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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1533 (DATA COMMUNICATION SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC U0100 - U0299 (HP2)CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:
  • Identify how to disable high voltage.
  • Identify how to test for the presence of high voltage.
  • Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Failure to follow the procedures exactly as written may result in serious injury or death.
    IMPORTANT: DTC U0125 may be set in the electronic brake control module (EBCM) due to the multi-axis acceleration sensor module (yaw rate/lateral accelerometer) communicating only on PTLAN serial data if there is a fault on that system. If U0074 or any U18xx exists in any module, diagnose those DTCs prior to DTC U0125.
    The multi-axis acceleration sensor module is not indicated on the scan tool as a communicating module. To check for communication on this module check EBCM data parameter Longitudinal Accelerometer Sensor Signal for correct reading.
  1. Verify the following DTCs are not present in the modules as follows:

    BCM

    • U1814
    • U2099
    • B1428
    • B1370
    • B1380
    • B1440
    • B1441

    HPCM

    • U1812
    • U189A

    SDGM

    • B137A
    • B137B
    • U0073
    • U0074
    • U182A
    • U209A
  2. Using the Hybrid High Voltage Module Chart below, verify that the non-communicating module is not a high voltage module.
    • If the module is a high voltage module, perform the High Voltage Disabling procedure before proceeding with this diagnostic.
  3. Reconnect the 12-volt battery.
  4. Ignition OFF, disconnect the necessary harness connectors of the non-communicating module.
  5. Test for less than 10 ohms between the module ground circuits and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
    6. IMPORTANT: Not all modules have an enable circuit OR wake up circuit. Refer to the module schematics to identify which modules have these circuits. If the module that is not communicating does not have one of these circuits, proceed to step 6.
  6. Ignition ON, verify that a test lamp illuminates between the serial data wake up or communication enable circuit, if equipped, and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the module that supplies voltage to the wake up or enable circuit.
  7. Ignition ON, verify that a test lamp illuminates between all B+ circuits and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the module.
  8. Verify that a test lamp illuminates between all ignition voltage circuits and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the module.
  9. Using the Hybrid High Voltage Module Chart below, verify that the module reporting the DTC is not a high voltage module.
  10. Reconnect the 12-volt battery.
  11. Ignition OFF, disconnect the harness connector containing the serial data circuits between the module that reported the DTC and the module reported as not communicating.
  12. Test for less than 1 ohm on the GMLAN serial data circuits between the non-communicating module and the module that displays the DTC.
    • If greater than the specified range, test the serial data circuit for open/high resistance.
  13. If all circuits test normal, replace the module that is not communicating.
Hybrid High Voltage Module Chart

Module Voltage System Data Link Type
Drive Motor Generator Power Inverter Module (PIM) (Includes Drive Motor Control Module (MCM) 1, 2 and Hybrid Powertrain Control Module (HPCM) ) 300V
12V
  • High Speed Hybrid GMLAN
  • High Speed GMLAN
Accessory DC Power Control Module (APM) 300V
42V
12V		 High Speed Hybrid GMLAN
Transmission Control Module (TCM) (RPO M99) 300V
12V		 High Speed GMLAN
Air Conditioning Control Module (ACCM) (Part of AC Compressor with HP2) 300V
12V		 Low Speed GMLAN
Drive Motor Generator Battery Control Module (BECM) 300V
12V		 High Speed GMLAN
Power Steering Control Module (PSCM) 42V
12V		 High Speed LAN
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.