Engine Controls - Trouble Shooting - No Codes - 6.6L: Other Chevrolet Silverado 1500 HD

Possible Causes & Corrections

Check the following items

1. Compare scan tool data at idle with scan tool data list. See «PIN VOLTAGE CHARTS - SILVERADO & SIERRA»(ref-157358) article.
2. Observe Fuel Rail Pressure (FRP) sensor and fuel pressure regulator commanded percent at idle. FRP should be near 40 MPa, and commanded percent should be near 40 percent. If command is high, a fuel pressure or sensor problem exists.
3. Inspect for an intermittent Crankshaft Position (CKP) sensor signal.
4. Inspect CKP sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
5. Perform engine compression test. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(ref-152810-S17987481152003022600000) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
6. Inspect engine for improper valve timing, bent push rods, worn rocker arms, worn camshaft lobes, or broken or weak valve springs.
7. Inspect intake and exhaust manifold passages for casting flash.
8. Inspect for plugged fuel filter, high vacuum, air in fuel system, etc.
9. Inspect for water contamination in fuel.
10. Inspect fuel injectors for proper operation. Perform Fuel Injector Balance Test using a Tech 2 scan tool.

Check the following items

1. Ensure customer has an actual problem.
2. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
3. Inspect fuel quality.
4. Observe the actual vs. desired fuel rail pressure with a scan tool, with engine running.
5. Inspect fuel injectors using Tech 2 scan tool.
6. Inspect Engine Coolant Temperature (ECT) sensor. Use scan tool in order to compare ECT with the ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in coolant sensor circuit or the sensor itself.
7. Inspect glow plug system operation.
8. Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with engine off. FRP should be 1.1-1.4 MPa. If not, inspect for high resistance in the low reference or 5-volt reference circuits or the sensor.
9. Inspect for a restriction in the air cleaner or air intake ducts.
10. Inspect for a restriction in the turbocharger charge air cooler.
11. Inspect for a restriction in the intake manifold.
12. Inspect for an air leak in the charge air cooler with a Charge Air Cooler Tester (J-46091).
13. Inspect for an air leak in the air ducts between turbocharger and intake manifold.
14. Inspect for incorrect basic engine parts such as the camshafts, cylinder heads, pistons, etc.
15. Inspect for excessive oil entering the combustion chamber.

Check the following items

1. Ensure customer has an actual problem.
2. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
3. Inspect fuel quality.
4. Observe the actual vs. desired fuel rail pressure with a scan tool, with engine running.
5. Inspect fuel injectors using Tech 2 scan tool.
6. Inspect Engine Coolant Temperature (ECT) sensor. Use scan tool in order to compare ECT with the ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in coolant sensor circuit or the sensor itself.
7. Inspect the glow plug system operation.
8. Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with engine off. FRP should be 1.1-1.4 MPa. If pressure is not within the specified range, inspect for high resistance in the low reference or 5-volt reference circuits or the sensor, or a faulty sensor.
9. Inspect air cleaner and air intake ducts for restriction.
10. Inspect for contamination of the Mass Airflow (MAF) sensor.
11. Inspect for a restriction in the turbocharger charged air cooler.
12. Inspect for a restriction in the intake manifold.
13. Perform a cylinder leakage test.
14. Perform engine compression test. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(ref-152810-S17987481152003022600000) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
15. Inspect for incorrect basic engine parts such as the camshafts, cylinder heads, pistons, piston rings and valves.
16. Inspect for excessive oil entering the combustion chamber.
17. Inspect for leaking seals in turbocharger. A slight film on intake side is normal.

