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Engine Controls - 4.8L, 5.3L, & 6.0L (Introduction): Diagnosis Chevrolet Silverado 3500

Testing & Diagnostics 4 illustrations ~1898 words

Action Taken When the DTC Sets - Type A

The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

Action Taken When the DTC Sets - Type B

The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.

Conditions for Clearing the MIL/DTC - Type A or Type B

  1. The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  2. A current DTC Last Test Failed clears when the diagnostic runs and passes.
  3. Use a scan tool in order to clear the MIL and the DTC.

Action Taken When the DTC Sets - Type C

  1. The control module stores the DTC information into memory when the diagnostic runs and fails.
  2. The MIL will not illuminate.
  3. The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC - Type C

  1. A last test failed, or current DTC, clears when the diagnostic runs and passes.
  2. Use a scan tool in order to clear the DTC.

Conditions for Clearing the DTC - Type X

This DTC is available in the PCM software, but has been disabled, or turned OFF. In this case, the diagnostic does not run, no DTCs are stored, and the MIL does not illuminate. Type X DTCs are used primarily for export vehicles that do not require MIL illumination or DTC storing.

Diagnostic Trouble Code (DTC) Type(s)

DTC CodeUnited States Canada RPO NC1, NF2, NF4, NT9Unleaded Export Light Duty (less than 8600 GVWR) RPO NF9Unleaded Export and all Heavy Duty (more than 8600 GVWR) RPO NC8, NF4, NT9, NF9
P0068AAA
P0101BBB
P0102BBB
P0103BBB
P0106BBB
P0107BBB
P0108BBB
P0112BBB
P0113BBB
P0116BBX
P0117BBB
P0118BBB
P0120AAA
P0125BBX
P0128BBX
P0131BBB
P0132BBB
P0133BBX
P0134BBB
P0135BBX
P0136BBB
P0137BBB
P0138BBB
P0140BBB
P0141BXX
P0151BBB
P0152BBB
P0153BBX
P0154BBB
P0155BBX
P0156BBB
P0157BBB
P0158BBB
P0160BBB
P0161BBX
P0169CCC
P0171BBB
P0172BBB
P0174BBB
P0175BBB
P0200BBB
P0218CCC
P0220AAA
P0230BBB
P0300BB (No MIL)B (No MIL)
P0315AAA
P0325BBB
P0327BBB
P0332BBB
P0335BBB
P0336BBB
P0341BBB
P0342BBB
P0343BBB
P0351BBB
P0352BBB
P0353BBB
P0354BBB
P0355BBB
P0356BBB
P0357BBB
P0358BBB
P0420AAX
P0430AAX
P0442AXX
P0443BBB
P0446AAX
P0449BBX
P0452BBX
P0453BBX
P0455AAX
P0461CCC
P0462CCC
P0463CCC
P0496BBX
P0500CCC
P0502BBC
P0503BBC
P0506BBB
P0507BBB
P0522CCC
P0523CCC
P0530CCC
P0562CCC
P0563CCC
P0567CCC
P0568CCC
P0571CCC
P0601AAA
P0602AAA
P0604AAA
P0606AAA
P0608CCC
P0609CCC
P0622CCC
P0641BBB
P0650B (No MIL)B (No MIL)B (No MIL)
P0651BBB
P0654CCC
P0706CCC
P0711CCC
P0712CCC
P0713CCC
P0716BBC
P0717BBC
P0719CCC
P0724CCC
P0730CCC
P0740BBX
P0741BBC
P0742BBC
P0748CCC
P0751BBC
P0752BBC
P0753BBC
P0756AAC
P0757AAC
P0758AAC
P0785BBX
P0833BBB
P0856CCC
P0894BCC
P1106CCC
P1107CCC
P1111CCC
P1112CCC
P1114CCC
P1115CCC
P1125AAA
P1133BBB
P1134BBB
P1153BBB
P1154BBB
P1172CCC
P1258AAA
P1380CCX
P1381CCX
P1516AAA
P1574CCC
P1626CCC
P1631CCC
P1637CCC
P1689CCC
P1810BBC
P2066CCC
P2067CCC
P2068CCC
P2101AAA
P2108AAA
P2120CCC
P2121CCC
P2125CCC
P2135AAA
P2610BBB
U0107AAA

Diagnostic Trouble Code (DTC) Type(s)

Scheme 40

Scheme 40: Emission Hose Routing Diagram
CalloutComponent Name
1Manifold Absolute Pressure (MAP) Sensor
2EVAP Canister Purge Hose
3EVAP Service Port
4Positive Crankcase Ventilation (PCV) Valve
5Throttle Body
6EVAP Canister Purge Valve
7AIR Module, if equipped

