Engine Controls - 8.1l (Introduction) Chevrolet Cab & Chassis Silverado 3500

Temperature vs Resistance

Temperature vs Resistance

Altitude vs Barometric Pressure

Altitude vs Barometric Pressure

Ignition System Specifications

Ignition System Specifications

Fastener Tightening Specifications

Fastener Tightening Specifications

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.

Non-Emissions Related DTCs

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)

Diagnostic Trouble Code (DTC) Type(s)

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Scheme 146

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Engine Controls Schematic Icons

Engine Controls Schematic Icons Icon Icon Definition NOTE: The OBD II symbol is used on the circuit diagrams in order to alert the technician that the circuit is essential for proper OBD II emission control circuit operation. Any circuit which fails and causes the malfunction indicator lamp (MIL) to turn ON, or causes emissions-related component damage, is identified as an OBD II circuit

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Scheme 172

Powertrain Control Module (PCM) Connector End Views

Powertrain Control Module (PCM) - C1 Connector Part Information 12191489 80-Way F Micro-Pack 100W Sealed (BU) Pin Wire Color Circuit No. Function 1 BK/WH 451 Ground 2 L-GN 1867 12-Volt Reference 3 PK/BK 1746 Fuel Injector 3 Control 4 L-GN/BK 1745 Fuel Injector 2 Control 5-6 - - Not Used 7 GY 2705 5-Volt Reference 8-10 - - Not Used 11 L-BU 1876 Knock Sensor 2 Signal 12 D-BU/ WH 1869 CKP Sensor Signal 13 OG/BK 463 Requested Torque Signal (M74) 14 OG/BK 1061 UART Serial Data 15 D-BU/ WH 774 UART Serial Data 16-18 - - Not Used 19 PK 439 Ignition 1 Voltage 20 OG 440 Battery Positive Voltage 21 YE/BK 1868 Low Reference 22 L-GN 488 PTO on Switch Signal (PTO) 23 BK 470 Low Reference 24 BK/WH 451 Ground (NC1) 25 TN 1671 HO2S Low Signal Bank 2 Sensor 2 (NC1) 26 TN 1667 HO2S Low Signal Bank 2 Sensor 1 27 BK/WH 451 Ground (NC1) 28 TN 1669 HO2S Low Signal Bank 1 Sensor 2 (w/NC1) 29 TN/WH 1664 HO2S Low Signal Bank 1 Sensor 1 30 L-GN 1478 Coolant Level Switch Signal 31-32 - - Not Used 33 PU 420 TCC Brake Switch/Cruise Control Release Signal 34 OG/BK 1786 Park/Neutral Signal (M74) 35 GY 48 CPP Switch Signal (ML6) 36 BK 1744 Fuel Injector 1 Control 37 YE/BK 846 Fuel Injector 6 Control 38 - - Not Used 39 YE/BK 625 Starter Enable Relay Control 40 BK/WH 451 Ground 41-42 - - Not Used 43 RD/BK 877 Fuel Injector 7 Control 44 L-BU/BK 844 Fuel Injector 4 Control 45 GY 2700 5-Volt Reference 46 GY 474 5-Volt Reference 47 - - Not Used 48 GY 597 5-Volt Reference 49-50 - - Not Used 51 D-BU 496 Knock Sensor 1 Signal 52 YE 2522 PTO Engage Signal (PTO) 53 - - Not Used 54 OG/BK 469 Low Reference 55 - - Not Used 56 - - Not Used 57 OG 440 Battery Positive Voltage 58 D-GN 1049 Class 2 Serial Data 59-60 - - Not Used 61 PK/BK 632 Low Reference 62 - - Not Used 63 BK 2755 Low Reference 64 BK/WH 451 Ground 65 PU 1670 HO2S High Signal Bank 2 Sensor 2 (NC1) 66 PU 1666 HO2S High Signal Bank 2 Sensor 1 67 BK/WH 451 Ground 68 PU/WH 1668 HO2S High Signal Bank 1 Sensor 2 (NC1) 69 PU/WH 1665 HO2S High Signal Bank 1 Sensor 1 70 BN 1174 Oil Level Switch Signal 71 L-BU 494 Engine Shut Off Signal (PTO) 72 - - Not Used 73 BN/WH 633 CMP Sensor Signal 74 YE 410 ECT Sensor Signal 75 PK 1020 Ignition 0 Voltage 76 BK/WH 845 Fuel Injector 5 Control 77 D-BU/ WH 878 Fuel Injector 8 Control 78 PU 2562 PTO Control (PTO) 79 - - Not Used 80 GY 720 Low Reference

Powertrain Control Module (PCM) - C2 Connector Part Information 12191488 80-Way F Micro-Pack 100W Sealed (RD) Pin Wire Color Circuit No. Function 1 BK/WH 451 Ground 2 WH 2467 Throttle Kickdown Signal (M74) 3 TN 1465 Fuel Pump Relay Control - Secondary 4 - - Not Used 5 TN/BK 464 Delivered Torque Signal (M74) 6-8 - - Not Used 9 D-GN/ WH 465 Fuel Pump Relay Control 10 WH 121 Engine Speed Signal 11 - - Not Used 12 D-BU 2466 Trans MIL Request Signal (M74) 13 - - Not Used 14 RD/BK 380 A/C Refrigerant Pressure Sensor Signal 15 BN 25 Charge Indicator Control 16 GY/BK 1694 4WD Low Signal (NP1/NP2) 17 - - Not Used 18 D-GN 1433 Clutch Start Switch Signal (ML6) 19 BK/WH 1695 Axle Switch Signal (NP2) 20 L-GN/BK 822 VSS Low Signal 21 PU/WH 821 VSS High Signal (ML6) YE 400 Signal High - Front (M74) 22-24 - - Not Used 25 TN 472 IAT Sensor Signal 26 PU 2121 IC 1 Control 27 RD 2127 IC 7 Control 28 L-BU/WH 2126 IC 6 Control 29 D-GN/ WH 2124 IC 4 Control 30 - - Not Used 31 YE 492 MAF Sensor Signal 32 L-GN 432 MAP Sensor Signal 33 - - Not Used 34 D-GN/ WH 428 EVAP Canister Purge Solenoid Control 35-38 - - Not Used 39 RD 631 12-Volt Reference 40 BK/WH 451 Ground 41-42 - - Not Used 43 D-GN/ WH 459 A/C Compressor Clutch Relay Control 44 - - Not Used 45 WH 1310 EVAP Canister Vent Solenoid Control 46 BN/WH 419 MIL Control 47-48 - - Not Used 49 YE/BK 1827 Vehicle Speed Signal 50 D-GN/ WH 817 Vehicle Speed Signal 51 - - Not Used 52 BN 2391 HO2S Heater Low Control Bank 1 Sensor 2 (NC1) 53 RD/WH 3223 HO2S Heater Low Control Bank 2 Sensor 2 (NC1) 54 PU 1589 Fuel Level Sensor Signal 55-56 - - Not Used 57 BK 552 Low Reference 58 TN/WH 332 Oil Pressure Sensor Signal 59 PU 806 Crank Voltage 60 BN 2129 Low Reference 61 BN/WH 2130 Low Reference 62-63 - - Not Used 64 D-GN 890 Fuel Tank Pressure Sensor Signal 65 - - Not Used 66 PU/WH 2128 IC 8 Control 67 RD/WH 2122 IC 2 Control 68 D-GN 2125 IC 5 Control 69 L-BU 2123 IC 3 Control 70-71 - - Not Used 72 BK/WH 3113 HO2S Heater Low Control Bank 1 Sensor 2 (NC1) 73 D-BU 1936 Fuel Level Sensor Signal - Secondary 74 L-GN 3212 HO2S Heater Low Control Bank 2 Sensor 1 75 GY 23 Generator Field Duty Cycle Signal 76-79 - - Not Used 80 BK 2751 Low Reference

Engine Controls Connector End Views

Accelerator Pedal Position (APP) Sensor Connector Part Information 15318071 10-Way F Metri-Pack 150 Series (GY) Pin Wire Color Circuit No. Function A - - Not Used B PU 1272 5-Volt Reference C L-BU 1162 APP Sensor 2 Signal D TN 1274 Low Reference E BN 1271 Low Reference F D-BU 1161 APP Sensor 1 Signal G WH/BK 1164 5-Volt Reference H - - Not Used J-K - - Not Used

Camshaft Position (CMP) Sensor Connector Part Information 12059595 3-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A RD 631 12-Volt Reference B PK/BK 632 Low Reference C BN/WH 633 CMP Sensor Signal

Crankshaft Position (CKP) Sensor Connector Part Information 15324165 3-Way F Metri-Pack 150 Series (NA) Pin Wire Color Circuit No. Function A L-GN 1867 12-Volt Reference B YE/BK 1868 Low Reference C D-BU/WH 1869 CKP Sensor Signal

Engine Coolant Temperature (ECT) Sensor Connector Part Information 15324589 3-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A BK 407 Low Reference B YE 410 ECT Sensor Signal C - - Not Used

Evaporative Emission (EVAP) Canister Purge Solenoid Connector Part Information 12052643 2-Way F Metri-Pack 150 Series Sealed (RD) Pin Wire Color Circuit No. Function A PK 439 Ignition 1 Voltage B D-GN/WH 428 EVAP Canister Purge Solenoid Control

Evaporative Emission (EVAP) Canister Vent Solenoid Connector Part Information 12052643 2-Way F Metri-Pack 150 Series Sealed (RD) Pin Wire Color Circuit No. Function A WH 1310 EVAP Canister Vent Solenoid Control B PK 2640 Battery Positive Voltage

Fuel Injector 1 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK/WH 1039 Ignition 1 Voltage B BK 1744 Fuel Injector 1 Control

Fuel Injector 2 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK 1239 Ignition 1 Voltage B L-GN/BK 1745 Fuel Injector 2 Control

Fuel Injector 3 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK/WH 1039 Ignition 1 Voltage B PK/BK 1746 Fuel Injector 3 Control

Fuel Injector 4 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK 1239 Ignition 1 Voltage B L-BU/BK 844 Fuel Injector 4 Control

Fuel Injector 5 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK/WH 1039 Ignition 1 Voltage B BK/WH 845 Fuel Injector 5 Control

Fuel Injector 6 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK 1239 Ignition 1 Voltage B YE/BK 846 Fuel Injector 6 Control

Fuel Injector 7 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK/WH 1039 Ignition 1 Voltage B RD/BK 877 Fuel Injector 7 Control

Fuel Injector 8 Connector Part Information 15411634 2-Way F Metri-Pack 280.1 P2S (BK) Pin Wire Color Circuit No. Function A PK 1239 Ignition 1 Voltage B D-BU/WH 878 Fuel Injector 8 Control

Fuel Pump (FP) Relay - Secondary (Dual Tanks) Connector Part Information 12129716 4-Way F Metri-Pack 280 FLX LK (MD GY) Pin Wire Color Circuit No. Function 30 PK 139 Ignition 1 Voltage 85 GY 120 Fuel Pump Supply Voltage 86 TN 1465 Fuel Pump Relay Control - Secondary 87 L-GN 1058 Fuel Balance Pump Supply Voltage

Fuel Pump and Sender Assembly - Primary Connector Part Information 15326631 4-Way F GT 280 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 2150 Ground B BK 470 Low Reference C PU 1589 Fuel Level Sensor Signal - Primary D GY 120 Fuel Pump Supply Voltage

Fuel Pump and Sender Assembly - Secondary (Dual Tanks) Connector Part Information 15326631 4-Way F GT 280 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 2150 Ground B BK 470 Low Reference C D-BU 1936 Fuel Level Sensor Signal D L-GN 1058 Fuel Balance Pump Supply Voltage

Fuel Tank Pressure (FTP) Sensor Connector Part Information 12059595 3-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 470 Low Reference B D-GN 890 Fuel Tank Pressure Sensor Signal C GY 474 5-Volt Reference

Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1 Connector Part Information 12092839 4-Way M Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A TN 1664 HO2S Low Signal Bank 1 Sensor 1 B PU/WH 1665 HO2S High Signal Bank 1 Sensor 1 C - - Not Available D PK 539 Ignition 1 Voltage E BK/WH 3113 HO2S Heater Low Control Bank 1 Sensor 1

Heated Oxygen Sensor (HO2S) Bank 1 Sensor 2 (NC1) Connector Part Information 12146047 4-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function A TN/WH 1669 HO2S Low Signal Bank 1 Sensor 2 B PU/WH 1668 HO2S High Signal Bank 1 Sensor 2 C - - Not Available D PK 1539 Ignition 1 Voltage E BN 2391 HO2S Heater Low Control Bank 1 Sensor 2

Heated Oxygen Sensor (HO2S) Bank 2 Sensor 1 Connector Part Information 12092839 4-Way M Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A TN 1667 HO2S Low Signal Bank 2 Sensor 1 B PU 1666 HO2S High Signal Bank 2 Sensor 1 C - - Not Available D PK 539 Ignition 1 Voltage E L-GN 3212 HO2S Heater Low Control Bank 2 Sensor 1