Check the following items

1. Ensure customer has an actual problem.
2. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
3. Inspect fuel quality.
4. If excessive smoke is present, inspect for a stuck open fuel injector by performing the following procedure: Remove ignition 1 relay. Remove glow plugs. NOTE: Do not stand in front of glow plug holes while cranking engine. Crank engine while observing glow plug holes for fuel spray. Replace fuel injectors for cylinders that spray fuel. Inspect for contaminated oil or high oil level. Inspect fuel injectors using Tech 2 scan tool.
5. Inspect Engine Coolant Temperature (ECT) sensor. Use scan tool in order to compare the ECT with the ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in coolant sensor circuit or the sensor itself.
6. Inspect glow plug system operation.
7. Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with ignition on, and engine off. FRP reading should be 1.1-1.4 MPa. If pressure is not within the specified range, inspect for high resistance in the low reference or 5-volt reference circuits, or a faulty FRP sensor.
8. Inspect air cleaner and air intake ducts for restriction.
9. Inspect for a restriction in the turbocharger charge air cooler.
10. Inspect for a restriction in the intake manifold.
11. Inspect the Intake Air Heater (IAH) for proper operation. Use scan tool to command the IAH on and off. See DTC P0540 and P0543. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158516-S25875883752003100300000) in SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.
12. Inspect for incorrect basic engine parts such as the camshafts, cylinder heads, pistons, etc.
13. Inspect for coolant entering the combustion chamber.

Check the following items

1. Ensure vehicle has an actual problem.
2. Inspect fuel quality.
3. Inspect for smoke associated with the combustion noise.
4. Inspect for obvious overheating problems.
5. Inspect for a low engine coolant level.
6. Inspect for any restricted air flow through the radiator.
7. Inspect for a malfunctioning or incorrect thermostat.
8. Inspect for a correct coolant solution. The solution should be a 50/50 mix of anti-freeze and water.
9. Inspect Engine Coolant Temperature (ECT) sensor by using scan tool in order to compare ECT with ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or the sensor itself.
10. Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with ignition on, with engine off. FRP reading should be 1.1-1.4 MPa. If FRP is not within this range, check for high resistance in the low reference or 5-volt reference circuits or the sensor, or a faulty sensor.
11. Inspect for an intermittent Crankshaft Position (CKP) sensor signal.
12. Inspect CKP sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
13. If excessive smoke is present, check for a stuck open fuel injector by performing the following procedure: Remove ignition 1 relay. Remove glow plugs. NOTE: Do not stand in front of glow plug holes while cranking engine. Crank engine while observing glow plug holes for fuel spray. Replace fuel injectors for cylinders that spray fuel. Check for fuel in the oil and proper oil level.
14. Inspect for incorrect basic engine parts such as camshafts, cylinder heads, pistons, etc.
15. Inspect for any excessive oil entering combustion chamber.
16. Review Service Bulletins for control module software updates.
17. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.

Check the following items

1. Ensure vehicle operator is using correct starting procedure.
2. Inspect Engine Coolant Temperature (ECT) sensor. Use scan tool to compare ECT with ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in the coolant sensor circuit or the sensor itself.
3. Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with engine off. FRP reading should be 1.1-1.4 MPa. If not , inspect for high resistance in the low reference, 5-volt reference circuits, or FRP sensor.
4. Inspect the Crankshaft Position (CKP) sensor reluctor wheel. Remove the CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement the reluctor wheel retaining bolts are loose.
5. Inspect the fuel pressure regulator 12-volt circuit for an intermittent short to ground. Observe the FRP Command percent while cranking. A range of 85-95 percent indicates a possible short to ground condition.
6. Inspect the fuel supply to the fuel injection pump.
7. Inspect for a restricted fuel filter.
8. Inspect for air in the fuel system.
9. Inspect for external fuel leaks.
10. Inspect for high engine oil level.
11. Inspect fuel return from the fuel injection pump.
12. Inspect fuel injectors. Perform Fuel Injector Balance Test using a Tech 2 scan tool.
13. Inspect fuel tank cap vent for proper operation.
14. Inspect glow plug system for proper operation.
15. Inspect for a slow cranking speed.
16. Inspect air cleaner and air intake ducts for a restrictions or leaks.
17. Inspect for a restriction in turbocharger inlet duct.
18. Inspect for a restriction or a leak in the intake manifolds.
19. Inspect exhaust system for a possible restriction.
20. Improper valve timing.
21. Bent push rods.
22. Worn rocker arms.
23. Low engine compression. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(ref-152810-S17987481152003022600000) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
24. Broken or weak valve springs.
25. Worn camshaft lobes.
26. Inspect for an intermittent CKP signal.
27. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
28. Check Service Bulletins for control module software updates.

