schematics Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems Turn OFF the ignition. Test the class 2 serial data circuits of the module that is not communicating for an open. Refer to the following: Data Link Connector (DLC) Schematics Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition?Go to Step 8Go to Step 6
6Inspect the harness connector of the module that is not communicating for poor connections and terminal tension at the following circuits: The battery positive voltage input circuits The switched battery positive voltage supply The battery positive voltage output circuits The ignition voltage input circuits The ignition voltage output circuits The ground circuits The class 2 serial data circuits Refer to the following: Control Module References in Body Control System for the applicable schematic Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems Did you find and correct the condition?Go to Step 8Go to Step 7
7IMPORTANT: Perform the module programming or setup procedure if required. Replace the module that is not communicating. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for the module replacement.Did you complete the replacement?Go to Step 10
8Install a scan tool. Turn ON the ignition, with the engine OFF. 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 Control Module References in Body Control System for applicable Diagnostic System CheckGo to Step 9
9Use the scan tool in order to clear the DTCs. Did you complete the action?Go to Step 10
10Select the Display DTCs function for the modules which had U1000 set as a current DTC. Does the scan tool display DTCs which do not begin with a "U"?Go to Control Module References in Body Control System for applicable Diagnostic System CheckGo to Step 11
11Use the scan tool in order to clear the DTCs. Did you complete the action?System OK
12Did you record any other DTCs for the modules which had U1000 set as a current DTC?Go to Control Module References in Body Control System for applicable Diagnostic System CheckGo to Step 13
13Install a scan tool. Turn ON the ignition, with the engine OFF. Use the scan tool in order to clear the DTCs. Turn OFF the ignition for at least 5 seconds. Turn ON the ignition with the engine OFF. Select the Display DTCs function. Does the scan tool display U1000 set as a current DTC?Go to Step 14Go to Diagnostic Aids
14IMPORTANT: Perform the module programming or setup procedure if required. Replace the module which had U1000 set as a current DTC. Refer to Control Module References in Body Control System for the appropriate Repair Instructions for the module replacement.Did you complete the replacement?System OK
IMPORTANT
Inspect all connectors in the serial data communications circuit. Refer to the following: Data Link Connector (DLC) Schematics Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems
IMPORTANT
Perform the module programming or setup procedure if required.
IMPORTANT
Perform the module programming or setup procedure if required.

DTC U1000

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

  1. 6: The module which was not communicating on the class 2 serial data circuit may have set Loss of Communication DTCs for those modules that it was monitoring.
StepActionYesNo
Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Master Electrical Component List and Inline Harness Connector End Views in Wiring Systems
1IMPORTANT: Use the control module ID number 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 in Body Control System for the applicable schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition?Go to Step 6Go to Step 2
2Turn OFF the ignition. Test the ground circuits of the module that is not communicating for an open. Refer to the following: Control Module References in Body Control System for the applicable Schematic Circuit Testing in Wiring Systems Wiring Repairs in Wiring Systems Did you find and correct the condition?Go to Step 6Go to Step 3
3Test the class 2 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 6Go to Step 4
4Inspect the harness connectors of the module that is not communicating 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 class 2 serial data circuits Refer to the following: Control Module References in Body Control System for the applicable schematic Testing for Intermittent Conditions and Poor Connections in Wiring Systems Connector Repairs in Wiring Systems Did you find and correct the condition?Go to Step 6Go to Step 5
5IMPORTANT: Perform the programming or set up procedure for the module, if required. Replace the module that is not communicating. Refer to Control Module References for the applicable replacement procedure.Did you complete the replacement?Go to Step 6
6Install a scan tool. Turn ON the ignition with the engine OFF. 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 Control Module References for the applicable Diagnostic System CheckGo to Step 7
7Select 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 Control Module References for the applicable Diagnostic System CheckGo to Step 8
8Use the scan tool in order to clear the DTCs. 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?Go to Control Module References for the applicable Diagnostic System Check
IMPORTANT
Use the control module ID number list in order to determine which module is not communicating.
IMPORTANT
Perform the programming or set up procedure for the module, if required.