Heated Oxygen Sensor (HO2S) Bank 2 Sensor 2 (NC1) Connector Part Information 12092839 4-Way M Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A TN 1671 HO2S Low Signal Bank 2 Sensor 2 B PU 1670 HO2S High Signal Bank 2 Sensor 2 C - - Not Available D PK 1539 Ignition 1 Voltage E RD/WH 3223 HO2S Heater Low Control Bank 2 Sensor 2

Ignition Coil 1 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2129 Low Reference C PU 2121 IC 1 Control D PK 1039 Ignition 1 Voltage

Ignition Coil 2 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2130 Low Reference C RD 2122 IC 2 Control D PK 1239 Ignition 1 Voltage

Ignition Coil 3 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2129 Low Reference C L-BU 2123 IC 3 Control D PK 1039 Ignition 1 Voltage

Ignition Coil 4 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2130 Low Reference C D-GN 2124 IC 4 Control D PK 1239 Ignition 1 Voltage

Ignition Coil 5 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2129 Low Reference C D-GN 2125 IC 5 Control D PK 1039 Ignition 1 Voltage

Ignition Coil 6 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2130 Low Reference C L-BU 2126 IC 6 Control D PK 1239 Ignition 1 Voltage

Ignition Coil 7 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2129 Low Reference C RD 2127 IC 7 Control D PK 1039 Ignition 1 Voltage

Ignition Coil 8 Connector Part Information 15366040 4-Way F Metri-Pack 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A BK 550 Ground B BN 2130 Low Reference C PU 2128 IC 8 Control D PK 1239 Ignition 1 Voltage

Knock Sensor (KS) - Bank 1 Connector Part Information 15355362 1-Way F Metri-Pack 150 Series Sealed (NA) Pin Wire Color Circuit No. Function 1 D-BU 496 Knock Sensor - 1 Signal

Knock Sensor (KS) - Bank 2 Connector Part Information 15355362 1-Way F Metri-Pack 150 Series Sealed (NA) Pin Wire Color Circuit No. Function 1 L-BU 1876 Knock Sensor - 2 Signal

Mass Air Flow (MAF) Sensor/Intake Air Temperature (IAT) Connector Part Information 15305555 5-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function A BK 552 Low Reference B TN 472 IAT Sensor Signal C BK/WH 451 Ground D PK 439 Ignition 1 Voltage E YE 492 MAF Sensor Signal

Manifold Absolute Pressure (MAP) Sensor Connector Part Information 12129946 3-Way F Metri-Pack 150 Series Sealed (GY) Pin Wire Color Circuit No. Function A OG/BK 469 Low Reference B L-GN 432 MAP Sensor Signal C GY 597 5-Volt Reference

Throttle Actuator Control (TAC) Module - C1 Connector Part Information 12191068 16-Way F Micro-Pack 100 Series (GY) Pin Wire Color Circuit No. Function 1 D-GN 485 TP Sensor 1 Signal 2 GY 416 5-Volt Reference 3 BK 452 Low Reference 4 D-BU 84 Cruise Control Set/Coast Switch Signal 5 GY/BK 87 Cruise Control Resume/Accel Switch Signal 6 L-BU 1320 CHMSL Supply Voltage 7 PK 1339 Ignition 1 Voltage 8 BN 582 TAC Motor Control - 2 9 L-BU/BK 1688 5-Volt Reference 10 BK/WH 1704 Low Reference 11 PU 486 TP Sensor 2 Signal 12 OG/BK 1061 UART Serial Data 13 D-BU/WH 774 UART Serial Data 14 GY 397 Cruise Control On Switch Signal 15 BK/WH 550 Ground 16 YE 581 TAC Motor Control - 1

Throttle Actuator Control (TAC) Module - C2 Connector Part Information 12177081 10-Way F 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A - - Not Used B PU 1272 5-Volt Reference C L-BU 1162 APP Sensor 2 Signal D TN 1274 Low Reference E - - Not Used F D-BU 1161 APP Sensor 1 Signal G WH/BK 1164 5-Volt Reference H-J - - Not Used

Throttle Body Connector Part Information 15326836 8-Way F GT 150 Series (BK) Pin Wire Color Circuit No. Function A YE 581 TAC Motor Control - 1 B BK/WH 1704 Low Reference C BN 582 TAC Motor Control - 2 D BK 452 Low Reference E L-BU/BK 1688 5-Volt Reference F PU 486 TP Sensor 2 Signal G D-GN 485 TP Sensor 1 Signal H GY 416 5-Volt Reference

Powertrain Control Module (PCM) Replacement

Service of the powertrain control module (PCM) should consist of either replacement of the PCM or programming of the electrically erasable programmable read only memory (EEPROM). If the diagnostic procedures call for the PCM to be replaced, the replacement PCM should be checked to ensure that the correct part is being used. If the correct part is being used, remove the faulty PCM and install the new service PCM.

Removal Procedure

1. Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.
2. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
3. If equipped with the Allison transmission regular production option (RPO) M74, remove the engine harness clip from the PCM cover.
4. Release the PCM cover mounting tabs.
5. Release the PCM cover from the mounting bracket.
6. Remove the PCM cover.
7. Loosen the PCM electrical connector bolts (2).
8. Disconnect the PCM electrical connectors.
9. Release the spring latch from the PCM.
10. Release the PCM mounting tabs from the PCM.
11. Remove the PCM.

Installation Procedure

1. Install the PCM. Ensure that the mounting tabs are engaged.
2. Secure the spring latch to the PCM.
3. Connect the PCM electrical connectors.
4. Tighten the PCM electrical connector bolts (2). Tighten: Tighten the bolts to 8 N.m (71 lb in).
5. Install the PCM cover.
6. If equipped with the Allison transmission RPO M74, install the engine harness clip to the PCM cover.
7. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
8. If a NEW PCM was installed, program the PCM. Refer to «Control Module References»(ref-197326-S18267990112005101100000) in Computer/Integrating Systems.

1. Remove the connector position assurance (CPA) retainer (1).
2. Disconnect the instrument panel (I/P) harness electrical connector (2).
3. Disconnect the engine wiring harness electrical connector (1).
4. Remove the throttle actuator control (TAC) module nuts.
5. Remove the TAC module.
6. If equipped with a regular production option (RPO) ML6 manual transmission, unsnap the TAC module from the bracket.
7. If equipped with a RPO ML6 manual transmission, remove the TAC module bracket nuts.
8. Remove the TAC module bracket, if necessary.

1. If equipped with a RPO ML6 manual transmission, install the TAC module bracket, if necessary.
2. Install the TAC module bracket nuts. Tighten: Tighten the nuts to 9 N.m (80 lb in).
3. If equipped with a RPO ML6 manual transmission, snap the TAC module to the bracket.
4. Install the TAC module.
5. Install the TAC module nuts. Tighten: Tighten the nuts to 9 N.m (80 lb in).
6. Connect the engine wiring harness electrical connector (1).
7. Connect the I/P harness electrical connector (2).
8. Install the CPA retainer (1).

CKP System Variation Learn Procedure

1. Install a scan tool.
2. Monitor the powertrain control module (PCM) for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-197324-S09956880762005101100000) in Vehicle DTC Information for the applicable DTC.
3. Select the crankshaft position variation learn procedure with a scan tool.
4. The scan tool instructs you to perform the following: Accelerate to wide open throttle (WOT). Release throttle when fuel cut-off occurs. Observe fuel cut-off for applicable engine. Engine should not accelerate beyond calibrated RPM value. Release throttle immediately if value is exceeded. Block drive wheels. Set parking brake. DO NOT apply brake pedal. Cycle ignition from OFF to ON. Apply and hold brake pedal. Start and idle engine. Turn the A/C OFF. Vehicle must remain in Park or Neutral. The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components: Crankshaft position (CKP) sensors activity-If there is a CKP sensor condition, refer to the applicable DTC. Camshaft position (CMP) signal activity-If there is a CMP signal condition, refer to the applicable DTC. Engine coolant temperature (ECT)-If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
5. Enable the CKP system variation learn procedure with the scan tool.
6. Accelerate to WOT.
7. Release throttle when fuel cut-off occurs.
8. The scan tool display reads Test In Progress.
9. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to «DTC P0315»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-dtc-p0200-to-p0507) . If any other DTCs set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-197324-S09956880762005101100000) in Vehicle DTC Information for the applicable DTC.
10. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.
11. The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether or not DTC P0315 is set: An engine replacement A PCM replacement A harmonic balancer replacement A crankshaft replacement A CKP sensor replacement Any engine repairs which disturb the crankshaft to CKP sensor relationship.

Note. Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.

1. Drain the cooling system to a level below the engine coolant temperature (ECT) sensor. Refer to «Draining and Filling Cooling System (w/RPO HP2)»(ref-197356-S32653343972005101100000) or «Draining and Filling Cooling System (w/o RPO HP2)»(ref-197356-S16321664992005101100000) in Engine Cooling.
2. Disconnect the ECT sensor electrical connector (3).
3. Remove the ECT sensor electrical connector from the oil fill tube bracket.
4. Remove the ECT sensor.

1. If installing the old sensor, coat the threads with sealant GM P/N 12346004 (Canadian P/N 10953480) or equivalent.
2. Install the ECT sensor. Tighten: Tighten the sensor to 50 N.m (37 lb ft).
3. Install the ECT sensor electrical connector to the oil fill tube bracket.
4. Connect the ECT sensor electrical connector (3).
5. Refill the cooling system. Refer to «Draining and Filling Cooling System (w/RPO HP2)»(ref-197356-S32653343972005101100000) or «Draining and Filling Cooling System (w/o RPO HP2)»(ref-197356-S16321664992005101100000) in Engine Cooling.

1. Remove the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the MAF/IAT sensor electrical connector (3).
3. Loosen the MAF/IAT clamp.
4. Remove the MAF/IAT sensor from the air cleaner assembly.

1. Locate the air flow direction arrow (2) on the MAF/IAT sensor.
2. Install the MAF/IAT sensor to the air cleaner assembly.
3. Tighten the MAF/IAT clamp. Tighten: Tighten the clamp to 7 N.m (62 lb in).
4. Connect the MAF/IAT sensor electrical connector (3).
5. Install the air intake resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Remove the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
2. Disconnect the manifold absolute pressure (MAP) sensor electrical connector (1).
3. Remove the MAP sensor bolt.
4. Remove the MAP sensor.
5. Inspect the MAP sensor seal for wear or damage, replace as necessary.

1. Install the MAP sensor.
2. Install the MAP sensor bolt. Tighten: Tighten the bolt to 12 N.m (106 lb in).
3. Connect the MAP sensor electrical connector (1).
4. Install the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.

Note. Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Disconnect the connector position assurance (CPA) retainer.
3. Disconnect the heated oxygen sensor (HO2S) electrical connector (1).
4. Remove the HO2S (1).

1. If reinstalling the old sensor, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.
2. Install the HO2S (1). Tighten: Tighten the sensor 42 N.m (31 lb ft).
3. Connect the HO2S electrical connector (1).
4. Connect the CPA retainer.
5. Lower the vehicle.

Note. Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Disconnect the connector position assurance (CPA) retainer.
3. Disconnect the heated oxygen sensor (HO2S) electrical connector (1).
4. Remove the HO2S (3).

1. If reinstalling the old sensor, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.
2. Install the HO2S (3). Tighten: Tighten the sensor to 42 N.m (31 lb ft).
3. Connect the HO2S electrical connector (1).
4. Connect the CPA retainer.
5. Lower the vehicle.

Note. Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Disconnect the connector position assurance (CPA) retainer.
3. Disconnect the heated oxygen sensor (HO2S) electrical connector.
4. Remove the HO2S (3).

1. If reinstalling the old sensor, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.
2. Install the HO2S (3). Tighten: Tighten the sensor to 42 N.m (31 lb ft).
3. Connect the HO2S electrical connector.
4. Connect the CPA retainer.
5. Lower the vehicle.

Note. Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Disconnect the connector position assurance (CPA) retainer.
3. Disconnect the heated oxygen sensor (HO2S) electrical connector.
4. Remove the HO2S (2).

1. If reinstalling the old sensor, coat the threads with anti-seize compound GM P/N 12377953, or equivalent.
2. Install the HO2S (2). Tighten: Tighten the sensor to 42 N.m (31 lb ft).
3. Connect the HO2S electrical connector.
4. Connect the CPA retainer.
5. Lower the vehicle.

1. Remove the connector position assurance (CPA) retainer.
2. Disconnect the accelerator pedal position (APP) sensor electrical connector.
3. Reposition the carpet to access the lower nut.
4. Remove the accelerator pedal nuts.
5. Remove the accelerator pedal assembly.