Check for the following items

1. Inspect the fuel supply system vacuum.
2. Inspect for water contamination in the fuel.
3. Perform Fuel Injector Balance Test using a Tech 2 scan tool.
4. Inspect for high fuel supply system vacuum after a cold start or during moderate or full throttle acceleration. If the vacuum jumps above specification, there is a restriction in fuel system.
5. Inspect Fuel Rail Pressure (FRP) sensor. Observe the FRP with a scan tool. The FRP reading should be between 1.1-1.4 MPa. If not, inspect for high resistance in FRP sensor circuits or FRP sensor.
6. Test for an intermittent FRP sensor signal by wiggling the harness between sensor and ECM with ignition on, engine off, while monitoring the parameter with a scan tool.
7. Observe FRP sensor and fuel pressure regulator commanded percent at idle. FRP should be near 40 MPa, and commanded percent should be near 40 percent. If command is high, a fuel pressure or sensor problem exists.
8. Inspect for an intermittent Crankshaft Position (CKP) sensor signal.
9. Inspect CKP sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
10. Check Service Bulletins for control module software updates.
11. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
12. Inspect generator output voltage.

Check the following items

1. Compare vehicle with a similar unit. Ensure vehicle has an actual problem.
2. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
3. Remove air filter and check for dirt. Check for plugged or leaking air ducts. Repair or replace as necessary.
4. Inspect for a proper transmission operation.
5. Inspect fuel quality.
6. Inspect engine oil level and quality.
7. Observe Fuel Rail Pressure (FRP) sensor and fuel pressure regulator commanded percent at idle. FRP should be near 40 MPa, and commanded percent should be near 40 percent. If command is high, a fuel pressure or sensor problem exists.
8. Inspect Crankshaft Position (CKP) sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
9. Inspect fuel supply to the fuel injection pump. See FUEL SYSTEMS in «BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL»(ref-152810) article.
10. Observe the actual vs desired fuel rail pressure with a scan tool, with engine idling.
11. Inspect engine speed signal circuit for high resistance.
12. Inspect for restricted or plugged fuel injectors. Perform Fuel Injector Balance Test using a Tech 2 scan tool.
13. Inspect exhaust system for a possible restriction. See «RESTRICTED EXHAUST»(ref-152999-S40493166652003031000000) .
14. Inspect for an air leak or restriction in air inlet ducts or intake manifold.
15. Inspect for an air leak or restriction in the charge air cooler using a Charge Air Cooler Tester (J-46091).
16. Inspect for a worn or damaged turbocharger turbine wheel, shaft or compressor wheel.
17. Inspect for a skewed Mass Airflow (MAF) sensor. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158516-S25875883752003100300000) in SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.
18. Check low compression. See CYLINDER COMPRESSION PRESSURE under «MECHANICAL INSPECTION»(ref-152810-S17987481152003022600000) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
19. Improper valve timing.
20. Improper or worn camshaft.
21. Inspect control module grounds for being clean, tight, and in their proper location.
22. Inspect Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
23. Inspect air conditioning system for proper operation. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
24. Inspect generator output voltage.

Check the following items

1. Inspect air filter for dirt or being plugged.
2. Inspect for an air leak in the charge air cooler with a Charge Air Cooler Tester (J-46091).
3. Inspect vacuum hoses for splits, restrictions, and improper connections.
4. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158516-S25875883752003100300000) in SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.
5. Inspect air conditioning system for proper operation. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
6. Inspect tires for correct air pressure.
7. Inspect driver's driving habits.
8. Are heavy loads being carried?
9. Suggest to driver to fill the fuel tank and inspect the fuel economy.
10. Suggest to driver to read the Important Facts on Fuel Economy in the Owner's Manual.
11. Check fuel type and quality.
12. Inspect engine coolant level.
13. Inspect engine thermostat for always being open or for wrong heat range.
14. Inspect transmission for proper operation.
15. Inspect Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. When TCC is commanded ON, a scan tool should indicate an RPM drop.
16. Inspect Service Bulletins for control module software updates.
17. Inspect brake for proper operation.

