Fuel and Emissions Systems Acura TSX I

Scheme 1

Intermittent Failures

The term "intermittent failure" means a system may have had a failure, but it checks OK now. If the malfunction indicator lamp (MIL) on the dash does not come on, check for poor connections or loose terminals at all connectors related to the circuit that you are troubleshooting. If the MIL was on but then went out, the original problem may be intermittent.

Service information

Some DTCs or symptoms can be caused by a combination of ECM/PCM software and specific driving habits. Periodically, new ECM/PCM software or new service procedures may become available. Always check online for the latest software or service information related to the DTCs or symptoms you are troubleshooting.

Opens and Shorts

"Open" and "Short" are common electrical terms. An open is a break in a wire or at a connection. A short is an accidental connection of a wire to ground or to another wire. In simple electronics, this usually means something won't work at all. With complex electronics (such as ECMs and PCMs) this can sometimes mean something works, but not the way it's supposed to.

How to Use the HDS (Honda Diagnostic System)

If the MIL (malfunction indicator lamp) has come on

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1. Start the engine and check the MIL (A). NOTE: If the ignition switch is turned ON (II), and the engine is not started, the MIL will stay on for 15-20 seconds (see «MALFUNCTION INDICATOR LAMP (MIL) INDICATION (IN RELATION TO READINESS CODES)»(/acura/tsx/i-2003-2008/remont/auxiliary-emission-control-systems/#fuel-and-emissions-systems) ).
2. If the MIL stays on, connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
3. Turn the ignition switch ON (II).
4. Make sure the HDS communicates with the ECM/PCM, and other vehicle systems. If it doesn't, go to '04-06 models «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) , '07-08 models «'07-08 MODELS»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system) .
5. Check the diagnostic trouble code (DTC) and note it. Also check the freeze data and/or on-board snapshot data, and download any data found. Then refer to the indicated DTCs troubleshooting, and begin the appropriate troubleshooting procedure. NOTE: Freeze data indicates the engine conditions when the first malfunction, misfire, or fuel trim malfunction was detected. The HDS can read the DTC, freeze data, on-board snapshot, current data, and other engine control module (ECM)/powertrain control module (PCM) data. For specific operations, refer to the user's manual that came with the HDS.
6. If no DTCs are found, go to «MIL CIRCUIT TROUBLESHOOTING»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system__mil-circuit-troubleshooting) . If the MIL did not stay on If the MIL did not stay on but there is a driveability problem, do the symptom troubleshooting. If you can't duplicate the DTC Some of the troubleshooting requires you to reset the ECM/PCM and try to duplicate the DTC. If the problem is intermittent and you can't duplicate the code, do not continue through the procedure. To do so will only result in confusion and possibly, a needlessly replaced ECM/PCM.

HDS Clear Command

The ECM/PCM stores various specific data to correct the system even if there is no electrical power such as when the battery negative terminal or No. 8 Fl ECU (ECM/PCM) (15 A) fuse are disconnected. Stored data based on failed parts should be cleared by using the "CLEAR COMMAND" of the HDS, if parts are replaced.

The HDS has three kinds of clear commands to meet this purpose. They are DTC clear, ECM/PCM reset, and crank (CKP) pattern clear. DTC clear command erases all stored DTC codes, freeze data, readiness codes, and on-board snapshot. This must be done with the HDS after reproducing the DTC during troubleshooting. The ECM/PCM reset command erases all stored DTC codes, freeze data, readiness codes, on-board snapshot, and all specific data to correct the system except crank (CKP) pattern. If the crank (CKP) pattern data in the ECM/PCM was cleared, you must do the crank (CKP) pattern learn procedure. The crank (CKP) pattern clear command erases only CKP pattern data. This command is for repair of a misfire or the CKP sensor.

Scan Tool Clear Command

If you are using a generic scan tool to clear commands, be aware that there is only one setting for clearing the ECM/PCM, and it clears all commands at the same time (crank (CKP) pattern learn, idle learn, readiness codes, freeze data, on-board snapshot, and DTCs). After you clear all commands, you then need to do these procedures, in this order: ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ); crank (CKP) pattern learn procedure; Test-drive to set readiness codes to complete (see CATALYTIC CONVERTER MONITOR AND READINESS CODE ).

