GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2008 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Power and Signal Distribution 🢒 Data Communications 🢒 Diagnostic System Check - Vehicle
  1. Before beginning vehicle diagnosis, the following preliminary inspections/tests must be performed:
    2. • Ensure that the battery is fully charged. Refer to Battery Inspection/Test .
    • Ensure that the battery cables are clean and tight.
    • Inspect for any open fuses. Refer to Power Distribution Schematics and Electrical Center Identification Views .
    • Ensure that the grounds are clean, tight, and in the correct location. Refer to Ground Distribution Schematics and Harness Routing Views .
    • Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the concern. This would include checking to ensure that all connections/connectors are fully seated and secured.
    • Inspect for aftermarket devices that could affect the operation of the system. Refer to Checking Aftermarket Accessories .
    • Search for applicable service bulletins.
    ⇒If the preceding inspections/tests resolve the concern, go to Diagnostic Repair Verification .
  2. Install a scan tool. Verify that the scan tool powers up.
    3. ⇒If the scan tool does not power up, refer to Scan Tool Does Not Power Up .
  3. Ignition ON, Engine OFF, verify communication with all of the control modules on the vehicle. Refer to Data Link References for information on the modules you should expect to communicate.
    4. ⇒If the scan tool does not communicate with one or more of the expected control modules, refer to Data Link References .
  4. Attempt to start the engine. Verify that the engine cranks.
    5. ⇒If the engine does not crank, refer to Symptoms - Engine Electrical .

    Important: For the 7.2L Caterpillar engine, refer to the appropriate Caterpillar Service Manual.

  5. Attempt to start the engine. Verify the engine starts and idles.
    6. ⇒If the engine does not start and idle, refer to one of the following:
    •  Engine Cranks But Does Not Run for the 6.6L (LMM) engine
    •  Engine Cranks But Does Not Run for the 7.8L (LF8) engine
    •  Engine Cranks But Does Not Run for the 8.1L engine

    Important: For the 7.2L Caterpillar engine, refer to the appropriate Caterpillar Service Manual.

    Important: Do not clear any DTCs unless instructed to do so by a diagnostic procedure.

    Important: If any DTCs are Powertrain related DTCs, select Capture Info in order to store the DTC information with the scan tool.

  6. Use the appropriate scan tool selections to obtain DTCs from each of the vehicle modules. Verify there are no DTCs reported from any module.
    7. ⇒If any DTCs are present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and diagnose any current DTCs in the following order:
    6.1. DTCs that begin with a U.
    6.2. Any of the following: B1000, B1001, C0550, P0601, P0602, P0603, P0604, P0605, P0606, P060B, P061C, P062C, P062F, P064C, P160C, P1621, P2108, or P2610.
    6.3. Any of the following: C0899, C0900, P0562, or P0563.
    6.4. Component level DTCs.
    6.5. System level DTCs.
    6.6. Any remaining DTCs.
  7. If none of the previous tests or inspections addresses the concern, refer to Symptoms - Vehicle .