Check the following items

1. Search for bulletins.
2. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
3. Inspect ECM grounds for being clean, tight and in the proper locations.
4. Remove and inspect air filter element for dirt or for being restricted.
5. Inspect Fuel Rail Pressure (FRP) sensor. Observe FRP with scan tool. The FRP should be between 1.1-1.4 MPa. If not, inspect for high resistance in FRP sensor circuits or FRP sensor.
6. Test for an intermittent FRP sensor signal by wiggling the harness between the sensor and ECM with ignition on and engine off, while monitoring parameter with scan tool.
7. Observe FRP sensor and fuel pressure regulator commanded percent at idle. FRP should be near 40 MPa, and commanded percent should be near 40 percent. If command is high, a fuel pressure or sensor problem exists.
8. Inspect for an intermittent Crankshaft Position (CKP) sensor signal.
9. Inspect CKP sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
10. Inspect for proper crankcase ventilation. See «EMISSION SYSTEMS & SUB-SYSTEMS»(ref-153295-S25415696282003033100000) in SYSTEM & COMPONENT TESTING - 6.6L SIERRA & SILVERADO - DIESEL article.
11. Perform fuel injector balance test using a Tech 2 scan tool.
12. Inspect for a restricted fuel filter.
13. Inspect for a restriction in fuel return system.
14. Inspect for a contaminated fuel condition.
15. Inspect for a sticking fuel pressure regulator. The symptom for this condition will be an idle surge of at least 100 RPM. This surge will be from 50 RPM above or below the desired idle speed. See «FUEL SYSTEM DIAGNOSIS - HIGH PRESSURE SIDE»(ref-152810-S21775685432003022800000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
16. Inspect engine mechanical for cylinder compression. Low compression can be caused by sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, or broken valve springs. Check for excessive oil in the combustion chamber, caused by leaking valve seals.
17. Inspect for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, connecting rods, or bearings.
18. Inspect exhaust system for damaged or collapsed pipes, exhaust manifold for a collapsed inner wall, and mufflers for heat distress or possible internal failure.
19. Electromagnetic Interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI is present. If a problem exists, inspect routing of high voltage components, such as fuel injector wiring near the sensor circuits.
20. Inspect the Park/Neutral Position (PNP) switch circuit.
21. Inspect for a short to 5-volt circuit on one of the fuel injector control circuit between ECM and FICM.
22. Inspect for faulty motor mounts.
23. Inspect intake and exhaust manifold passages for casting flash.

Check for the following items

1. Ensure driver understands the Torque Converter Clutch (TCC) operation.
2. Ensure driver understands the A/C compressor operation.
3. Compare scan tool data at idle with scan tool data list. See «PID VALUE CHARTS»(ref-157358-S37375335102003081100000) in PID VALUE CHARTS - SILVERADO & SIERRA article.
4. Use scan tool to ensure the Vehicle Speed Sensor (VSS) reading matches the speedometer. This excludes vehicles with electronic transmissions where some variation between VSS and speedometer is normal.
5. Inspect Fuel Rail Pressure (FRP) sensor. Observe FRP with scan tool. The FRP should be between 1.1-1.4 MPa. If not, inspect for high resistance in the FRP sensor circuits or FRP sensor.
6. Test for an intermittent FRP sensor signal by wiggling harness between sensor and ECM with ignition on, and engine off, while monitoring the parameter with scan tool.
7. Observe FRP sensor and fuel pressure regulator commanded percent at idle. FRP should be near 40 MPa, and commanded percent should be near 40 percent. If command is high, a fuel pressure or sensor problem exists.
8. Inspect the Crankshaft Position (CKP) sensor reluctor wheel. Remove CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement, the reluctor wheel retaining bolts are loose.
9. Inspect fuel supply system pressure while the problem exists.
10. Check for a sticking fuel pressure regulator. The symptom for this condition will be an idle surge of at least 100 RPM. This surge will be from 50 RPM above or below desired idle speed. See «FUEL SYSTEM DIAGNOSIS - HIGH PRESSURE SIDE»(ref-152810-S21775685432003022800000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
11. Inspect the fuel injection control circuits between the ECM and Fuel Injection Control Module (FICM) for a short to a 5-volt reference circuit.
12. Inspect control module grounds for being clean, tight, and in their proper locations.
13. Inspect generator output voltage. Repair if voltage is less than 9 volts or more than 16 volts.
14. Inspect Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