DTC Clear

1. Clear the DTC with the HDS while the engine is stopped.
2. Turn the ignition switch OFF.
3. Turn the ignition switch ON (II), and wait 30 seconds.
4. Turn the ignition switch OFF, and disconnect the HDS from the DLC.

ECM/PCM Reset

This command clears stored specific data from each vehicle such as DTCs, freeze data, on-board snapshot and readiness codes. It does not clear crank (CKP) Pattern data.

1. Reset the ECM/PCM with the HDS while the engine is stopped.
2. Turn the ignition switch OFF.
3. Turn the ignition switch ON (II), and wait 30 seconds.
4. Turn the ignition switch OFF, and disconnect the HDS from the DLC.
5. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/i-2003-2008/remont/engine-control-systems/#idle-control-system__ecmpcm-idle-learn-procedure) ).

Scheme 4

1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
2. Turn the ignition switch ON (II).
3. Make sure the HDS communicates with the ECM/PCM, and other vehicle systems. If it doesn't, go to '04-06 models «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) , '07-08 models «'07-08 MODELS»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system) .
4. Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.
5. Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.

Learn Procedure (without the HDS)

1. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on.
2. Test-drive the vehicle on a level road: Decelerate (with the throttle fully closed) from an engine speed of 2,500 rpm down to 1,000 rpm with the A/T in 2 position, or M/T in 1st gear.
3. Repeat step 2 above several times.
4. Turn the ignition switch OFF.
5. Turn the ignition switch ON (II), and wait 30 seconds. The crank (CKP) pattern learn procedure is complete.

How to End a Troubleshooting Session (required after any troubleshooting)

1. Reset the ECM/PCM with the HDS.
2. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/i-2003-2008/remont/engine-control-systems/#idle-control-system__ecmpcm-idle-learn-procedure) ).
3. Turn the ignition switch OFF.
4. Disconnect the HDS from the DLC. NOTE: The ECM/PCM is part of the immobilizer system. If you replace the ECM/PCM, it will have a different immobilizer code. In order for the engine to start, you must rewrite the immobilizer code with the HDS.

How to Troubleshoot Circuits at the ECM/PCM Connectors

Special Tools Required

1. Digital multimeter KS-AHM-32-003 (1) or a commercially available digital multimeter
2. Backprobe set 07SAZ-001000A (2)

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1. Connect the backprobe adapters (A) to the stacking patch cords (B), and connect the cords to a digital multimeter (C).
2. Using the wire insulation as a guide for the contoured tip of the backprobe adapter, gently slide the tip into the connector from the wire side until it touches the end of the wire terminal.
3. If you cannot get to the wire side of the connector or the wire side is sealed (A), disconnect the connector and probe the terminals (B) from the terminal side. Do not force the probe into the connector. NOTE: Do not puncture the insulation on a wire. Punctures can cause poor or intermittent electrical connections.

Updating the ECM/PCM

Special Tools Required

1. Honda diagnostic system (HDS) tablet tester
2. Honda interface module (HIM) and an iN workstation with HDS and CM update software
3. HDS pocket tester
4. GNA-600 and an iN workstation with HDS and CM update software

Note. Use this procedure when you need to update the ECM/PCM during a troubleshooting procedure. Make sure the HDS/HIM has the latest software version downloaded from the iN (interactive network). Before you update the ECM/PCM, make sure the battery in the vehicle is fully charged, and connect a jumper battery (not a battery charger) to maintain system voltage. Never turn the ignition switch OFF during the update. If there is a problem with the update, leave the ignition switch ON. To prevent ECM/PCM damage, do not operate anything electrical (headlights, audio system, brakes, A/C, power windows, moonroof (if equipped), door locks, etc.) during the update. To ensure the latest program is installed, do an ECM/PCM update whenever the ECM/PCM is substituted or replaced. You cannot update an ECM/PCM with a program it already has. It will only accept a new program. If you need to diagnose the Honda interface module (HIM) because the HIM's red (# 3) light came on or was flashed during the update, leave the ignition switch in the ON (11) position when you disconnect the HIM from the data link connector (DLC). This will prevent ECM/PCM damage.