1. Install the accelerator pedal assembly.
2. Install the accelerator pedal nuts. Tighten: Tighten the nuts to 20 N.m (15 lb ft).
3. Reposition the carpet.
4. Connect the APP sensor electrical connector.
5. Install the CPA retainer.
6. Reposition the carpet.
7. Connect a scan tool in order to test for proper throttle-opening and throttle-closing range.
8. Operate the accelerator pedal and monitor the throttle angles. The accelerator pedal should operate freely, without binding, between a closed throttle, and a wide open throttle (WOT).
9. Verify that the vehicle meets the following conditions: The vehicle is not in a reduced engine power mode. The ignition is ON. The ignition is OFF.
10. Inspect the carpet fit under the accelerator pedal.

Note. Handle the electronic throttle control components carefully. Use cleanliness in order to prevent damage. Do not drop the electronic throttle control components. Do not roughly handle the electronic throttle control components. Do not immerse the electronic throttle control components in cleaning solvents of any type.

1. Remove the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the throttle actuator motor electrical connector (5).
3. Remove the throttle body nuts.
4. Remove the throttle body.
5. Remove and discard the throttle body gasket.

1. Install a NEW throttle body gasket.
2. Install the throttle body. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
3. Install the throttle body nuts. Tighten: Tighten the nuts to 10 N.m (89 lb in).
4. Connect the throttle actuator motor electrical connector (5).
5. Install the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
6. Connect a scan tool in order to test for proper throttle-opening and throttle-closing range.
7. Operate the accelerator pedal and monitor the throttle angles. The accelerator pedal should operate freely, without binding, between a closed throttle, and a wide open throttle (WOT).
8. Verify that the vehicle meets the following conditions: The vehicle is not in a reduced engine power mode. The ignition is ON. The ignition is OFF.

Throttle Body Cleaning Procedure

1. Remove the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Inspect the throttle body bore and the throttle body plate for deposits. You will need to open the throttle plate in order to inspect all surfaces.
3. Clean the throttle body bore and the throttle plate using a clean shop towel with GM top engine cleaner, P/N 1052626 or AC Delco Carburetor Tune-up Conditioner, P/N X66P, or equivalent product.
4. Install the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

Tools Required

J 34730-1A Fuel Pressure Gage

1. Disconnect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
2. Install the J 34730-1A . Refer to «Fuel Pressure Gage Installation and Removal»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
3. Loosen the fuel fill cap in order to relieve fuel tank vapor pressure.
4. Open the valve on the J 34730-1A in order to bleed the system pressure. The fuel connections are now safe for servicing.
5. Drain any fuel remaining in the gage into an approved container.
6. Once the system pressure is completely relieved, remove the J 34730-1A . Refer to «Fuel Pressure Gage Installation and Removal»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

J 34730-1A Fuel Pressure Gage

1. Remove the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
2. Remove the fuel rail pressure cap.
3. Connect the J 34730-1A to the fuel pressure valve. Wrap a shop towel around the fitting while connecting the gage in order to avoid spillage.
4. Install the bleed hose on J 34730-1A into an approved container.

1. Remove the bleed hose on the J 34730-1A from the approved container.
2. Remove the shop towel from around the fitting and discard into an approved container.
3. Disconnect the J 34730-1A from the fuel pressure valve.
4. Install the fuel rail pressure fitting cap.
5. Install the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.

Quick Connect Fitting(s) Service (Metal Collar)

Tools Required

1. J 41769 Fuel Line Quick Disconnect Tool
2. J 43178 Fuel Line Disconnect Tool

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Remove the retainer from the fuel feed line to engine quick-connect fitting.
3. If equipped with the 5.3L (L59) engine, remove the retainers from the fuel feed and return line to engine quick-connect fittings.
4. Using compressed air, blow any dirt or debris from around the fitting.
5. Using the correct tool from J 41769 , insert the tool into the female connector, then push inward in order to release the quick connect locking tabs.
6. If the vehicle is a cab/chassis, it may be necessary to use J 43178 in order to release the quick connect locking tabs.
7. Pull the fuel line connection apart.
8. Use a clean shop towel in order to wipe off the male connection end.
9. Inspect both ends of the fitting for dirt and burrs. Clean or replace the components as required.

1. Apply a few drops of clean engine oil to the male connection end.
2. Push both sides of the fittings together in order to snap the retaining tabs into place.
3. Once installed, pull on both sides of the connection in order to make sure the connection is secure.
4. If equipped with the 5.3L (L59) engine, install the retainers to the fuel feed and return line to engine quick-connect fittings.
5. Install the retainer to the fuel feed line quick-connect fitting.
6. Install the fuel fill cap.
7. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
2. Using compressed air, blow any dirt or debris from around the quick connect fitting.
3. Squeeze the plastic quick connect fitting release tabs together to disengage the quick connect fitting. (This step applies to Bartholomew style fittings ONLY)
4. Squeeze where indicated by the arrows on both sides of the plastic ring to disengage the quick connect fitting.
5. Squeeze where indicated by the arrows on both sides of the plastic ring to disengage the quick connect fitting.
6. Pull the quick connect fitting connection apart.

1. Apply a few drops of clean engine oil to the male connection end.
2. Push both sides of the quick-connect fitting together in order to cause the retaining tabs to snap into place.
3. Once installed, pull on both sides of the quick-connect fittings in order to make sure the connection is secure.

J 45004 Fuel Tank Siphon Hose

1. Remove the fuel fill cap.
2. Insert the adapter to the fill pipe in order to hold open the internal fill pipe door.
3. Insert the J 45004 hose through the adapter and into the tank.
4. Attach the J 45004 hose to the hose used with the hand or air operated pumping device.
5. Using the hand or air operated pumping device, drain as much fuel from the tank as possible.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Drain the fuel tank. Refer to «Fuel Tank Draining Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
3. Remove the fuel tank fill pipe. Refer to «Filler Tube Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Filler Tube Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Filler Tube Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
4. Disconnect the EVAP canister vent solenoid electrical connector.
5. Remove the EVAP canister vent solenoid from the fuel tank.
6. If equipped, remove the fuel tank shield bolts.
7. Remove the fuel tank shield.
8. Disconnect the fuel feed and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
9. Cap the fuel and EVAP lines in order to prevent possible system contamination.
10. Place a suitable adjustable jack under the fuel tank.
11. Remove the fuel tank strap bolts.
12. Remove the fuel tank straps.
13. Lower the fuel tank until the electrical connections are accessible.
14. Disconnect the fuel sending unit and fuel pressure sensor electrical connectors.
15. Completely lower the fuel tank.
16. With the aid of an assistant, place the fuel tank in a suitable work area.
17. If necessary, remove the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. If necessary, install the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. With the aid of an assistant, place the fuel tank onto the adjustable jack.
3. Raise the fuel tank until the electrical connections can be made.
4. Connect the fuel sending unit and pressure sensor electrical connectors.
5. Completely raise the fuel tank.
6. Install the fuel tank straps.
7. Install the fuel tank strap bolts. Tighten: Tighten the bolts to 40 N.m (30 lb ft).
8. Remove the adjustable jack from under the fuel tank.
9. Remove the caps from the fuel and EVAP lines.
10. Connect the fuel feed and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
11. If necessary, install the fuel tank shield.
12. Install the fuel tank shield bolts. Tighten: Tighten the bolts to 18 N.m (13 lb ft).
13. Install the EVAP canister vent solenoid to the fuel tank.
14. Connect the EVAP canister vent solenoid electrical connector.
15. Install the fuel tank fill pipe. Refer to «Filler Tube Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Filler Tube Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Filler Tube Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
16. Refill the fuel tank.
17. Install the fuel cap.
18. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) .
19. Perform the following procedure in order to inspect for leaks: Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. If equipped with a rear auxiliary tank, disconnect the fuel feed and EVAP (evaporative emission ) quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
3. Cap the fuel feed and EVAP pipes in order to prevent possible system contamination.
4. Loosen the fuel fill pipe clamp (2) at the tank.
5. Loosen the vent pipe clamp (1) at the tank.
6. Remove the fuel fill pipe and vent pipe from the tank.
7. Drain the fuel tank. Refer to «Fuel Tank Draining Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
8. Disconnect the fuel sending unit and fuel pressure sensor electrical connectors (1).
9. Remove the canister vent solenoid (CVS) line from the fuel tank clips.
10. Disconnect the fuel feed and EVAP quick connect fittings from the sending unit. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
11. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
12. Remove the fuel tank shield bolts.
13. Remove the fuel tank shield.
14. Place a suitable adjustable jack under the fuel tank.
15. Remove the fuel tank strap bolts.
16. Remove the fuel tank straps.
17. Lower the fuel tank.
18. With the aid of an assistant, place the fuel tank in a suitable work area.
19. Cap the fuel and EVAP pipes in order to prevent possible system contamination.
20. If necessary, remove the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. If necessary, install the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Remove the caps from the fuel and EVAP pipes.
3. With the aid of an assistant, place the fuel tank on the jack.
4. Raise the fuel tank.
5. Install the fuel tank straps. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
6. Install the fuel tank strap bolts. Tighten: Tighten the bolts to 40 N.m (30 lb ft).
7. Remove the jack from under the fuel tank.
8. Install the fuel tank shield.
9. Install the fuel tank shield bolts. Tighten: Tighten the bolts to 18 N.m (13 lb ft).
10. Lower the vehicle.
11. Connect the fuel feed and EVAP quick connect fittings to the sending unit. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
12. Connect the fuel sending unit and fuel pressure sensor electrical connectors (1).
13. Install the CVS line to the fuel tank clips.
14. Install the fuel fill pipe and vent pipe to the tank.
15. Tighten the vent pipe clamp (1) at the tank.
16. Tighten the fuel fill pipe clamp (2) at the tank. Tighten: Tighten the clamps to 2.5 N.m (22 lb in).
17. Remove the caps from the fuel feed and EVAP pipes.
18. If equipped with a rear auxiliary tank, connect the fuel feed and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
19. Refill the fuel tank.
20. Install the fuel fill cap.
21. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) .
22. Perform the following steps in order to inspect for leaks. Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Loosen the fuel fill pipe hose clamp (2) at the tank.
3. Loosen the fuel vent pipe hose clamp (1) at the tank.
4. Remove the fuel fill and vent hoses from the tank.
5. Drain the fuel tank. Refer to «Fuel Tank Draining Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
6. Disconnect the fuel tank pressure sensor electrical connector.
7. Disconnect the fuel feed and EVAP (evaporative emission) quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
8. Cap the fuel/EVAP lines in order to prevent possible system contamination.
9. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
10. Remove the fuel tank shield bolts.
11. Remove the fuel tank shield.
12. Place a suitable adjustable jack under the fuel tank.
13. Remove the fuel tank strap bolts.
14. Remove the fuel tank straps.
15. Lower the fuel tank.
16. With the aid of an assistant, place the fuel tank in a suitable work area.
17. If necessary, remove the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. If necessary, install the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. With the aid of an assistant, place the fuel tank on the jack.
3. Raise the fuel tank.
4. Install the fuel tank straps. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
5. Install the fuel tank strap bolts. Tighten: Tighten the bolts to 40 N.m (30 lb ft).
6. Remove the jack from under the fuel tank.
7. Install the fuel tank shield.
8. Install the fuel tank shield bolts. Tighten: Tighten the bolts to 18 N.m (13 lb ft).
9. Lower the vehicle.
10. Remove the caps from the fuel/EVAP lines.
11. Connect the fuel feed and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
12. Disconnect the fuel tank pressure sensor electrical connector.
13. Install the fuel fill and vent hoses to the tank.
14. Tighten the fuel vent pipe hose clamp (1) at the tank.
15. Tighten the fuel fill pipe hose clamp (2) at the tank. Tighten: Tighten the clamps to 2.5 N.m (22 lb in).
16. Refill the fuel tank.
17. Install the fuel fill cap.
18. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
19. Perform the following steps in order to inspect for leaks. Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Remove the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Using a slight rocking motion, while pulling straight up, remove the fuel tank pressure sensor (1).

1. Install the fuel tank pressure sensor (1).
2. Install the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Remove the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the fuel pump electrical connector.
3. Remove the fuel lever sensor electrical connector retaining clip.
4. Disconnect the fuel level sensor electrical connector.
5. Remove the fuel level sensor retaining clip.
6. Remove the fuel level sensor (1).

1. Install the fuel level sensor (1).
2. Install the fuel level sensor retaining clip.
3. Connect the fuel level sensor electrical connector.
4. Install the fuel lever sensor electrical connector retaining clip.
5. Connect the fuel pump electrical connector.
6. Install the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Remove the fuel tank filler housing to body screws (1) and retainer (2).
2. If necessary, partially drain the fuel tank. Refer to «Fuel Tank Draining Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
3. Remove the fuel tank filler housing to fuel tank fill pipe screws.
4. Remove the fuel tank filler housing.
5. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
6. Remove the fuel tank fill pipe ground wire bolt (1).
7. Remove the fuel tank fill pipe ground wire (3) anti-rotation tab from the frame hole.
8. Reposition the fuel tank fill pipe ground wire and chassis harness ground wire (2).
9. Remove the rear axle vent hose from the clip on the fuel fill pipe bracket.
10. Loosen the fuel tank fill pipe clamp (1) at the fuel tank.
11. Disconnect the recirculation line from the sending unit. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
12. Remove the fuel tank fill pipe.
13. Cap the opening on the fuel tank in order to prevent possible system contamination.