DTC U1001-U1254

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

  1. 4: If the battery positive voltage and ground circuits of the DLC are functioning properly. The malfunction must be due to the scan tool.
StepActionYesNo
Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Data Link Communications Connector End Views
1Test the battery positive voltage circuit of the data link connector (DLC) for an open or a short to ground. Refer to Circuit Testing or Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 2
2Test the ground circuit from pin 4 of the DLC for an open or high resistance. Refer to Circuit Testing or Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 3
3Inspect for poor connections and terminal tension at the DLC. Refer to Testing for Intermittent Conditions and Poor Connections or Connector Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 4
4The scan tool may be malfunctioning. Refer to the scan tool user guide. Did you obtain a properly operating scan tool?Go to Control Module References in Body Control System for the applicable Diagnostic System Check

Scan Tool Does Not Power Up

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

  1. 2: A partial malfunction in the class 2 serial data circuit uses a different procedure from a total malfunction of the class 2 serial data circuit. The following modules communicate on the class 2 serial data circuit: Air Suspension Module (ESC) Audio Amplifier (early production), refer to «Radio/Audio System Description and Operation»(ref-187213-S02333852502005083100000) in Entertainment for more information. BCM DDM DSM EBCM FPDM HVAC Control Module IPC PCM Radio RSA Module SDM TCSCM VCIM
  2. 3: The following DTCs may be retrieved with a history status, but are not the cause of the present condition. U1300 U1301 U1305
  3. 6: A state of health DTC with a history status may be present along with a U1000 or U1255 code having a current status. This indicates that the malfunction occurred when the ignition was ON.
  4. 7: Data link connector terminals 2 and 5 provide the connection to the class 2 serial data circuit and the signal ground circuit respectively.
  5. 10: A poor connection at DLC terminal of the splice pack - SP205 would cause this condition but will not set a DTC.
  6. 11: An open in the class 2 serial data circuit between the DLC and splice pack - SP205 will prevent the scan tool from communicating with any module. This condition will not set a DTC.
  7. 12: The class 2 serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wire for a short, make sure there is not a module connected to the wire being tested. This test isolates the BCM and the PCM class 2 serial data circuits.
  8. 13: This test isolates the BCM class 2 serial data circuits.
  9. 16: The BCM detects that the ignition is ON and sends the appropriate power mode message to the other modules. Therefore, the BCM must remain connected to the DLC for any other module to communicate with the scan tool. This test isolates the splice pack - SP207 serial data circuits.
  10. 21: This test isolates the splice pack - SP206 serial data circuits and radio.
  11. 28: This test isolates the EBCM and TCSCM class 2 serial data circuits.
  12. 32: This test isolates the rest of the splice pack - SP205 serial data circuits.
  13. 36: If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.
  14. 37: The communication malfunction may have prevented diagnosis of the customer complaint.
StepActionYesNo
Schematic Reference: Data Link Connector (DLC) Schematics Connector End View Reference: Master Electrical Component List and Inline Harness Connector End Views in Wiring Systems
1Does the scan tool power up?Go to Step 2Go to Scan Tool Does Not Power Up
2Turn ON the ignition leaving the engine OFF. Attempt to communicate with each module on the class 2 serial data circuit. If using a Tech 2, obtain this information using the Class 2 Message Monitor feature. Does the scan tool communicate with any module on the class 2 serial data circuit?Go to Step 3Go to Step 8
3Select the Display DTCs function for each module. If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules do have DTCs set. Record all of the displayed DTCs, the DTC status and the module which set the DTC. Did you record any DTCs in the range of U1000 to U1305?Go to Step 4Go to Step 7
4Are the history DTCs U1300, U1301 or U1305 retrieved from any module?Go to Step 5Go to Step 6
5IMPORTANT: 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 class 2 serial data circuit for an intermittent short to ground or an intermittent short to voltage. Refer to the following: Testing for Intermittent Conditions and Poor Connections Circuit Testing Connector Repairs Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 6
6Is U1000 or U1255 the only DTC displayed in the previously specified range?Go to DTC U1000Go to DTC U1001-U1254
7Diagnose the non-communicating module by using the DTC U1001-U1254 procedure for the module which is not communicating. Refer to DTC U1001-U1254 Did you complete the action?Go to Control Module References in Body Control System for the applicable Diagnostic System Check
8Turn OFF the ignition. Disconnect the scan tool from the data link connector (DLC). Inspect for poor connections at the DLC terminals 2 and 5. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 9
9Test the DLC ground circuit at terminal 5 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 10
10Disconnect the splice pack - SP205. Inspect for poor connections at the splice pack - SP205. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 11
11Test the class 2 serial data circuit between the DLC and the splice pack - SP205 for an open, a short to ground, or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Control Module References in Body Control System for the applicable Diagnostic System CheckGo to Step 12
12Using the correct terminal adapter, connect a jumper wire to the DLC terminal of the splice pack - SP205. Connect the other end of the jumper wire, using correct terminal adapter, to the BCM terminal of the splice pack - SP205. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 16Go to Step 13
13Turn OFF the ignition. Disconnect the PCM. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 14Go to Step 15
14Turn OFF the ignition. Test the class 2 serial data circuit between the splice pack - SP205 and the PCM for an open, a short to ground, or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 34
