Diagnostic System Check - Vehicle
- Before beginning vehicle diagnosis, the following preliminary inspections/tests must be performed:
- 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 Power and Grounding Component Views .
- Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the concern.
- 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 .
- Install a scan tool. Verify that the scan tool powers up.
- If the scan tool does not power up, refer to Scan Tool Does Not Power Up .
- 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.
- If the scan tool does not communicate with all of the expected control modules, refer to Data Link References .
- Access the Power Mode parameter on the scan tool. Verify the power mode parameter matches all the ignition switch positions. Refer to Power Mode Description and Operation
for information on the power mode states that correspond to each ignition switch position.
- If the power mode parameter does not match the ignition switch position for all ignition switch positions, refer to Power Mode Mismatch .
- Attempt to start the engine. Verify that the engine cranks.
- If the engine does not crank, refer to Symptoms - Engine Electrical .
- Attempt to start the engine. Verify the engine starts and idles.
- If the engine does not start and idle, refer to one of the following:
- Engine Cranks but Does Not Run for the 4.2L engine
- Engine Cranks but Does Not Run for the 5.3L engine
- Engine Cranks but Does Not Run for the 6.0L engine
- If the engine does not start and idle, refer to one of the following:
- Use the appropriate scan tool selections to obtain DTCs from each of the vehicle modules. Verify there are no DTCs reported from any module.
- If any DTCs are present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and diagnose any current DTCs in the following order:
- DTCs that begin with a U.
- Any of the following: B1000, B1001, B1004, B1007, B1009, B2734, C0240, C0374, C0550, P0601, P0602, P0603, P0604, P0606, P0607, P062F, P1621, P2101 or P2610.
- Any of the following: P0562 or P0563.
- Component level DTCs.
- System level DTCs.
- Any remaining DTCs.
- If any DTCs are present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and diagnose any current DTCs in the following order:
- If the customer concern is related to inspection/maintenance (I/M) testing, refer to one of the following:
- Inspection/Maintenance (I/M) System Check for the 4.2L engine
- Inspection/Maintenance (I/M) System Check for the 5.3L engine
- Inspection/Maintenance (I/M) System Check for the 6.0L engine
- If none of the previous tests or inspections addresses the concern, refer to Symptoms - Vehicle .
IMPORTANT:
Open the drivers door to ensure retained accessory power mode (RAP) is inactive during this test. The engine may start during this test. Turn the engine OFF as soon as the crank power mode has been observed.
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.