1. Remove the cap from the opening on the fuel tank.
2. Install the fuel tank fill pipe.
3. Connect the recirculation line to the sending unit. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) . NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
4. Tighten the fuel tank fill pipe clamp (1) at the fuel tank. Tighten: Tighten the clamp to 2.5 N.m (22 lb in).
5. Install the rear axle vent hose to the clip on the fuel fill pipe bracket.
6. Position the fuel tank fill pipe ground wire and chassis harness ground wire (2).
7. Install the fuel tank fill pipe ground wire (3) anti-rotation tab into the frame hole.
8. Install the fuel tank fill pipe ground wire bolt (1). Tighten: Tighten the bolt to 9 N.m (80 lb in).
9. Lower the vehicle.
10. Install the fuel tank filler housing.
11. Install the fuel tank filler housing to fuel tank fill pipe screws. Tighten: Tighten the screws to 2.3 N.m (20 lb in).
12. Install the fuel tank filler housing to body screws (1) and retainer (2). Tighten: Tighten the screws to 2.3 N.m (20 lb in).

1. If equipped with a rear auxiliary tank, disconnect the fuel and evaporative emission (EVAP) quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
2. Cap the fuel feed and EVAP pipes in order to prevent possible system contamination.
3. Loosen the fuel fill pipe clamp (2) at the tank.
4. Loosen the vent pipe clamp (1) at the tank.
5. Remove the fuel fill pipe and vent pipe from the tank.
6. Cap the fuel and vent openings in the tank in order to prevent possible system contamination.

1. Remove the caps from the fuel and vent openings in the tank.
2. Install the fuel fill pipe and vent pipe to the tank. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
3. Tighten the vent pipe clamp (1) at the tank.
4. Tighten the fuel fill pipe clamp (2) at the tank. Tighten: Tighten the clamps to 2.5 N.m (22 lb in).
5. Remove the caps from the fuel feed and EVAP pipes.
6. If equipped with a rear auxiliary tank, connect the fuel and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .

1. Loosen the fuel fill pipe hose clamp (2) at the tank.
2. Loosen the fuel vent pipe hose clamp (1) at the tank.
3. Remove the fuel fill and vent hoses from the tank.

1. Install the fuel fill and vent hoses to the tank.
2. Tighten the fuel vent pipe hose clamp (1) at the tank. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
3. Tighten the fuel fill pipe hose clamp (2) at the tank. Tighten: Tighten the clamps to 2.5 N.m (22 lb in).

J 45722 Fuel Sender Lock Ring Wrench

1. Remove the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the fuel line from the sending unit. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
3. Disconnect the evaporative emission (EVAP) line from the sending unit. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
4. Using J 45722 remove the sending unit lock ring. CAUTION: Drain the fuel from the fuel sender assembly into an approved container in order to reduce the risk of fire and personal injury. Never store the fuel in an open container.
5. Remove the sending unit and seal. Discard the seal.
6. Clean the sending unit sealing surfaces.

1. Install a NEW sending unit seal.
2. Install the sending unit.
3. Using J 45722 install the sending unit lock ring.
4. Connect the EVAP line to the sending unit. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
5. Connect the fuel line to the sending unit. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
6. Install the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
2. Disconnect the fuel feed line (1) at the engine. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
3. Disconnect the EVAP canister purge tube line (2). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
4. Cap the fuel rail and EVAP lines in order to avoid possible system contamination.
5. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
6. Remove the fuel pipe bracket nut.
7. Remove the fuel pipe bracket from the bellhousing stud.
8. Remove the heated oxygen sensor (HO2S) sensor connector from the bracket.
9. Remove the fuel line clip from the bracket on the transmission.
10. If equipped with 4-wheel drive (4WD), remove the fuel line clip from the bracket on the transfer case.
11. Remove the clip from the bracket on the frame.
12. Remove the transfer case harness from the clip bracket.
13. Thoroughly wash all contaminants from around the EHCU.
14. Disconnect the chassis electrical harness connectors from the electronic brake control module (EBCM).
15. Disconnect the brake lines from the brake pressure modulator valve (BPMV).
16. Remove the bolts (4) attaching the EHCU bracket to the frame (5).
17. Remove the EHCU (1).
18. If equipped with 4WD, remove the torsion bar bracket. Refer to «Torsion Bar Replacement»(ref-197408-S34474227302005101100000) in Front Suspension.
19. Disconnect the fuel and EVAP lines at the fuel tank. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
20. Cap the fuel and EVAP lines at the fuel tank in order to avoid possible system contamination.
21. Remove the fuel and EVAP bundle clip nuts.
22. Remove the fuel and EVAP bundle.

1. Install the fuel and EVAP bundle.
2. Install the fuel and EVAP bundle clip nuts. Tighten: Tighten the nuts to 12 N.m (106 lb in).
3. Remove the caps from the fuel and EVAP lines at the fuel tank.
4. Connect the fuel and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
5. If equipped with 4WD, install the torsion bar bracket. Refer to «Torsion Bar Replacement»(ref-197408-S34474227302005101100000) in Front Suspension.
6. Install the EHCU (1).
7. Install the bolts (4) attaching the EHCU bracket to the frame (5). Tighten: Tighten the bolts to 25 N.m (18 lb ft).
8. Connect the brake lines to the BPMV. Tighten: Tighten the fittings to 25 N.m (18 lb ft).
9. Connect the chassis electrical harness connectors to the EBCM.
10. Install the transfer case harness to the clip bracket.
11. Install the clip to the bracket on the frame.
12. If equipped with 4WD, install the fuel line clip to the bracket on the transfer case.
13. Install the fuel line clips to the brackets on the transmission.
14. Install the HO2S sensor connector to the bracket.
15. Install the fuel pipe bracket to the bellhousing stud.
16. Install the fuel pipe bracket nut. Tighten: Tighten the nut to 10 N.m (89 lb in).
17. Lower the vehicle.
18. Remove the caps from the fuel rail and EVAP line.
19. Connect the fuel feed line (1) at the engine. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
20. Connect the EVAP canister purge tube line (2). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
21. Install the fuel fill cap.
22. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
23. Use the following procedure in order to inspect for leaks: Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
2. Disconnect the fuel feed line (1) at the engine. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
3. Disconnect the EVAP canister purge tube line (2). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
4. Cap the fuel rail in order to avoid possible system contamination.
5. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
6. Remove the fuel pipe bracket nut.
7. Remove the fuel pipe bracket from the bellhousing stud.
8. Remove the fuel line clips from the brackets on the transmission.
9. If equipped with 4-wheel drive (4WD), remove the fuel line clip from the bracket on the transfer case.
10. Disconnect the fuel and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
11. Cap the fuel and EVAP lines at the fuel tank in order to avoid possible system contamination.
12. Remove the EVAP line from the clips (2) on the fuel tank.
13. Disconnect the quick connect fittings from the EVAP canister.
14. Remove the fuel and EVAP bundle nuts.
15. Remove the fuel and EVAP bundle.

1. Install the fuel and EVAP bundle.
2. Install the fuel and EVAP bundle nuts. Tighten: Tighten the nuts to 12 N.m (106 lb in).
3. Connect the quick connect fittings to the EVAP canister.
4. Install the EVAP line to the clips (2) on the fuel tank.
5. Remove the caps from the fuel and EVAP lines.
6. Connect the fuel and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
7. If equipped with 4WD, install the fuel line clip to the bracket on the transfer case.
8. Install the fuel line clips to the brackets on the transmission.
9. Install the fuel pipe bracket to the bellhousing stud.
10. Install the fuel pipe bracket nut. Tighten: Tighten the nut to 10 N.m (89 lb in).
11. Lower the vehicle.
12. Remove the caps from the fuel rail.
13. Connect the EVAP canister purge tube line (2). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
14. Connect the fuel feed line (1) at the engine. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
15. Install the fuel fill cap.
16. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
17. Perform the following procedure in order to inspect for leaks. Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
2. Disconnect the fuel feed and pressure balance lines from the front tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
3. Cap the fuel and balance lines at the fuel tank in order to avoid possible system contamination.
4. Disconnect the fuel feed and pressure balance lines from the rear tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
5. Cap the fuel and balance lines at the fuel tank in order to avoid possible system contamination.
6. Remove the rear fuel line bundle clip nuts.
7. Remove the rear fuel line bundle.

1. Install the rear fuel line bundle.
2. Install the rear fuel line bundle clip nuts. Tighten: Tighten the nuts to 12 N.m (106 lb in).
3. Remove the caps from the fuel and balance lines at the fuel tank.
4. Connect the fuel feed and pressure balance lines to the rear tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
5. Remove the caps from the fuel and balance lines at the fuel tank.
6. Connect the fuel feed and pressure balance lines to the front tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
7. Install the fuel fill cap.
8. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
9. Perform the following procedure in order to inspect for leaks. Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Remove the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect and remove the fuel feed line (1) from the sending unit and retaining clips. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
3. Cap the fuel feed and evaporative emission (EVAP) openings in order to prevent possible fuel/EVAP system contamination.

1. Remove the caps from the fuel feed/return, and EVAP lines.
2. Install and connect the fuel feed (1) line to the sending unit and retaining clips. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
3. Install the fuel tank. Refer to «Fuel Tank Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Front)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Fuel Tank Replacement (Cab/Chassis - Rear)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

Fuel System Cleaning

1. Remove the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Inspect the fuel strainer. Replace a contaminated strainer and inspect the fuel pump.
3. Inspect the fuel pump inlet for dirt and debris. Replace the fuel pump if you find dirt or debris in the fuel pump inlet.
4. Flush the fuel tank with hot water.
5. Pour the water out of the sending unit opening. Rock the tank to be sure that removal of the water from the tank is complete.
6. Install the sending unit. Refer to «Fuel Sender Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Remove the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
3. Disconnect the generator electrical connector (2).
4. Disconnect the evaporative emission (EVAP) canister purge valve electrical connector.
5. Disconnect the electronic throttle control (ETC) electrical connector (5).
6. Remove the engine harness bolt and studs.
7. Reposition the engine harness to the drivers side of the engine compartment.
8. Identify the fuel injector connectors to their corresponding injectors in order to ensure correct sequential injector firing order after reassembly.
9. Pull the top portion (2) of the connector up. Do not pull the top portion of the connector past the top of the white portion (1).
10. Push the tab (1) on the lower side of the connector in order to release the connector from the injector.
11. Repeat step 12 and step 13 for each injector connector.
12. Disconnect the fuel feed (1) line from the fuel rail. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
13. Remove the fuel rail studs.
14. Remove the fuel rail.
15. Remove and discard the fuel injector lower O-ring seals (4) from the spray tip end of each injector (3).

1. Lubricate NEW lower injector O-ring seals (4) with clean engine oil.
2. Install the NEW O-ring seals (4) onto the spray tip end of each injector (3).
3. Install the fuel rail.
4. Install the fuel rail studs. Tighten: Tighten the studs to 12 N.m (106 lb in).
5. Connect the fuel feed (1) line to the fuel rail. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
6. Connect the fuel injector electrical connectors. Install each connector onto the proper injector in order to ensure correct sequential injector firing order. Rotate the injectors as required in order to avoid stretching the wire harness.
7. Reposition the engine harness.
8. Install the engine harness bolt and studs. Tighten: Tighten the bolt/studs to 10 N.m (89 lb in).
9. Connect the ETC electrical connector (5).
10. Connect the EVAP canister purge valve electrical connector.
11. Connect the generator electrical connector (2).
12. Install the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
13. Install the fuel fill cap.
14. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
15. Use the following procedure to inspect for leaks: Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Remove the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
3. Clean any dirt from the fuel pressure dampener retainer and the surrounding area.
4. Remove the fuel pressure dampener clip (1) and dampener.
5. Remove the fuel pressure dampener backup ring.
6. Remove the fuel pressure dampener O-ring.

1. Lubricate the fuel pressure dampener O-ring with clean engine oil.
2. Install the fuel pressure dampener O-ring.
3. Install the fuel pressure dampener backup ring.
4. Install the fuel pressure dampener and clip (1).
5. Install the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
6. Install the fuel fill cap.
7. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
8. Use the following procedure to inspect for leaks: Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

Note. Use care in removing the fuel injectors in order to prevent damage to the fuel injector electrical connector pins or the fuel injector nozzles. Do not immerse the fuel injector in any type of cleaner. The fuel injector is an electrical component and may be damaged by this cleaning method.

1. Remove the fuel rail. Refer to «Fuel Rail Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Remove and discard the fuel injector retaining clip (1).
3. Remove the injector (5) from the fuel rail.
4. Remove and discard the injector O-ring seals (2, 4) from both ends of the injector.