RESTRICTED EXHAUST

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and diagnosis should begin there. To diagnose exhaust system, refer to EXHAUST SYSTEM BACKPRESSURE under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.

INTERMITTENTS

Note. Intermittent is a DTC or symptom, with a condition that cannot be duplicated.

PRELIMINARY

Perform the Diagnostic System Check - Engine Controls before starting. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.

CONTROL MODULE POWER & GROUNDS, & COMPONENT POWER & GROUNDS

Poor power or ground connections can cause widely varying symptoms.

1. Test all control module power circuits. Many vehicles have multiple circuits supplying power to the control module. Other components in the system may have separate power circuits that may also need to be tested. Inspect connections at the module or component connectors, fuses, and any intermediate connections between the power source and the module or component. A test light or a Digital Volt-Ohmmeter (DVOM) may indicate that voltage is present, but neither tests the ability of a circuit to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component. See POWER DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
2. Test all control module ground and system ground circuits. The control module may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested. Inspect grounds for clean and tight connections at the grounding point. Inspect the connections at the component and in splice packs, where applicable. Ensure that the circuit can carry the current necessary to operate the component. See GROUND DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

TEMPERATURE SENSITIVITY

1. An intermittent condition may occur when a component or connection reaches normal operating temperature. The condition may occur only when the component or connection is cold, or only when the connection is hot.
2. The following data may help to diagnose this type of intermittent condition: Freeze Frame/Failure Records. Scan tool snapshot. Vehicle data recorder.
3. If the intermittent is related to heat, review the following data: High ambient temperatures. Underhood or engine generated heat. Circuit generated heat due to a poor connection, or high electrical load. Higher than normal load conditions, such as towing.
4. If the intermittent is related to cold, review the following data: Low ambient temperatures. In extremely low temperatures, ice may form in a connection or component. Test for water intrusion. The condition only occurs on a cold start. The condition is not present after the vehicle warms up.
5. Information from the customer may help to determine if the trouble follows a pattern that is temperature related.

INCORRECT PCM PROGRAMMING

1. There are only a few situations when reprogramming a PCM is appropriate, such as the following: A new service PCM is installed. A PCM from another vehicle is installed. Revised software or calibration files have been released for this vehicle.
2. Verify that the PCM contains the correct software or calibration. If incorrect programming is found, reprogram the PCM with the most current software or calibration. See «ENGINE CONTROL MODULE»(ref-158516-S10218600282003100300000) under PROGRAMMING in SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.

DUPLICATING FAILURE CONDITIONS

1. If none of the previous tests are successful, attempt to duplicate or capture the failure conditions.
2. Freeze Frame/Failure Records data, where applicable, contains the conditions that were present when the DTC set. Perform the following procedure: Review and record Freeze Frame/Failure Records data. Clear DTCs using scan tool. Turn ignition off and wait 15 seconds. Operate vehicle under the same conditions that were noted in Freeze Frame/Failure Records data, as closely as possible. The vehicle must also be operating within the Conditions for Running DTC. Monitor DTC Status for the DTC being tested. The scan tool will indicate Ran, when the enabling conditions have been satisfied long enough for the DTC to run. The scan tool will also indicate whether the DTC passed or failed.
3. An alternate method is to drive vehicle with DVOM connected to a suspected circuit. An abnormal reading on the DVOM when problem occurs, may help you locate the problem.

VEHICLE DATA RECORDER

The Vehicle Data Recorder (J-42598) is connected to the Data Link Connector (DLC) and sent with customer. The vehicle data recorder captures data for later retrieval and analysis by the technician. Refer to vehicle data recorder user instructions for more information.