Page 1 of 14 2004 Chevrolet TrailBlazer - 4WD Bravada, Envoy, Rainier, TrailBlazer (VIN S/T) Service Manual Engine Engine Mechanical - 4.8L, 5.3L, and 6.0L Repair Instructions - On Vehicle Document ID: 837680 Intake Manifold Replacement Removal Procedure Important: The intake manifold, throttle body, fuel rail, and injectors may be removed as an assembly. If not servicing the individual components, remove the manifold as a complete assembly. 1. Remove the air cleaner outlet duct. Refer to Air Cleaner Resonator Outlet Duct Replacement in Engine Controls. 2. Relieve the fuel system pressure. Refer to Fuel Pressure Relief in Engine Controls. 3. Disconnect the air conditioning (A/C) compressor pressure switch electrical connector (2). 4. Remove the harness clip from the cylinder head. 2009 General Motors Corporation. All rights reserved.
Page 2 of 14 5. Disconnect the mass air flow (MAF)/intake air temperature (IAT) sensor electrical connector (1). 6. Remove the harness clips from the fuel rail. 7. Disconnect the following electrical connectors: Main coil (1) Electronic throttle control (ETC) (2) Fuel injectors (3) 8. Perform the following steps in order to disconnect the fuel injector electrical connector.
Page 3 of 14 8.1. Mark the connectors to their corresponding injectors to ensure correct reassembly. 8.2. Pull the connector position assurance (CPA) retainer (2) on the connector up 1 click. 8.3. Push the tab (1) on the connector in. 8.4. Disconnect the fuel injector electrical connector. 8.5. Repeat the steps for each injector electrical connector. 9. Disconnect the generator electrical connector. 10. Disconnect the following electrical connectors: Evaporative emission (EVAP) purge solenoid (1) Knock sensor (2) Manifold absolute pressure (MAP) sensor (3)
Page 4 of 14 Main coil (5) Fuel injectors (4) 11. Remove the electrical harness clips from the fuel rail. 12. Remove the knock sensor harness electrical connector from the intake manifold. 13. Remove the positive crankcase ventilation (PCV) hose. 14. Remove the heater water shutoff valve actuator inlet hose from the intake manifold.
Page 5 of 14 15. Remove the evaporative emission (EVAP) purge solenoid vent tube by performing the following: 15.1. Remove the EVAP tube end from the solenoid. 15.2. Squeeze the EVAP pipe quick connect fitting retainer together. 15.3. Remove the EVAP tube end from the vapor pipe. 16. Remove the vacuum brake booster hose from the rear of the intake manifold.
Page 6 of 14 17. Remove the upper engine wire harness retainer nut (1). 18. Reposition the upper engine wire harness aside. 19. Remove the intake manifold bolts. 20. Remove the intake manifold.
Page 7 of 14 21. Remove the intake manifold gaskets (1) from the intake manifold. 22. Discard the old intake manifold gaskets. 23. If necessary, clean and inspect the intake manifold. Refer to Intake Manifold Cleaning and Inspection. Installation Procedure 1. Install NEW intake manifold gaskets (1) to the intake manifold.
Page 8 of 14 2. Install the intake manifold. 3. Apply a 5 mm (0.20 in) bead of threadlock GM P/N 12345382, (Canadian P/N 10953489) or equivalent to the threads of the intake manifold bolts. Notice: Refer to Fastener Notice in the Preface section. 4. Install the intake manifold bolts. Tighten 1. Tighten the bolts a first pass in sequence to 5 N m (44 lb in). 2. Tighten the bolts a final pass in sequence to 10 N m (89 lb in).
Page 9 of 14 5. Route the electrical harness into position over the engine. 6. Install the engine harness bracket nut (1). Tighten Tighten the nut to 10 N m (89 lb in). 7. Install the vacuum brake booster hose to the rear of the intake manifold.
Page 10 of 14 8. Install the EVAP purge solenoid vent tube. 9. Install the heater water shutoff valve actuator inlet hose to the intake manifold.
Page 11 of 14 10. Install the PCV hose. 11. Install the knock sensor harness electrical connector to the intake manifold. 12. Connect the following electrical connectors: EVAP purge solenoid (1) Knock sensor (2) MAP sensor (3) Main coil (5) Fuel injectors (4)
Page 12 of 14 13. Perform the following steps in order to connect the fuel injector electrical connectors. 13.1. Install the connectors to their corresponding injectors to ensure correct reassembly. 13.2. Connect the fuel injector electrical connector. 13.3. Push the CPA retainer (2) on the connector in one click. 13.4. Repeat the steps for each injector electrical connector. 14. Install the harness clips to the fuel rail. 15. Connect the generator electrical connector.
Page 13 of 14 16. Connect the following electrical connectors: Main coil (1) ETC (2) Fuel injectors (3) 17. Install the electrical harness clips to the fuel rail. 18. Connect the A/C compressor pressure switch electrical connector (2). 19. Install the harness clip to the cylinder head.
Page 14 of 14 20. Connect the MAF/IAT sensor electrical connector (1). 21. Install the air cleaner outlet duct. Refer to Air Cleaner Resonator Outlet Duct Replacement in Engine Controls. 22. Install the fuel fill cap. 23. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. 24. Use the following procedure in order to inspect for leaks: 24.1. Turn the ignition ON, with the engine OFF, for 2 seconds. 24.2. Turn the ignition OFF for 10 seconds. 24.3. Turn the ignition ON, with the engine OFF. 24.4. Inspect for fuel leaks.