Scheme 173

The fuel injector (1) is stamped with a part number identification (2). A 4-digit build date code (3) indicates the month (4), day (5), year (6), and shift (7) that built the injector.

1. Lubricate the NEW injector O-ring seals (2, 4) with clean engine oil.
2. Install the NEW injector O-ring seals onto the injector.
3. Install a NEW retaining clip (1) on the injector.
4. Push the fuel injector (5) into the fuel rail with the electrical connector facing outwards. The retaining clip (4) locks onto a flange on the fuel rail injector socket.
5. Install the fuel rail. Refer to «Fuel Rail Assembly Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

Fuel Injector Cleaning Procedure

Tools Required

1. J 37287 Fuel Line Shut-Off Adapters
2. J 35800-A Fuel Injector Cleaner
3. J 42873-1 3/8 Fuel Line Shut-Off Valve
4. J 42873-2 5/16 Return Pipe Shut-Off Valve
5. J 42964-1 3/8 Fuel Pipe Shut-Off Valve
6. J 42964-2 5/16 Fuel Pipe Shut-Off Valve

Note. GM Top-Engine Cleaner is the only injector cleaning agent recommended. Do not use other cleaning agents, as they may contain methanol which can damage fuel system components. Under NO circumstances should the top engine cleaner be added to the vehicles fuel tank, as it may damage the fuel pump and other system components. Do not exceed a 10 percent cleaning solution concentration. Higher concentrations may damage fuel system components. Testing has demonstrated that exceeding the 10 percent cleaning solution concentration does not improve the effectiveness of this procedure.

1. Obtain J 35800-A (2).
2. For US dealers, empty 2 pre-measured GM Top-Engine Cleaner containers, 24 ml (0.812 oz) each, GM P/N 12346535, into the J 35800-A .
3. For Canadian dealers, measure and dispense 48 ml (1.62 oz) of Top-Engine Cleaner, Canadian P/N 992872, into the J 35800-A .
4. If you are using any other brand of tank you will need a total of 96 ml (3.24 oz) of Top-Engine Cleaner mixed with 864 ml (29.16 oz) of regular unleaded gasoline.
5. Fill the injector cleaning tank with regular unleaded gasoline. Be sure to follow all additional instructions provided with the tool.
6. Electrically disable the vehicle fuel pump by removing the fuel pump relay and disconnecting the oil pressure switch connector, if equipped.
7. Disconnect the fuel feed and return line, if equipped, at the fuel rail. Plug the fuel feed and return line, if equipped, coming off the fuel rail with J 37287 , or J 42964-1 , and J 42964-2 or J 42873-1 , and J 42873-2 as appropriate for the fuel system.
8. Connect the J 35800-A to the vehicle fuel rail.
9. Pressurize the J 35800-A to 510 kPa (75 psi).
10. Start and idle the engine until it stalls due to lack of fuel. This should take approximately 15-20 minutes.
11. Disconnect J 35800-A from the fuel rail.
12. Reconnect the vehicle fuel pump relay and oil pressure switch connector, if equipped.
13. Remove J 37287 or J 42964-1 , and J 42964-2 or J 42873-1 , and J 42873-2 and reconnect the vehicle fuel feed and return lines.
14. Start and idle the vehicle for an additional 2 minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.
15. Repeat steps 1-5 of the Injector Balance Test, and record the fuel pressure drop from each injector.
16. Subtract the lowest fuel pressure drop from the highest fuel pressure drop. If the value is 15 kPa (2 psi) or less, no additional action is required. If the value is greater than 15 kPa (2 psi), replace the injector with the lowest fuel pressure drop.
17. Add one ounce of Port Fuel Injector Cleaner, GM P/N 12345104 (Canadian P/N 10953467), to the vehicle fuel tank for each gallon of gasoline estimated to be in the fuel tank. Instruct the customer to add the reminder of the bottle of Port Fuel Injector Cleaner to the vehicle fuel tank at the next fill-up.
18. Advise the customer to change brands of fuel and to add GM Port Fuel Injector Cleaner every 5 000 km (3,000 mi). GM Port Fuel Injector Cleaner contains the same additives that the fuel companies are removing from the fuel to reduce costs. Regular use of GM Port Fuel Injector Cleaner should keep the customer from having to repeat the injector cleaning procedure.
19. Road test the vehicle to verify that the customer concern has been corrected.

1. Remove the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
2. Disconnect the evaporative emission (EVAP) canister purge valve electrical connector (1).
3. Disconnect the EVAP purge tube from the purge solenoid.
4. In order to disconnect the EVAP purge tube connector (1), slide the retaining tab (2) to the release position and separate the connection.
5. Remove the EVAP canister purge valve bolt.
6. Remove the EVAP canister purge valve.

1. Install the EVAP canister purge valve.
2. Install the EVAP canister purge valve bolt. Tighten: Tighten the bolt to 10 N.m (89 lb in).
3. Connect the EVAP purge tube to the purge solenoid.
4. Connect the EVAP canister purge valve electrical connector (1).
5. Install the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Remove the harness clip from the canister vent solenoid (CVS) line.
3. Disconnect the CVS electrical connector.
4. If the vehicle is equipped with a 6 ft box, disconnect the EVAP CVS line from the canister.
5. Remove the CVS clip from the frame crossmember.
6. Push in the retainer and remove the CVS from the fuel tank clip.
7. If the vehicle is equipped with a 8 ft box, disconnect the EVAP CVS line from the canister.
8. Remove the CVS clip from the frame crossmember.
9. Push in the retainer and remove the CVS from the fuel tank clip.

1. If the vehicle is equipped with a 8 ft box, install the CVS to the fuel tank until the clip engages.
2. Install the CVS clip to the frame crossmember.
3. Connect the EVAP CVS line to the canister.
4. If the vehicle is equipped with a 6 ft box, install the CVS to the fuel tank until the clip engages.
5. Install the CVS clip to the frame crossmember.
6. Connect the EVAP CVS line to the canister.
7. Connect the CVS electrical connector.
8. Install the harness clip to the canister vent solenoid (CVS) line.
9. Lower the vehicle.

1. Disconnect the EVAP canister vent solenoid (CVS) electrical connector (1).
2. Remove the EVAP CVS valve bracket bolt (1).
3. Remove the EVAP CVS line from the clips on the fuel tank.
4. Remove the CVS valve and line.
5. Remove the EVAP CVS valve line from the CVS, if necessary.

1. Install the EVAP CVS valve line to the CVS, if necessary.
2. Install the CVS valve and line. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
3. Install the EVAP CVS valve bracket bolt (1). Tighten: Tighten the bolt to 12 N.m (106 lb in).
4. Install the EVAP CVS line to the clips on the fuel tank.
5. Connect the EVAP CVS electrical connector (1).

1. Remove the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.
2. Disconnect the fuel injector harness electrical connector (3).
3. Disconnect the evaporative emission (EVAP) purge tube at the purge solenoid.
4. To disconnect the EVAP purge tube connector (1), slide the retaining tab (2) to the release position and separate the connection.
5. Disconnect the EVAP purge tube clip from the fuel rail bracket.
6. Disconnect the EVAP purge tube at the EVAP pipe.

1. Connect the EVAP purge tube at the EVAP pipe.
2. Connect the EVAP purge tube clip to the fuel rail bracket.
3. Connect the EVAP purge tube at the purge solenoid.
4. Connect the fuel injector harness electrical connector (3).
5. Install the engine sight shield. Refer to «Engine Sight Shield Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/mechanical/#engine-mechanical-81l) in Engine Mechanical - 8.1L.

1. Remove the EVAP canister. Refer to «Evaporative Emission (EVAP) Canister Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Evaporative Emission (EVAP) Canister Replacement (Cab/Chassis)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Remove the EVAP canister line (1). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
3. Remove the EVAP canister purge line (2). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
4. Cap the fuel and EVAP lines in order to prevent possible fuel/EVAP system contamination.

1. Remove the caps from the fuel and EVAP lines.
2. Install the EVAP canister purge line (2). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
3. Install the EVAP canister line (1). Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
4. Install the EVAP canister. Refer to «Evaporative Emission (EVAP) Canister Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Evaporative Emission (EVAP) Canister Replacement (Cab/Chassis)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the fuel feed line (1) at the engine. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
3. Disconnect the EVAP canister purge tube line (2).
4. Cap the fuel rail in order to avoid possible system contamination.
5. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
6. Remove the fuel pipe bracket nut.
7. Remove the fuel pipe bracket from the bellhousing stud.
8. Remove the fuel line clip from the bracket on the transmission.
9. If equipped with 4-wheel drive (4WD), remove the fuel line clip from the bracket on the transfer case.
10. Disconnect the fuel and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
11. Cap the fuel and EVAP lines at the fuel tank in order to avoid possible system contamination.
12. Remove the fuel and EVAP bundle nuts.
13. Remove the fuel and EVAP bundle.

1. Install the fuel and EVAP bundle.
2. Install the fuel and EVAP bundle nuts. Tighten: Tighten the nuts to 12 N.m (106 lb in).
3. Remove the caps from the fuel and EVAP lines at the fuel tank.
4. Connect the fuel and EVAP quick connect fittings. Refer to «Quick Connect Fitting(s) Service (Plastic Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction) .
5. If equipped with 4WD, install the fuel line clip to the bracket on the transfer case.
6. Install the fuel line clip(s) to the bracket(s) on the transmission.
7. Install the fuel pipe bracket to the bellhousing stud.
8. Install the fuel pipe bracket nut. Tighten: Tighten the nut to 10 N.m (89 lb in).
9. Lower the vehicle.
10. Remove the cap from the fuel rail.
11. Connect the fuel feed line (1) at the engine. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
12. Connect the EVAP canister purge tube line (2).
13. Install the fuel fill cap.
14. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in Engine Electrical.
15. Use the following procedure in order to inspect for leaks: Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the fuel feed and pressure balance lines from the front tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
3. Cap the fuel and balance lines at the fuel tank in order to avoid possible system contamination.
4. Disconnect the fuel feed and pressure balance lines from the rear tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
5. Cap the fuel and balance lines at the fuel tank in order to avoid possible system contamination.
6. Remove the rear fuel line bundle clip nuts.
7. Remove the rear fuel line bundle.

1. Install the rear fuel line bundle.
2. Install the rear fuel line bundle clip nuts.
3. Remove the caps from the fuel and balance lines at the fuel tank.
4. Connect the fuel feed and pressure balance lines from the rear tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
5. Remove the caps from the fuel and balance lines at the fuel tank.
6. Connect the fuel feed and pressure balance lines from the front tank. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-48l-53l-60l-introduction__quick-connect-fittings-service-metal-collar) .
7. Install the fuel fill cap.
8. Connect the negative battery cable. Refer to «Battery Negative Cable Disconnect/Connect Procedure (Single Battery)»(ref-197347-S01049574002005101100000) or «Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery)»(ref-197347-S39973143602005101100000) in General Information.
9. Perform the following procedure in order to inspect for leaks. Turn the ignition ON, with the engine OFF, for 2 seconds. Turn the ignition OFF for 10 seconds. Turn the ignition ON, with the engine OFF. Inspect for fuel leaks.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Disconnect the EVAP canister vent solenoid (CVS) line from the canister.
3. Disconnect the fuel tank EVAP line from the canister.
4. Disconnect the canister EVAP line from the fuel bundle line.
5. Remove the EVAP canister nut.
6. Remove the EVAP canister with shield from the bracket.
7. If necessary, remove the EVAP canister from the shield, perform the following: Lift up the retaining clip on the bottom of the canister. Remove the canister from the shield.
8. If necessary, disconnect the EVAP lines from the canister.

1. If necessary, connect the EVAP lines to the canister.
2. If necessary, install the EVAP canister to the shield, perform the following: Install the canister to the shield. Ensure the retaining clip engages on the bottom of the canister. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
3. Install the EVAP canister nut. Tighten: Tighten the nut to 25 N.m (18 lb ft).
4. Connect the canister EVAP line to the fuel bundle line.
5. Connect the fuel tank EVAP line to the canister.
6. Connect the EVAP CVS line to the canister.
7. Lower the vehicle.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Disconnect the EVAP canister vent solenoid (CVS) line from the canister.
3. Disconnect the fuel tank EVAP line from the canister.
4. Disconnect the canister EVAP line from the fuel bundle line.
5. Remove the EVAP canister nuts.
6. Remove the EVAP canister.

1. Install the EVAP canister.
2. Install the EVAP canister nuts. Tighten: Tighten the nuts to 25 N.m (18 lb ft).
3. Connect the canister EVAP line to the fuel bundle line.
4. Connect the fuel tank EVAP line to the canister.
5. Connect the EVAP CVS line to the canister.
6. Lower the vehicle.

J 41413-200 EVAP Pressure/Purge Diagnostic Station

Inspection Procedure

Note. Use the EVAP Pressure/Purge Diagnostic Station J 41413 in order to provide a clean, dry, low pressure gas source. Do not substitute any other pressurized gas source. Damage may result to the EVAP system.