Scheme 41

Scheme 41: Evaporative Emissions (EVAP) Hose Routing Diagram
CalloutComponent Name
1EVAP Canister Purge Solenoid Valve
2EVAP Canister
3Fuel Fill Neck/Fill Cap
4Rollover Valve/Fuel Tank Pressure (FTP) Sensor
5Fuel Tank
6EVAP Canister Vent Solenoid Valve
7Vent Hose/Pipe
8EVAP Vapor Pipe
9EVAP Purge Pipe
10EVAP Service Port

Scheme 42

Scheme 42: Fuel Hose/Pipes Routing Diagram (Single Fuel Tank)
CalloutComponent Name
1Fuel Pressure Service Connection
2Fuel Injector Rail
3Fuel Rail Feed Pipe
4Fuel Feed Hose
5Fuel Injector

Inspection Procedure

IMPORTANTDo not perform this procedure unless instructed by an EVAP diagnostic.
  1. Turn OFF the ignition.
  2. Remove the EVAP canister purge valve. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(ref-184136-S20974252982005082200000) .
  3. Lightly tap the EVAP canister purge valve on a clean hard surface.
  4. Inspect for carbon particles exiting either of the vacuum ports. If no carbon particles are found reinstall the EVAP canister purge valve and continue with the EVAP cleaning procedure. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(ref-184136-S20974252982005082200000) . If carbon particles are found during the inspection procedure, replace the EVAP canister purge valve and continue with the EVAP cleaning procedure. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(ref-184136-S20974252982005082200000) . If you were instructed to replace the EVAP canister purge valve, and no carbon particles are found, return to the EVAP diagnostic procedure. Do not perform the EVAP cleaning procedure.

Spark Plug Wire Inspection

Spark plug wire integrity is vital for proper engine operation. A thorough inspection is necessary to accurately identify conditions that may affect engine operation. Inspect for the following conditions

  1. Correct routing of the spark plug wires-Incorrect routing may cause cross-firing.
  2. Any signs of cracks or splits in the wires.
  3. Inspect each boot for the following conditions: Tearing Piercing Arcing Carbon tracking Corroded terminal

If corrosion, carbon tracking or arcing are indicated on a spark plug wire boot or terminal, replace the wire and the component connected to the wire.

Spark Plug Inspection

  1. Verify that the correct spark plug is installed. An incorrect spark plug causes driveability conditions. Refer to «Ignition System Specifications»(ref-184136-S08279977642005082200000) for the correct spark plug.
  2. Ensure that the spark plug has the correct heat range. An incorrect heat range causes the following conditions: Spark plug fouling - Colder plug Pre-ignition causing spark plug and/or engine damage - Hotter plug
  3. Inspect the terminal post (1) for damage. Inspect for a bent or broken terminal post (1). Test for a loose terminal post (1) by twisting and pulling the post. The terminal post (1) should not move.
  4. Inspect the insulator (2) for flashover or carbon tracking, or soot. This is caused by the electrical charge traveling across the insulator (2) between the terminal post (1) and ground. Inspect for the following conditions: Inspect the spark plug boot for damage. Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A spark plug boot that is saturated will cause arcing to ground.
  5. Inspect the insulator (2) for cracks. All or part of the electrical charge may arc through the crack instead of the electrodes (3, 4).
  6. Inspect for evidence of improper arcing. Measure the gap between the center electrode (4) and the side electrode (3). Refer to «Ignition System Specifications»(ref-184136-S08279977642005082200000) . An excessively wide electrode gap can prevent correct spark plug operation. Inspect for the correct spark plug torque. Refer to «Ignition System Specifications»(ref-184136-S08279977642005082200000) . Insufficient torque can prevent correct spark plug operation. An over torqued spark plug, causes the insulator (2) to crack. Inspect for signs of tracking that occurred near the insulator tip instead of the center electrode (4). Inspect for a broken or worn side electrode (3). Inspect for a broken, worn, or loose center electrode (4) by shaking the spark plug. A rattling sound indicates internal damage. A loose center electrode (4) reduces the spark intensity. Inspect for bridged electrodes (3, 4). Deposits on the electrodes (3, 4) reduce or eliminates the gap. Inspect for worn or missing platinum pads on the electrodes (3, 4), if equipped. Inspect for excessive fouling.
  7. Inspect the spark plug recess area of the cylinder head for debris. Dirty or damaged threads can cause the spark plug not to seat correctly during installation.

Visual Inspection

  1. Normal operation - Brown to grayish-tan with small amounts of white powdery deposits are normal combustion by-products from fuels with additives.
  2. Carbon fouled - Dry, fluffy black carbon, or soot caused by the following conditions: Rich fuel mixtures Leaking fuel injectors Excessive fuel pressure Restricted air filter element Incorrect combustion Reduced ignition system voltage output Weak ignition coils Worn ignition wires Incorrect spark plug gap Excessive idling or slow speeds under light loads can keep spark plug temperatures so low that normal combustion deposits may not burn off.
  3. Deposit fouling - Oil, coolant, or additives that include substances such as silicone, very white coating, reduces the spark plug intensity. Most powdery deposits will not affect spark plug intensity unless they form into a glazing over the electrode.