Scheme 7

1. Turn the ignition switch ON (II), but do not start the engine.
2. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
3. Make sure the HDS communicates with the ECM/PCM, and other vehicle systems. If it doesn't, go to '04-06 models «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) , '07-08 models «'07-08 MODELS»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system) . If you are returning from the DLC circuit troubleshooting, skip steps 4 to 5 and clean the throttle body after updating the ECM/PCM (see «THROTTLE BODY CLEANING»(/acura/tsx/i-2003-2008/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).
4. Select the INSPECTION MENU with the HDS.
5. Select the ETCS TEST, then select the TP POSITION CHECK, and follow the HDS screen prompts. NOTE: If the TP POSITION CHECK indicates FAILED, continue this procedure.
6. Exit the HDS, then select the update program, and follow the screen prompts to update the ECM/PCM.
7. If the software in the ECM/PCM is the latest, disconnect the HDS/HIM from the DLC, and go back to the procedure that you were doing. If the software in the ECM/PCM is not the latest, follow the instructions on the screen. If prompted to choose the PGM-FI system or the A/T system, make sure you update both. NOTE: If the ECM/PCM update system requires you to cool the ECM/PCM, follow the instructions on screen. If you run into a problem during the update procedure, (programming takes over 15 minutes, status bar goes over 100 %, D or immobilizer light flashes, HDS tablet freezes, etc.), follow these steps to minimize the chance of damaging the ECM/PCM: Leave the ignition switch in the ON (II) position. Connect a jumper battery (do not connect a battery charger). Shut down the HDS. Disconnect the HDS from the DLC. Reboot the HDS. Reconnect the HDS to the DLC, and try the update procedure again.
8. If the TP POSITION CHECK failed in step 5 , clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/tsx/i-2003-2008/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).
9. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/i-2003-2008/remont/engine-control-systems/#idle-control-system__ecmpcm-idle-learn-procedure) ).
10. Do the crank (CKP) pattern learn procedure.

Substituting the ECM/PCM

Special Tools Required

1. Honda diagnostic system (HDS) tablet tester
2. Honda interface module (HIM) and an iN workstation with HDS and CM update software
3. HDS pocket tester
4. GNA-600 and an iN workstation with HDS and CM update software

Note. Use this procedure when you need to substitute a known-good ECM/PCM during troubleshooting procedures.

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Scheme 9

1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
2. Turn the ignition switch ON (II).
3. Make sure the HDS communicates with the ECM/PCM. If it doesn't, go to «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) , «'07-08 MODELS»(/acura/tsx/i-2003-2008/remont/testing-diagnostics/#pgm-fi-system) '07-08 models . If you are returning from DLC circuit troubleshooting, skip step 5 to 10 , and clean the throttle body after substituting the ECM/PCM (see «THROTTLE BODY CLEANING»(/acura/tsx/i-2003-2008/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).
4. Select the INSPECTION MENU with the HDS.
5. Select the ETCS TEST, then select the TP POSITION CHECK, and follow the screen prompts. NOTE: If the TP POSITION CHECK indicates FAILED, continue this procedure.
6. Turn the ignition switch OFF.
7. Jump the SCS line with the HDS.
8. Remove the center lower covers (A).
9. Remove the duct (B).
10. Disconnect the ECM/PCM connectors (C).
11. Remove the bolts (D), then remove the ECM/PCM (E).
12. Install the parts in the reverse order of removal.
13. Turn the ignition switch ON (II). NOTE: For '05-08 models: DTC P0630 "VIN Not Programmed or Mismatch" may be stored because the VIN has not been programmed into the ECM/PCM; ignore it, and continue this procedure.
14. Manually input the VIN to the ECM/PCM with the HDS.
15. Update the ECM/PCM if it does not have the latest software.
16. Select the IMMOBI SYSTEM with the HDS.
17. Enter the immobilizer code using the ECM/PCM replacement procedure in the HDS; this allows you to start the engine.
18. Reset the ECM/PCM with the HDS.
19. If the TP POSITION CHECK failed in step 5 , clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/tsx/i-2003-2008/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).
20. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/i-2003-2008/remont/engine-control-systems/#idle-control-system__ecmpcm-idle-learn-procedure) ).
21. Do the crank (CKP) pattern learn procedure.