1. Turn OFF the ignition.
2. Remove the EVAP canister purge valve. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
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, install the EVAP canister purge valve and continue with the EVAP cleaning procedure. If carbon particles are found during the inspection procedure, continue with the EVAP cleaning procedure. 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.

EVAP Cleaning Procedure

1. Remove the EVAP canister. Refer to «Evaporative Emission (EVAP) Canister Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Evaporative Emission (EVAP) Canister Replacement (Cab/Chassis)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Turn OFF the main valve on the J 41413-200 .
3. Disconnect the hose from the diagnostic station pressure regulator.
4. Using a section of vacuum hose, connect one end to the diagnostic station pressure regulator.
5. Connect the other end of the vacuum hose to the canister side of the purge pipe.
6. Turn on the main nitrogen cylinder valve and continue to discharge nitrogen for 15 seconds.
7. If the nitrogen does not dislodge the carbon particles, replace the purge pipe. Refer to «Evaporative Emission (EVAP) Hoses/Pipes Replacement - Engine»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
8. Return the J 41413-200 to its original condition.
9. Install a new EVAP canister. Refer to «Evaporative Emission (EVAP) Canister Replacement (Pickup)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) or «Evaporative Emission (EVAP) Canister Replacement (Cab/Chassis)»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
10. Install the EVAP canister purge valve. Refer to «Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
11. Lower the vehicle.
12. Continue with the published service manual diagnostic DTC procedure.

1. Disconnect the spark plug wire from the ignition coil. Twist the spark plug boot 1/2 turn. Pull only on the boot in order to remove the wire from the ignition coil.
2. Disconnect the ignition coil electrical connector.
3. Remove the ignition coil bolts.
4. Remove the ignition coil.

Note. This component is initially installed using a self-tapping bolt(s). Care should be taken when removing and/or installing the self-tapping bolt(s). Failure to use care when removing and/or installing the self-tapping bolt(s) can lead to damage and unnecessary replacement of the self-tapping bolt(s) and/or the component the self-tapping bolt(s) is threaded into.

1. Install ignition coil.
2. Install the ignition coil bolts. Tighten: Tighten the bolts to 12 N.m (106 lb in).
3. Connect the ignition coil electrical connector.
4. Connect the spark plug wire to the ignition coil.
5. Inspect the wire for proper installation: Push sideways on the boot in order to inspect the seating. Reinstall any loose boot.

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.

1. Disconnect the spark plug wire at the spark plug. Twist the spark plug wire 1/2 turn. Pull only on the boot in order to remove the wire from the spark plug.
2. Disconnect the spark plug wire from the ignition coil. Twist each spark plug boot 1/2 turn. Pull only on the boot in order to remove the wire from the ignition coil.

1. Install the spark plug wire at the ignition coil.
2. Install the spark plug wire to the spark plug.
3. Inspect the wire for proper installation: Push sideways on the boot in order to inspect the seating. Reinstall any loose boot.

Spark Plug Inspection

1. Verify that the correct spark plug is installed. An incorrect spark plug causes driveability conditions. Refer to «Ignition System Specifications»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction__ignition-system-specifications) 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, 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 causes 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) terminals. Refer to «Ignition System Specifications»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction__ignition-system-specifications) . An excessively wide electrode gap can prevent correct spark plug operation. Inspect for the correct spark plug torque. Refer to «Ignition System Specifications»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction__ignition-system-specifications) . 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 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 intensity. Most powdery deposits will not effect spark intensity unless they form into a glazing over the electrode.

1. Remove the spark plug wire. Refer to «Spark Plug Wire Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
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.

1. Correctly position the spark plug washer.
2. Inspect the spark plug gap. Adjust the gap as needed. Specification: Spark plug gap: 1.524 mm (0.060 in)
3. Hand start the spark plug in the corresponding cylinder. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
4. Tighten the spark plug. Tighten: Tighten the plug to 20 N.m (15 lb ft) for USED heads. Tighten the plug to 30 N.m (22 lb ft) for NEW heads.
5. Install the spark plug wire. Refer to «Spark Plug Wire Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

Note. In order to prevent damage to the crankshaft position (CKP) sensor reluctor wheel/ring care must be used when removing or installing this component.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Remove the fuel line bracket nut.
3. Remove the fuel line bracket from the bellhousing stud.
4. Lower the vehicle.
5. Remove the driver side rear ignition coil bolts.
6. Reposition the ignition coil.
7. Disconnect the crankshaft position (CKP) sensor electrical connector (4).
8. Use penetrating oil and allow the oil to soak around the CKP sensor prior to removing the sensor.
9. Remove the CKP sensor bolt.
10. Twist the CKP sensor back and forth.
11. Pull the sensor straight up in order to remove the CKP sensor.
12. Inspect the CKP sensor for wear.
13. Normal CKP sensor wear will be shown on the wear strips (1) and no wear will be shown on the sensor sensing element (2).
14. Excessive or abnormal sensor wear will be shown on the sensing element (2).
15. If excessive/abnormal wear is present, replace the sensor.

1. If reusing the old sensor, inspect both O-rings for cuts, cracks, tears or damage, replace the O-rings as needed.
2. Lubricate the CKP sensor O-rings with clean engine oil. IMPORTANT: Ensure that the CKP sensor is fully seated against the crankshaft reluctor ring. The upper flange on the sensor MAY NOT seat against the engine block.
3. Install the CKP sensor.
4. If reusing the old sensor, apply thread adhesive GM P/N 12345493 (Canadian P/N 10953488) or equivalent to the threads.
5. Install the CKP sensor bolt. Tighten: Tighten the bolt to 12 N.m (106 lb in).
6. Connect the CKP sensor electrical connector (4).
7. Position the ignition coil to the rocker cover.
8. Install the driver side rear ignition coil bolts. Tighten: Tighten the bolts to 12 N.m (106 lb in).
9. Raise the vehicle
10. Install the fuel line bracket to the bellhousing stud.
11. Install the fuel line bracket nut. Tighten: Tighten the nut to 10 N.m (89 lb in).
12. Lower the vehicle.
13. Perform the CKP system variation learn procedure. Refer to «CKP System Variation Learn Procedure»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction__ckp-system-variation-learn-procedure) .

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(ref-197364-S02039416942005101100000) in General Information.
2. Remove the engine shield bolts and shield, if equipped.
3. Disconnect the camshaft position (CMP) sensor electrical connector (1).
4. Remove the CMP sensor bolt.
5. Remove the CMP sensor.
6. Inspect the CMP sensor for wear, cracks or leakage if the sensor is not being replaced.

1. Install the CMP sensor.
2. Install the CMP sensor bolt. Tighten: Tighten the bolt to 12 N.m (106 lb in).
3. Connect the CMP sensor electrical connector (1).
4. Install the engine shield and bolts, if equipped. Tighten: Tighten the bolt to 20 N.m (15 lb ft).
5. Lower the vehicle.

1. Drain the cooling system/engine block. Refer to «Draining and Filling Cooling System (w/RPO HP2)»(ref-197356-S32653343972005101100000) or «Draining and Filling Cooling System (w/o RPO HP2)»(ref-197356-S16321664992005101100000) in Engine Cooling.
2. Disconnect the knock sensor electrical connector (4).
3. Remove the knock sensor.

1. Install the knock sensor. Tighten: Tighten the sensor to 20 N.m (15 lb ft)
2. Connect the knock sensor electrical connector (4).
3. Fill the cooling system/engine block. Refer to «Draining and Filling Cooling System (w/RPO HP2)»(ref-197356-S32653343972005101100000) or «Draining and Filling Cooling System (w/o RPO HP2)»(ref-197356-S16321664992005101100000) in Engine Cooling.

1. Drain the cooling system/engine block. Refer to «Draining and Filling Cooling System (w/RPO HP2)»(ref-197356-S32653343972005101100000) or «Draining and Filling Cooling System (w/o RPO HP2)»(ref-197356-S16321664992005101100000) in Engine Cooling.
2. Disconnect the knock sensor electrical connector (3).
3. Remove the knock sensor.

1. Install the knock sensor. Tighten: Tighten the sensor to 20 N.m (15 lb ft).
2. Connect the knock sensor electrical connector (3).
3. Fill the cooling system/engine block. Refer to «Draining and Filling Cooling System (w/RPO HP2)»(ref-197356-S32653343972005101100000) or «Draining and Filling Cooling System (w/o RPO HP2)»(ref-197356-S16321664992005101100000) in Engine Cooling.

1. Loosen the air cleaner resonator outlet duct clamp at the mass air flow/intake air temperature (MAF/IAT) sensor.
2. Loosen the air cleaner resonator outlet duct clamp at the throttle body.
3. Separate the air cleaner resonator outlet duct from the MAF/IAT sensor.
4. Separate the air cleaner resonator outlet duct from the throttle body.
5. Remove the air cleaner resonator outlet duct.

1. Install the air cleaner resonator outlet duct.
2. Install the air cleaner resonator outlet duct to the throttle body.
3. Align the stud on the throttle body with the screw on the clamp. NOTE: Refer to «Fastener Notice»(ref-197335-S17275608472005101100000) in Cautions and Notices.
4. Tighten the air cleaner resonator outlet duct clamp at the throttle body. Tighten: Tighten the clamp to 4 N.m (35 lb in).
5. Install the air cleaner resonator outlet duct to the MAF/IAT sensor.
6. Tighten the air cleaner resonator outlet duct clamp at the MAF/IAT sensor. Tighten: Tighten the clamp to 4 N.m (35 lb in).

1. Remove the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the mass air flow/intake air temperature (MAF/IAT) sensor electrical connector (3).
3. Loosen the air cleaner housing cover screws.
4. Remove the air cleaner housing cover.
5. Remove the air filter element.
6. Inspect the air filter element for the following: Dust Dirt Water
7. Clean or replace the air filter element as required.

1. Install the air filter element.
2. Install the air cleaner housing cover.
3. Tighten the air cleaner housing cover screws until snug.
4. Connect the MAF/IAT sensor electrical connector (3).
5. Install the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

1. Remove the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .
2. Disconnect the mass air flow/intake air temperature (MAF/IAT) sensor electrical connector (3).
3. Pull up on the air cleaner assembly (1) in order to release the retainers from the air cleaner adapter (2).
4. If necessary, loosen the MAF/IAT sensor clamp.
5. Remove the MAF/IAT sensor.

1. If necessary, install the MAF/IAT sensor.
2. Tighten the MAF/IAT sensor clamp. Tighten: Tighten the clamp to 7 N.m (62 lb in).
3. Connect the MAF/IAT sensor electrical connector (3).
4. Install the intake air resonator. Refer to «Intake Air Resonator Replacement»(/chevrolet/cab-chassis-silverado-3500/2004-2007/remont/testing-diagnostics/#engine-controls-81l-introduction) .

Powertrain

The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The powertrain control module (PCM) is the control center of this system. The PCM monitors numerous engine and vehicle functions. The PCM constantly looks at the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The PCM also performs the diagnostic tests on various parts of the system. The PCM can recognize operational problems and alert the driver via the malfunction indicator lamp (MIL). When the PCM detects a malfunction, the PCM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. Review the components and wiring diagrams in order to determine which systems are controlled by the PCM.

The following are some of the functions that the PCM controls

1. The engine fueling
2. The ignition control (IC)
3. The knock sensor (KS) system
4. The evaporative emissions (EVAP) system
5. The secondary air injection (AIR) system (if equipped)
6. The exhaust gas recirculation (EGR) system
7. The automatic transmission functions
8. The generator
9. The A/C clutch control
10. The cooling fan control

Powertrain Control Module Function

The powertrain control module (PCM) constantly looks at the information from various sensors and other inputs and controls systems that affect vehicle performance and emissions. The PCM also performs diagnostic tests on various parts of the system. The PCM can recognize operational problems and alert the driver via the malfunction indicator lamp (MIL). When the PCM detects a malfunction, the PCM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. The input and output devices in the PCM include analog-to-digital converters, signal buffers, counters, and output drivers. The output drivers are electronic switches that complete a ground or voltage circuit when turned on. Most PCM controlled components are operated via output drivers. The PCM monitors these driver circuits for proper operation and, in most cases, can set a DTC corresponding to the controlled device if a problem is detected.

Malfunction Indicator Lamp (MIL) Operation

The malfunction indicator lamp (MIL) is located in the instrument panel cluster. The MIL will display as either SERVICE ENGINE SOON or one of the following symbols when commanded ON

Scheme 174

Scheme 175

The MIL indicates that an emissions related fault has occurred and vehicle service is required.