Scheme 43

Scheme 43: Removal Procedure
  1. Remove the spark plug wire. Refer to «Spark Plug Wire Replacement»(ref-184136-S22902163132005082200000) .
  2. Loosen the spark plug 1 or 2 turns.
  3. Brush or using compressed air, blow away any dirt from around the spark plug.
  4. Remove the spark plug. If removing more than one plug, place each plug in a tray marked with the corresponding cylinder number.

Diagnostic Trouble Codes (DTCs)

The powertrain control module (PCM) is programmed with test routines that test the operation of the various systems the PCM controls. Some tests monitor internal PCM functions. Many tests are run continuously. Other tests run only under specific conditions, referred to as Conditions for Running the DTC. When the vehicle is operating within the conditions for running a particular test, the PCM monitors certain parameters and determines if the values are within an expected range. The parameters and values considered outside the range of normal operation are listed as Conditions for Setting the DTC. When the Conditions for Setting the DTC occur, the PCM executes the Action Taken When the DTC Sets. Some DTCs alert the driver via the malfunction indicator lamp (MIL) or a message. Other DTCs do not trigger a driver warning, but are stored in memory. The PCM also saves data and input parameters when most DTCs are set. This data is stored in the Freeze Frame and/or Failure Records.

The DTCs are categorized by type. The DTC type is determined by the MIL operation and the manner in which the fault data is stored when a particular DTC fails. In some cases there may be exceptions to this structure. Therefore, when diagnosing the system it is important to read the Action Taken When the DTC Sets and the Conditions for Clearing the DTC in the supporting text.

There are different types of DTCs and different actions taken when the DTCs set. Refer to Diagnostic Trouble Code (DTC) Type Definitions for a description of the general characteristics of each DTC type.

DTC Status

When the scan tool displays a DTC, the status of the DTC is also displayed. The following DTC statuses are indicated only when they apply to the DTC that is set.

Large Leak Test

This tests for large leaks and blockages in the evaporative emission (EVAP) system. The control module commands the EVAP vent solenoid valve ON and commands the EVAP purge solenoid valve ON, with the engine running, allowing engine vacuum into the EVAP system. The control module monitors the fuel tank pressure (FTP) sensor voltage to verify that the system is able to reach a predetermined level of vacuum within a set amount of time. The control module then commands the EVAP purge solenoid valve OFF, sealing the system, and monitors the vacuum level for decay. If the control module does not detect that the predetermined vacuum level was achieved, or the vacuum decay rate is more than a calibrated level on 2 consecutive tests, DTC P0455 will set.

Small Leak Test

The engine off natural vacuum (EONV) diagnostic is the small-leak detection diagnostic for the evaporative emission (EVAP) system. While previous leak detection methods were performed with the engine running, the EONV diagnostic monitors the EVAP system pressure or vacuum with the ignition OFF. Because of this, it may be normal for the control module to remain active for up to 40 minutes after the ignition is turned OFF. This is important to remember when performing a parasitic draw test on vehicles equipped with EONV.

The EONV utilizes the temperature changes in the fuel tank immediately following a drive cycle to use the naturally occurring vacuum or pressure in the fuel tank. When the vehicle is driven, the temperature rises in the tank. After the vehicle is parked, the temperature in the tank continues to rise for a period of time, then starts to drop. The EONV diagnostic relies on this temperature change and the corresponding pressure change in a sealed system, to determine if an EVAP system leak is present.

The EONV diagnostic is designed to detect leaks as small as 0.51 mm (0.020 in). The diagnostic can determine if a small leak is present based on vacuum or pressure readings in the EVAP system. When the system is sealed, a finite amount of pressure or vacuum will be observed. When a 0.51 mm (0.020 in) leak is present, often little or no pressure or vacuum is observed. If the test reports a failing value, DTC P0442 will set.

Canister Vent Restriction Test

If the evaporative emission (EVAP) vent system is restricted, fuel vapors will not be properly purged from the EVAP canister. The control module tests this by commanding the EVAP purge solenoid valve ON, commanding the EVAP vent solenoid valve OFF, and monitoring the fuel tank pressure (FTP) sensor for an increase in vacuum. If the vacuum increases more than a calibrated value, DTC P0446 will set.

Purge Solenoid Valve Leak Test

If the evaporative emission (EVAP) purge solenoid valve does not seal properly fuel vapors could enter the engine at an undesired time, causing driveability concerns. The control module tests for this by commanding the EVAP purge solenoid valve OFF and the vent solenoid valve ON, sealing the system, and monitors the fuel tank pressure (FTP) for an increase in vacuum. If the control module detects that the EVAP system vacuum increases above a calibrated value, DTC P0496 will set.