15Turn OFF the ignition. Disconnect the BCM. Test both class 2 serial data circuits of the BCM for an open, a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 34
16Leave the jumper wire connected to the DLC terminal and to the BCM terminal of the splice pack - SP205. Connect another jumper wire from the jumper wire connected to the DLC terminal of the splice pack - SP205. Connect the other end of the jumper wire, using correct terminal adapter, to the splice pack - SP207 terminal of the splice pack - SP205. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 21Go to Step 17
17Disconnect the splice pack - SP207. Inspect for poor connections at the splice pack - SP207. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 19Go to Step 18
18Repair the class 2 serial data circuit for a short to ground or a short to voltage between the splice pack - SP205 and the splice pack - SP207. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36
19Repeat the following steps on the class 2 serial data circuits connected to the splice pack - SP207 until the concern is located: Connect another jumper wire to the splice pack - SP205 terminal of the splice pack - SP207. Connect the other end of the jumper wire, using correct terminal adapter, to the terminal for the devices connected to splice pack - SP207. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 36Go to Step 20
20Turn OFF the ignition. Disconnect the module that caused the no communication condition. Test the class 2 serial data circuit between the splice pack - SP207 and the respective module for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 34
21Disconnect the jumper wire from the splice pack - SP207 terminal of the splice pack - SP205. Connect the jumper wire to the splice pack - SP206 terminal of the splice pack - SP205. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 28Go to Step 22
22Turn OFF the ignition. Disconnect the radio. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 34Go to Step 23
23Test the class 2 serial data circuit between the splice pack - SP205 and the radio for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find the condition?Go to Step 36Go to Step 24
24Disconnect the splice pack - SP206. Inspect for poor connections at the splice pack - SP206. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 26Go to Step 25
25Repair the class 2 serial data circuit for a short to ground or a short to voltage between the splice pack - SP205 and the splice pack - SP206. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36
26Repeat the following steps on the class 2 serial data circuits connected to the splice pack - SP206 until the concern is located: Connect another jumper wire to the splice pack - SP205 terminal of the splice pack - SP206. Connect the other end of the jumper wire, using correct terminal adapter, to the terminal for the devices connected to splice pack - SP206. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 36Go to Step 27
27Turn OFF the ignition. Disconnect the module that caused the no communication condition. Test the class 2 serial data circuit between the splice pack - SP205 and the respective module for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 34
28Disconnect the jumper wire from the splice pack - SP206 terminal of the splice pack - SP205. Connect the jumper wire to the EBCM terminal of the splice pack - SP205. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 32Go to Step 29
29Turn OFF the ignition. Disconnect the EBCM. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 34Go to Step 30
30Turn OFF the ignition. Disconnect the TCSCM. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 34Go to Step 31
31Repair the class 2 serial data circuit between the splice pack - SP205 and either the EBCM or TCSCM for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair?Go to Step 36
32Repeat the following steps on the class 2 serial data circuits connected to the splice pack - SP205 until the concern is located: Disconnect the jumper wire from the EBCM terminal of the splice pack - SP205. Connect the jumper wire, using correct terminal adapter, to the terminal for the rest of devices connected to splice pack - SP205. Turn ON the ignition leaving the engine OFF. Attempt to communicate with the BCM. Does the scan tool communicate with the BCM?Go to Step 36Go to Step 33
33Turn OFF the ignition. Disconnect the module that caused the no communication condition. Test the class 2 serial data circuit between the splice pack - SP205 and the respective module for a short to ground or a short to voltage. Turn ON the ignition leaving the engine OFF when testing for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 34
34Inspect for poor connections at the class 2 serial data circuit of the last disconnected module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?Go to Step 36Go to Step 35
35IMPORTANT: Perform the module setup procedure if required. Replace the last disconnected module. Refer to Control Module References in Body Control System for the appropriate repair instructions.Did you complete the replacement?Go to Step 36
36Reconnect all of the disconnected modules. Reconnect any other disconnected connectors. Install a scan tool. Turn ON the ignition leaving the engine OFF. Wait for 10 seconds. The scan tool may require a power up reset before communication will occur due to a short on the class 2 serial data circuit. Turn OFF the scan tool prior to performing this test. Select the Display DTCs function for each module. If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules do have DTCs set. Record all of the displayed DTCs and the DTC status. Did you record any DTCs which begin with a "U" and with a current status?Go to Step 38Go to Step 37
37Did you record any DTCs which do not begin with a "U"?Go to Step 38Go to Step 40
38Diagnose the DTCs as directed by the diagnostic procedures for the particular module or malfunction. Refer to Control Module References in Body Control System for the applicable Diagnostic System Check. Did you complete the action?Go to Step 39
39Did you diagnose all of the DTCs?Go to Step 40Go to Step 38
40Use the scan tool in order to clear the DTCs. Did you complete the action?System OK
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.
IMPORTANT
Perform the module setup procedure if required.

Scan Tool Does Not Communicate with Class 2 Device