The following is a list of the modes of operation for the MIL

1. The MIL illuminates when the ignition is turned ON, with the engine OFF. This is a bulb test to ensure the MIL is able to illuminate.
2. The MIL turns OFF after the engine is started if a diagnostic fault is not present.
3. The MIL remains illuminated after the engine is started if the control module detects a fault. A diagnostic trouble code (DTC) is stored any time the control module illuminates the MIL due to an emissions related fault. The MIL turns OFF after three consecutive ignition cycles in which a Test Passed has been reported for the diagnostic test that originally caused the MIL to illuminate.
4. The MIL flashes if the control module detects a misfire condition which could damage the catalytic converter.
5. When the MIL is illuminated and the engine stalls, the MIL will remain illuminated as long as the ignition is ON.
6. When the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition is cycled OFF and then ON.

Trip

A trip is an interval of time during which the diagnostic test runs. A trip may consist of only a key cycle to power up the powertrain control module (PCM), allow the diagnostic to run, then cycle the key off to power down the PCM. A trip may also involve a PCM power up, meeting specific conditions to run the diagnostic test, then powering down the PCM. The definition of a trip depends upon the diagnostic. Some diagnostic tests run only once per trip (i.e., catalyst monitor) while other tests run continuously during each trip (i.e., misfire).

Warm-Up Cycle

The powertrain control module (PCM) uses warm-up cycles to run some diagnostics and to clear any diagnostic trouble codes (DTCs). A warm-up cycle occurs when the engine coolant temperature increases 22°C (40°F) from the start-up temperature. The engine coolant must also achieve a minimum temperature of 71°C (160°F). The PCM counts the number of warm-up cycles in order to clear the malfunction indicator lamp (MIL). The PCM will clear the DTCs when 40 consecutive warm-up cycles occur without a malfunction.

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.

Scheme 176

The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.

The TAC system components include the following

1. The accelerator pedal position (APP) sensor
2. The throttle body
3. The throttle actuator control (TAC) module
4. The powertrain control module (PCM)

Each of these components interface together to ensure accurate calculations and control of the throttle position.

Scheme 177

The APP sensor is mounted on the accelerator pedal assembly. The APP is actually 3 individual accelerator pedal position sensors within one housing. Three separate signal, low reference, and 5.0-volt reference circuits are used to connect the APP and the TAC module. The APP sensor 1 voltage should increase as the accelerator pedal is depressed, from below 1.0 volt at 0 percent pedal travel to above 2.0 volts at 100 percent pedal travel. APP sensor 2 voltage should decrease from above 4.0 volts at 0 percent pedal travel to below 2.9 volts at 100 percent pedal travel. APP sensor 3 voltage should decrease from above 3.8 volts at 0 percent pedal travel to below 3.1 volts at 100 percent pedal travel.

Scheme 178

The throttle body for the TAC system is similar to a conventional throttle body with a couple of exceptions. One exception being the use of a motor to control the throttle position instead of a mechanical cable. The other exception is the new design throttle position (TP) sensor. The TP sensor mounts on the side of the throttle body opposite the throttle actuator motor. The TP sensor is actually 2 individual TP sensors within one housing. Separate signal, low reference, and 5.0-volt reference circuits are used to connect the TP sensors and the TAC module. The TP sensor 1 signal voltage increases as the throttle opens, from around 1.0 volt at 0 percent throttle to above 3.5 volts at 100 percent throttle. TP sensor 2 signal voltage decreases as the throttle is opened, from around 3.8 volts at 0 percent throttle to below 1.0 volt at 100 percent throttle.

Scheme 179

The TAC module is the control center for the electronic throttle system. The TAC module and the PCM communicate via a dedicated redundant serial data circuit. The TAC module and the PCM monitor the commanded throttle position and compare the commanded position to the actual throttle position. This is accomplished by monitoring the APP and the TP sensor. These 2 values must be within a calibrated value of each other. The TAC module also monitors each individual circuit of the TP sensor and the APP to verify proper operation.

Fuel System Overview

The Fuel System is a returnless on-demand design. The fuel pressure regulator is a part of the fuel sender assembly, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

An electric turbine style fuel pump attaches to the fuel sender assembly inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel sender assembly. The function of the venturi pump is to fill the fuel sender assembly reservoir. The fuel pressure regulator, a part of the fuel sender assembly, maintains the correct fuel pressure to the fuel injection system. The fuel pump and sender assembly contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.

Fuel Tanks

The fuel tanks store the fuel supply. The primary fuel tank is located in the rear of the vehicle on the left side. On dual-tank applications, the secondary fuel tank is located in the rear of the vehicle above the spare tire. The fuel tanks are each held in place by 2 metal straps that attach to the frame. The fuel tanks are molded from high density polyethylene.

Scheme 180

Scheme 181

Scheme 182

Note. If a fuel tank filler cap requires replacement, use only a fuel tank filler cap with the same features. Failure to use the correct fuel tank filler cap can result in a serious malfunction of the fuel and EVAP system.

The fuel fill pipe has a tethered fuel filler cap. A torque-limiting device prevents the cap from being over tightened. To install the cap, turn the cap clockwise until you hear audible clicks. This indicates that the cap is correctly torqued and fully seated. A built-in device indicates that the fuel filler cap is fully seated. A fuel filler cap that is not fully seated may cause a malfunction in the emission system.

Scheme 183

The fuel sender assembly on single tank applications consists of the following major components

1. The fuel level sensor
2. The fuel tank pressure (FTP) sensor
3. The fuel tank fuel pump module
4. The fuel strainer
5. The fuel filter

The front fuel sender on dual tank applications consists of the following major components

1. The fuel level sensor
2. The fuel tank fuel pump module
3. The fuel strainer
4. The fuel filter

Scheme 184

The secondary fuel sender on dual tank applications consists of the following major components

1. The fuel level sensor (4)
2. The FTP sensor (1)
3. The rear fuel pump (2)

Scheme 185

The fuel level sensor consists of a float, a wire float arm, and a ceramic resistor cord. The position of the float arm indicates the fuel level. The fuel level sensor contains a variable resistor which changes resistance in correspondence with the amount of fuel in the fuel tank. The powertrain control module (PCM) sends the fuel level information via the class 2 circuit to the instrument panel cluster (IPC). This information is used for the instrument panel (I/P) fuel gage and the low fuel warning indicator, if applicable. The PCM also monitors the fuel level input for various diagnostics.

Fuel Pump

The fuel pump is mounted in the fuel sender assembly reservoir. The fuel pump is an electric high pressure pump. Fuel is pumped to the fuel rail at a specified flow and pressure. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions and aggressive vehicle maneuvers. The powertrain control module (PCM) controls the electric fuel pump operation through a fuel pump relay. The fuel pump flex pipe acts to dampen the fuel pulses and noise generated by the fuel pump.

Rear Fuel Pump - Dual Tank Applications Only

On dual tank applications, The rear fuel pump is located in the rear fuel tank. The rear fuel pump is powered by a secondary fuel pump relay when the fuel level drops below a predetermined value. Fuel is transferred from the rear fuel tank to the front fuel tank in order to ensure all of the usable fuel volume is available to the front fuel pump. The rear fuel pump relay supply voltage is received from the primary fuel pump relay when the front fuel pump is energized.

Fuel Strainer

The fuel strainer attaches to the lower end of the fuel sender. The fuel strainer is made of woven plastic. The functions of the fuel strainer are to filter contaminants and to wick fuel. The fuel strainer is self-cleaning and normally requires no maintenance. Fuel stoppage at this point indicates that the fuel tank contains an abnormal amount of sediment or water.

Nylon Fuel Pipes

Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature. There are 2 sizes of nylon pipes used: 9.5 mm (3/8 in) ID for the fuel feed, and 12.7 mm (1/2 in) ID for the vent. Heat resistant rubber hose or corrugated plastic conduit protect the sections of the pipes that are exposed to chafing, high temperature, or vibration.

Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle. However, if nylon fuel pipes are forced into sharp bends, the pipes kink and restrict the fuel flow. Also, once exposed to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far. Take special care when working on a vehicle with nylon fuel pipes.

Quick-Connect Fittings

Quick-connect fittings provide a simplified means of installing and connecting fuel system components. The fittings consist of a unique female connector and a compatible male pipe end. O-rings, located inside the female connector, provide the fuel seal. Integral locking tabs inside the female connector hold the fittings together.

On-Board Refueling Vapor Recovery (ORVR) System

The On-Board Refueling Vapor Recovery (ORVR) System is an on-board vehicle system designed to recover fuel vapors during the vehicle refueling operation. The flow of liquid fuel down the fuel filler pipe provides a liquid seal which prevents vapor from leaving the fuel filler pipe. An evaporative emission (EVAP) pipe transports the fuel vapor to the EVAP canister for use by the engine.

Fuel Pipe O-Rings

O-rings seal the threaded connections in the fuel system. Fuel system O-ring seals are made of special material. Service the O-ring seals with the correct service part.

Scheme 186

The fuel rail assembly attaches to the engine intake manifold. The fuel rail assembly performs the following functions

1. Positions the injectors (3) in the intake manifold
2. Distributes fuel evenly to the injectors
3. Integrates a fuel pulsation dampener (2) with the fuel metering system

Scheme 187

The Multec 2 fuel injector assembly is a solenoid operated device, controlled by the powertrain control module (PCM), that meters pressurized fuel to a single engine cylinder. The PCM energizes the high-impedance (12.2 ohms) injector solenoid (1) to open a normally closed ball valve (2). This allows fuel to flow into the top of the injector, past the ball valve, and through a director plate (3) at the injector outlet. The director plate has 2 machined holes that control the fuel flow, generating a spray of finely atomized fuel at the injector tip. Fuel from the injector tip is directed at the intake valve, causing it to become further atomized and vaporized before entering the combustion chamber. An injector stuck partly open can cause a loss of pressure after engine shutdown. Consequently, long cranking times would be noticed on some engines.

Fuel Pulsation Damper

The rapid opening and closing of the fuel injectors cause pressure fluctuation in the fuel rail. The result is that the amount of injected fuel will be more or less than the desired amount. Mounted on the fuel rail, the pulsation damper reduces these pressure fluctuations. When pressure suddenly begins top drop, the spring-loaded diaphragm extends slightly, decreasing fuel rail volume. This will momentarily prevent fuel pressure from becoming too low.

Fuel Pressure Regulator Assembly

The fuel pressure regulator is a diaphragm operated relief valve. The fuel pump pressure is on one side of the regulator and the regulator spring pressure is on the other side. The function of the fuel pressure regulator is to maintain a constant fuel pressure under all of the operating conditions. The pressure regulator DOES NOT compensate for the engine load by increasing the fuel pressure a s the engine intake manifold vacuum drops. The vent on the fuel pressure regulator is an atmospheric vent only. The fuel pressure regulator is mounted on the front fuel tank module.

Fuel Metering Modes of Operation

The powertrain control module (PCM) reads voltages from several sensors in order to determine how much fuel to give the engine. The fuel is delivered under one of several conditions called modes. The PCM controls all modes.

Starting Mode

With the ignition switch in the ON position, before engaging the starter, the powertrain control module (PCM) energizes the fuel pump relay for 2 seconds allowing the fuel pump to build up pressure. The PCM first tests speed density, then switches to the mass airflow (MAF) sensor. The PCM also uses the engine coolant temperature (ECT), the throttle position (TP), and the manifold absolute pressure (MAP) sensors to determine the proper air/fuel ratio for starting. The PCM controls the amount of fuel delivered in the starting mode by changing the pulse width of the injectors. This is done by pulsing the injectors for very short times.

Clear Flood Mode

If the engine floods, clear the engine by pushing the accelerator pedal down to the floor and then crank the engine. When the throttle position (TP) sensor is at wide open throttle (WOT), the powertrain control module (PCM) reduces the injector pulse width in order to increase the air to fuel ratio. The PCM holds this injector rate as long as the throttle stays wide open and the engine speed is below a predetermined RPM. If the throttle is not held wide open, the PCM returns to the starting mode.

Run Mode

The run mode has 2 conditions called Open Loop and Closed Loop. When the engine is first started and the engine speed is above a predetermined RPM, the system begins Open Loop operation. The powertrain control module (PCM) ignores the signal from the heated oxygen sensor (HO2S) and calculates the air/fuel ratio based on inputs from the engine coolant temperature (ECT), mass air flow (MAF), manifold absolute pressure (MAP), and throttle position (TP) sensors. The system stays in Open Loop until meeting the following conditions

1. Both HO2S have varying voltage output, showing that they are hot enough to operate properly. This depends upon the engine temperature.
2. The ECT sensor is above a specified temperature.
3. A specific amount of time has elapsed after starting the engine.

Specific values for the above conditions exist for each different engine, and are stored in the electrically erasable programmable read-only memory (EEPROM). The system begins Closed Loop operation after reaching these values. In Closed Loop, the PCM calculates the air/fuel ratio, injector on-time, based upon the signal from various sensors, but mainly from the HO2S. This allows the air/fuel ratio to stay very close to 14.7:1.

Acceleration Mode

When the driver pushes on the accelerator pedal, airflow into the cylinders increases rapidly, while fuel flow tends to lag behind. To prevent possible hesitation, the powertrain control module (PCM) increases the pulse width to the injectors to provide extra fuel during acceleration. The PCM determines the amount of fuel required based upon the throttle position (TP), the coolant temperature, the manifold absolute pressure (MAP), the mass air flow (MAF), and the engine speed.