OBD Status

The OBD status shows the current system status of each DTC and all of the parameters. This function is used to see if the repair was successfully completed. The results of diagnostic tests for the DTC are displayed as

1. PASSED: The on board diagnosis is successfully finished.
2. FAILED: The on board diagnosis has finished but failed.
3. EXECUTING: The vehicle is in enable criteria conditions for the DTC and the on board diagnosis is running.
4. NOT COMPLETED: The on board diagnosis was running but is out of the enable conditions of the DTC.
5. OUT OF CONDITION: The vehicle has stayed out of the enable conditions for the DTC.

DTC Troubleshooting Index

DTC TROUBLESHOOTING INDEX

Symptom Troubleshooting Index

When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.

SYMPTOM TROUBLESHOOTING INDEX

Electronic Control System

The functions of the fuel and emission control systems are managed by the engine control module (ECM) on vehicles with manual transmissions or the powertrain control module (PCM) on vehicles with automatic transmissions.

Self-Diagnosis

The ECM/PCM detects a failure of a signal from a sensor or another control unit and stores a Temporary DTC or a DTC. Depending on the failure, a DTC is stored in either the first or the second drive cycle. When a DTC is stored, the ECM/PCM turns on the malfunction indicator lamp (MIL) by a signal sent to the gauge via F-CAN.

1. One Drive Cycle Detection Method When an abnormality occurs in the signal from a sensor or another control unit, the ECM/PCM stores a DTC for the failure and turns on the MIL immediately.
2. Two Drive Cycle Detection Method When an abnormality occurs in the signal from a sensor or another control unit in the first drive cycle, the ECM/PCM stores a Temporary DTC. If the failure continues in the second drive cycle, the ECM/PCM stores a DTC and turns on the MIL.

Fail-safe Function

When an abnormality occurs in the signal from a sensor or another control unit, the ECM/PCM ignores that signal and substitutes a pre-programmed value for them that allows the engine to continue running. This causes a DTC to be stored and the MIL to come on.

MIL Bulb Check and Readiness Code Condition

When the ignition switch is turned ON (II), the ECM/PCM turns on the MIL via the F-CAN circuit for about 15 to 20 seconds to check the bulb condition. If any readiness codes are not set to complete, the MIL flashes five times. If all readiness codes are set to complete, the MIL goes off.

Self Shut Down (SSD) Mode

After the ignition switch is turned OFF, the ECM/PCM stays on (up to 15 minutes). If the ECM/PCM connector is disconnected during this time, the ECM/PCM may be damaged. To cancel this mode, disconnect the negative cable from the battery or jump the SCS line with the HDS after the ignition switch is turned OFF.

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Note. Standard battery voltage is about 12 V.

TERMINAL DESCRIPTION (CONNECTOR A)

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Note. Standard battery voltage is about 12 V.

TERMINAL DESCRIPTION (CONNECTOR B)

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Note. Standard battery voltage is about 12 V.

TERMINAL DESCRIPTION (CONNECTOR C)

Scheme 18

Note. Standard battery voltage is about 12 V.

TERMINAL DESCRIPTION (CONNECTOR D)

Scheme 19

Note. Standard battery voltage is about 12 V.

TERMINAL DESCRIPTION (CONNECTOR E)

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Scheme 21

PGM-FI System

The programmed fuel injection (PGM-FI) system is a sequential multiport fuel injection system.

Air Conditioning (A/C) Compressor Clutch Relay

When the ECM/PCM receives a demand for cooling from the A/C system, it delays the compressor from being energized, and enriches the air fuel mixture to assure smooth transition to the A/C mode.

Air Fuel Ratio (A/F) Sensor

The A/F sensor operates over a wide air/fuel range. The A/F sensor is installed upstream of the TWC, and sends signals to the ECM/PCM which varies the duration of fuel injection accordingly.

Scheme 22

Barometric Pressure (BARO) Sensor

The BARO sensor is inside the ECM/PCM. It converts atmospheric pressure into a voltage signal that modifies the basic duration of the fuel injection discharge.

Camshaft Position (CMP) Sensor B

CMP sensor B detects the position of the No. 1 cylinder as a reference for sequential fuel injection to each cylinder.

Scheme 23

Crankshaft Position (CKP) Sensor

The CKP sensor detects crankshaft speed and is used by the ECM/PCM to determine ignition timing and timing for fuel injection of each cylinder as well as detecting engine misfire.