Deceleration Mode

When the driver releases the accelerator pedal, airflow into the engine is reduced. The powertrain control module (PCM) reads the corresponding changes in throttle position (TP), manifold absolute pressure (MAP), and mass air flow (MAF). The PCM shuts OFF fuel completely if the deceleration is very rapid, or for long periods, such as long, closed-throttle coast-down. The fuel shuts OFF in order to protect the catalytic converters.

Battery Voltage Correction Mode

When the battery voltage is low, the powertrain control module (PCM) compensates for the weak spark delivered by the ignition system in the following ways

1. Increasing the amount of fuel delivered
2. Increasing the idle RPM
3. Increasing the ignition dwell time

Fuel Cutoff Mode

The powertrain control module (PCM) cuts OFF fuel from the fuel injectors when the following conditions are met in order to protect the powertrain from damage and improve driveability

1. The ignition is OFF. This prevents engine run-on.
2. The ignition is ON but there is no ignition reference signal. This prevents flooding or backfiring.
3. The engine speed is too high, above red line.
4. The vehicle speed is too high, above rated tire speed.
5. During an extended, high speed, closed throttle coast down-This reduces emissions and increases engine braking.
6. During extended deceleration, in order to protect the catalytic converters

Short Term Fuel Trim

The Short Term fuel trim values change rapidly in response to the heated oxygen sensor (HO2S) signal voltages. These changes fine tune the engine fueling. The ideal fuel trim values are around 0 percent. A positive fuel trim value indicates that the powertrain control module (PCM) is adding fuel in order to compensate for a lean condition. A negative fuel trim value indicates that the PCM is reducing the amount of fuel in order to compensate for a rich condition.

When the PCM determines that the Short Term fuel trim is out of the operating range, the following DTCs will set

1. DTC P0171 Bank 1 Too Lean
2. DTC P0172 Bank 1 Too Rich
3. DTC P0174 Bank 2 Too Lean
4. DTC P0175 Bank 2 Too Rich

Long Term Fuel Trim

The Long Term fuel trim is a matrix of cells arranged by RPM and manifold absolute pressure (MAP). Each cell of the Long Term fuel trim is a register like the short term fuel trim. As the engine operating conditions change, the powertrain control module (PCM) will switch from cell to cell to determine what Long Term fuel trim factor to use in the base pulse width equation.

While in any given cell, the PCM also monitors the Short Term fuel trim. If the Short Term fuel trim is far enough from 0 percent, the PCM will change the Long Term fuel trim value. Once the Long Term fuel trim value is changed, the value change should force the Short Term fuel trim back toward 0 percent. If the mixture is still not correct, the short term fuel trim will continue to have a large deviation from the ideal 0 percent. In this case, the Long Term fuel trim value will continue to change until the Short Term fuel trim becomes balanced. Both the Short Term fuel trim and Long Term fuel trim have limits which vary by calibration. If the mixture is off enough so that Long Term fuel trim reaches the limit of Long Term fuel trim control and still cannot correct the condition, the Short Term fuel trim would also go to the Short Term fuel trim limit of control in the same direction. If the mixture is still not corrected by both short term fuel trim and Long Term fuel trim at their extreme values, a fuel trim diagnostic trouble code (DTC) will likely result. When the PCM determines that the Long Term fuel trim is out of the operating range, the following DTCs will set

1. DTC P0171 Bank 1 Too Lean
2. DTC P0172 Bank 1 Too Rich
3. DTC P0174 Bank 2 Too Lean
4. DTC P0175 Bank 2 Too Rich

Under the conditions of power enrichment (PE), the PCM sets the Short Term fuel trim to 0 percent and freezes it there until PE is no longer in effect. This is done so the Closed Loop factor and the long term fuel trim will not try to correct for the PE condition.

EVAP System Operation

The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid valve to the atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid valve ON, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid valve OFF, fresh air is drawn through the vent solenoid valve and the vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid valve into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.

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.

Check Gas Cap Message

The powertrain control module (PCM) sends a class 2 message to the driver information center (DIC) illuminating the Check Gas Cap message when any of the following occur

1. A malfunction in the evaporative emission (EVAP) system and a large leak test fails
2. A malfunction in the EVAP system and a small leak test fails

EVAP System Components

The evaporative emission (EVAP) system consists of the following components

EVAP Canister

The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.

EVAP Purge Solenoid Valve

The EVAP purge solenoid valve controls the flow of vapors from the EVAP system to the intake manifold. The purge solenoid valve opens when commanded ON by the control module. This normally closed valve is pulse width modulated (PWM) by the control module to precisely control the flow of fuel vapor to the engine. The valve will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.

EVAP Vent Solenoid Valve

The EVAP vent solenoid valve controls fresh airflow into the EVAP canister. The valve is normally open. The control module commands the valve ON, closing the valve during some EVAP tests, allowing the system to be tested for leaks.

Fuel Tank Pressure Sensor

The fuel tank pressure (FTP) sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. A high FTP sensor voltage indicates a low fuel tank pressure or vacuum. A low FTP sensor voltage indicates a high fuel tank pressure.

EVAP Service Port

The EVAP service port is located in the EVAP purge pipe between the EVAP purge solenoid valve and the EVAP canister. The service port is identified by a green colored cap.

Electronic Ignition (EI) System Description

The electronic ignition (EI) system is responsible for producing and controlling a high energy secondary spark. This spark is used to ignite the compressed air/fuel mixture at precisely the correct time. This provides optimal performance, fuel economy, and control of exhaust emissions. This ignition system consists of a separate ignition coil connected to each spark plug by a short secondary wire. The driver modules within each coil assembly are commanded ON/OFF by the powertrain control module (PCM). The PCM primarily uses engine speed and position information from the crankshaft and camshaft position (CMP) sensors to control the sequence, dwell, and timing of the spark. The EI system consists of the following components

Crankshaft Position (CKP) Sensor

The crankshaft position (CKP) sensor is a three wire sensor based on the magneto resistive principle. A magneto resistive sensor uses two magnetic pickups between a permanent magnet. As an element such as a reluctor wheel passes the magnets the resulting change in the magnetic field is used by the sensor electronics to produce a digital output pulse. The PCM supplies a 12-volt, low reference, and signal circuit to the CKP sensor. The sensor returns a digital ON/OFF pulse 24 times per crankshaft revolution.

Crankshaft Reluctor Wheel

The crankshaft reluctor wheel is mounted on the rear of the crankshaft. The wheel is comprised of four 90 degree segments. Each segment represents a pair of cylinders at TDC, and is further divided into six 15 degree segments. Within each 15 degree segment is a notch of 1 of 2 different sizes. Each 90 degree segment has a unique pattern of notches. This is known as pulse width encoding. This pulse width encoded pattern allows the PCM to quickly recognize which pair of cylinders are at top dead center (TDC). The reluctor wheel is also a dual track-or mirror image-design. This means there is an additional wheel pressed against the first, with a gap of equal size to each notch of the mating wheel. When one sensing element of the CKP sensor is reading a notch, the other is reading a set of teeth. The resulting signals are then converted into a digital square wave output by the circuitry within the CKP sensor.

Camshaft Position (CMP) Sensor

The CMP sensor is also a magneto resistive sensor, with the same type of circuits as the CKP sensor. The CMP sensor signal is a digital ON/OFF pulse, output once per revolution of the camshaft. The CMP sensor information is used by the PCM to determine the position of the valve train relative to the CKP.

Camshaft Reluctor Wheel

The camshaft reluctor wheel is either pressed onto the camshaft or part of the timing gear depending on the application. The feature-or target- is read in a radial or axial fashion respectively. The wheel is a smooth track, half of which is of a lower profile than the other half. This feature allows the CMP sensor to supply a signal as soon as the key is turned ON, since the CMP sensor reads the track profile, instead of a notch.

Ignition Coils

Each ignition coil has an ignition 1 feed and a ground. The PCM supplies a low reference and an ignition control (IC) circuit. Each ignition coil contains a solid state driver module. The PCM will command the IC circuit ON, this allows the current to flow through the primary coil windings for the appropriate time or dwell. When the PCM commands the IC circuit OFF, this will interrupt current flow through the primary coil windings. The magnetic field created by the primary coil windings will collapse across the secondary coil windings, which induces a high voltage across the spark plug electrodes. The coils are current limited to prevent overloading if the IC current is held high too long. The spark plugs are connected to their respective coils by a short secondary wire. The spark plugs are tipped with iridium for long life and efficiency.

Powertrain Control Module (PCM)

The PCM controls all ignition system functions, and constantly corrects the basic spark timing. The PCM monitors information from various sensor inputs that include the following

1. The throttle position (TP) sensor
2. The engine coolant temperature (ECT) sensor
3. The mass air flow (MAF) sensor
4. The intake air temperature (IAT) sensor
5. The vehicle speed sensor (VSS)
6. The transmission gear position or range information sensors
7. The engine knock sensors (KS)

Modes of Operation

There is one normal mode of operation, with the spark under PCM control. If the CKP pulses are lost the engine will not run. The loss of a CMP signal may result in a longer crank time since the PCM cannot determine which stroke the pistons are on. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.

Purpose

The knock sensor (KS) system enables the control module to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The control module uses the KS system to test for abnormal engine noise that may indicate detonation, also known as spark knock.

Sensor Description

This knock sensor (KS) system uses one or 2 broadband one-wire sensors. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration, or noise, level. The amplitude and frequency are dependent upon the level of knock that the KS detects. The control module receives the KS signal through a signal circuit. The KS ground is supplied by the engine block through the sensor housing.

One way the control module monitors the system is by output of a bias voltage on the KS signal wire. The bias voltage creates a voltage drop that the control module monitors and uses to help diagnose KS faults. The KS noise signal rides along this bias voltage, and due to the constantly fluctuating frequency and amplitude of the signal, will always be outside of the bias voltage parameters.

Another way the control module monitors the system is by learning the average normal noise output from the KS. The control module learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the RPM range. The control module uses the minimum noise level to calculate a noise channel. The control module uses this noise channel, and the KS signal that rides along the noise channel, in much the same way as the bias voltage type does. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the normal KS signal.

In order to determine which cylinders are knocking, the control module only uses KS signal information when each cylinder is near top dead center (TDC) of the firing stroke. If the control module has determined that knock is present, it will retard the ignition timing to attempt to eliminate the knock. The control module will always try to work back to a zero compensation level, or no spark retard. An abnormal KS signal will fall within the noise channel or will not be present. KS diagnostics are calibrated to detect faults with the KS circuitry inside the control module, the KS wiring, or the KS voltage output.

Air Intake System Description

The primary function of the air intake system is to provide filtered air to the engine. The system uses a cleaner element mounted in a housing. The cleaner housing is remotely mounted and uses intake ducts to route the incoming air into the throttle body. The secondary function of the air intake system is to muffle air induction noise. This is achieved through the use of resonators attached to the air intake ducts. the resonators are tuned to the specific powertrain. The mass air flow (MAF) sensor is attached to the outlet of the air cleaner housing. The air cleaner life indicator is located on an intake duct between the air cleaner housing and the throttle plate.

Special Tools

Special Tools Illustration Tool Number/Description J 23738-A Vacuum Pump J 26792 Spark Tester J 33431-B Signal Generator and Instrument Panel Tester J 34730-1A Fuel Pressure Gage J 34730-2C TBI Harness Test Lamp J 34730-405 Injector Test Lamp J 35616-A Connector Test Adapter Kit J 35800-A Fuel Injector Cleaner J 37287 Fuel Line Shut-Off Adapters J 38522 Variable Signal Generator J 39021 Fuel Injector Coil and Balance Tester J 39021-380 Fuel Injector Test Harness J 41413-200 Evaporative Emissions System Tester (EEST) J 41413-SPT High Intensity White Light J 41413-VLV EVAP Service Port Vent Fitting J 41415-40 Fuel Tank Cap Adapter J 41416 Ultrasonic Leak Detector J 41769 Fuel Line Quick Disconnect Tool J 42598 Vehicle Data Recorder J 42873-1 3/8 Fuel Line Shut-Off Adapter J 42873-2 5/16 Fuel Line Shut-Off Adapter J 42964-1 3/8 Fuel Pipe Shut-Off Valve J 42964-2 5/16 Fuel Pipe Shut-Off Valve J 43013 Fuel Injector Assembly Removal Tool J 43178 Fuel Line Disconnect Tool J 43244 Relay Puller Pliers J 44175 Fuel Composition Tester J 45004 Siphon Hose J 45722 Fuel Sender Lock Ring Wrench

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See also:
• DTC P0315
• Engine Sight Shield Replacement
• Fuel Pressure Relief Procedure
• Quick Connect Fitting(s) Service (Metal Collar)
• Intake Air Resonator Replacement
• Ignition System Specifications
• CKP System Variation Learn Procedure