Scheme 24

Engine Coolant Temperature (ECT) Sensor ('04-05 models)/Engine Coolant Temperature (ECT) Sensors 1 and 2 ('06-08 models)

ECT sensor ('04-05 models)/ECT sensor 1 and 2 ('06-08 models) is a temperature dependent resistor (thermistor). The resistance decreases as the engine coolant temperature increases.

Scheme 25

Ignition Timing Control

The ECM/PCM contains the memory for basic ignition timing at various engine speeds and manifold absolute pressures. It also adjusts the timing according to engine coolant temperature and intake air temperature.

Injector Timing and Duration

The ECM/PCM contains the memory for basic discharge duration at various engine speeds and manifold pressures. The basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors to obtain the final discharge duration.

By monitoring long term fuel trim, the ECM/PCM detects long term malfunctions in the fuel system and sets a diagnostic trouble code (DTC).

Intake Air Temperature (IAT) Sensor

The IAT sensor is a temperature dependent resistor (thermistor). The resistance of the thermistor decreases as the intake air temperature increases.

Scheme 26

Knock Sensor

The knock control system adjusts the ignition timing to minimize knock.

Scheme 27

Malfunction Indicator Lamp (MIL) Indication (In relation to Readiness Codes)

The vehicle has certain "readiness codes" that are part of the on-board diagnostics for the emissions systems. If the vehicle's battery has been disconnected or gone dead, if the DTCs have been cleared, or if the ECM/PCM has been reset, these codes are reset. In some states, part of the emissions testing is to make sure these codes are set to complete. If all of them are not set to complete, the vehicle may fail the test, or the test cannot be finished.

To check if the readiness codes are set to complete, turn the ignition switch ON (II), but do not start the engine. The MIL will come on for 15-20 seconds. If it then goes off, the readiness codes are complete. If it flashes five times, one or more readiness codes are not complete. To set each code, drive the vehicle or run the engine as described in the procedures (see MALFUNCTION INDICATOR LAMP (MIL) INDICATION (IN RELATION TO READINESS CODES) ).

Manifold Absolute Pressure (MAP) Sensor

The MAP sensor converts manifold absolute pressure into electrical signals to the ECM/PCM.

Scheme 28

Output Shaft (Countershaft) Speed Sensor

This sensor detects countershaft speed.

Scheme 29

Secondary Heated Oxygen Sensor (Secondary HO2S)

The secondary HO2S detects the oxygen content in the exhaust gas downstream of the three way catalytic converter (TWC), and sends signals to the ECM/PCM which varies the duration of fuel injection accordingly. To stabilize its output, the sensor has an internal heater. The ECM/PCM compares the HO2S output with the A/F sensor output to determine catalyst efficiency. The secondary HO2S is located on the TWC.

Scheme 30

Electronic Throttle Control System

The throttle is electronically controlled by the electronic throttle control system. Refer to Electronic Throttle Control System Diagram to see a functional layout of the system.

Idle control: When the engine is idling, the ECM/PCM controls the throttle actuator to maintain the proper idle speed according to engine loads.

Acceleration control: When the accelerator pedal is pressed, the ECM/PCM opens the throttle valve depending on the accelerator pedal position (APP) sensor signal.

Cruise control: The ECM/PCM controls the throttle actuator to maintain set speed when the cruise control is operating. The throttle actuator takes the place of the cruise control actuator.

Accelerator Pedal Position (APP) Sensor

As the accelerator pedal position changes, the sensor varies the signal voltage to the ECM/PCM.

Scheme 31

Throttle Body

The throttle body is a single-barrel side draft type. The lower portion of the throttle valve is heated by engine coolant from the cylinder head to prevent icing of the throttle plate.

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1. The i-VTEC has a VTC (variable valve timing control) mechanism on the intake camshaft in addition to the usual VTEC. This mechanism improves fuel efficiency and reduces exhaust emissions at all levels of engine speed, vehicle speed, and engine load.
2. The VTEC mechanism changes the valve lift and timing by using more than one cam profile.
3. The VTC changes the phase of the intake camshaft via oil pressure. It changes the intake valve timing continuously.

DRIVING CONDITION

Scheme 34

1. The VTC system makes continuous intake valve timing changes based on operating conditions.
2. Intake valve timing is optimized to allow the engine to produce maximum power.
3. Cam angle is advanced to obtain the EGR effect and reduce pumping loss. The intake valve is closed quickly to reduce the entry of the air/fuel mixture into the intake port and improve the charging effect.
4. The system reduces the cam advance at idle, stabilizes combustion, and reduces engine speed.
5. If a malfunction occurs, the VTC system control is disabled and the valve timing is fixed at the fully retarded position.

Scheme 35

1. The VTEC system changes the cam profile to correspond to the engine speed. It maximizes torque at low engine speed and output at high engine speed.
2. The low lift cam is used at low engine speeds, and the high lift cam is used at high engine speeds.

Scheme 36

Camshaft Position (CMP) Sensor A

CMP sensor A detects camshaft angle position for the VTC system.

Scheme 37

Idle Control System

When the engine is cold, the A/C compressor is on, the transmission is in gear, the brake pedal is pressed, the power steering load is high, or the alternator is charging, the ECM/PCM sends signals to the throttle position to maintain the correct idle speed.

Brake Pedal Position Switch

The brake pedal position switch signals the ECM/PCM when the brake pedal is pressed.

Power Steering Pressure (PSP) Switch

The PSP switch signals the ECM/PCM when the power steering load is high.

Fuel Cutoff Control

During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at engine speeds over 1,010 rpm (A/T: 1,042 rpm). Fuel cutoff control also occurs when the engine speed exceeds 7,300 rpm, regardless of the position of the throttle valve, to protect the engine from over-revving. When the vehicle is stopped, the ECM/PCM cuts the fuel at engine speeds over 7,300 rpm (A/T: 5,000 rpm). On a cold engine, fuel cut occurs at a lower engine speed.

Fuel Pump Control

When the ignition is turned on, the ECM/PCM grounds PGM-FI main relay 2 (FUEL PUMP) which feeds current to the fuel pump for 2 seconds to pressurize the fuel system. With the engine running, the ECM/PCM grounds PGM-FI main relay 2 (FUEL PUMP) and feeds current to the fuel pump. When the engine is not running and the ignition is on, the ECM/PCM cuts ground to PGM-FI main relay 2 (FUEL PUMP) which cuts current to the fuel pump.

PGM-FI Main Relay 1 and 2

PGM-FI main relay 1 (Fl MAIN) is energized whenever the ignition switch is ON (II) to supply battery voltage to the ECM/PCM, power to the injectors, and power for PGM-FI main relay 2 (FUEL PUMP). PGM-FI main relay 2 (FUEL PUMP) is energized to supply power to the fuel pump for 2 seconds when the ignition switch is turned ON (II), and when the engine is cranking or running.

Intake Air System

This system supplies air for engine needs.

Intake Air Bypass Control Thermal Valve

When the engine is cold, the intake air bypass control thermal valve sends air to the injector.

The amount of air is regulated by engine coolant temperature. Once the engine is hot, the intake air bypass control thermal valve closes, stopping air to the injector.

Scheme 38

Resonator

A resonator in the intake air duct provides additional silencing as air is drawn into the engine.

Three Way Catalytic Converter (TWC)

The TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to carbon dioxide (CO 2 ), nitrogen (N2), and water vapor.

Scheme 39

Positive Crankcase Ventilation (PCV) System

The PCV valve prevents blow-by gasses from escaping into the atmosphere by venting them into the intake manifold.

Scheme 40

Evaporative Emission (EVAP) Control System

Refer to Evaporative Emission (EVAP) Control Diagram to see the functional layout of the system.

EVAP Canister

The EVAP canister temporarily stores fuel vapor from the fuel tank until it can be purged from the EVAP canister into the engine and burned.

EVAP Canister Purge Valve

When the engine coolant temperature is below 131°F (55°C), the ECM/PCM turns off the EVAP canister purge valve which cuts vacuum to the EVAP canister.

Fuel Tank Pressure (FTP) Sensor

The FTP sensor converts fuel tank absolute pressure into an electrical input to the ECM/PCM.

Scheme 41

EVAP Canister Vent Shut Valve

The EVAP canister vent shut valve is on the EVAP canister.

The EVAP canister vent shut valve controls the venting of the EVAP canister.

Scheme 42

Fuel Cap Warning Message ('06-08 models)

The ECM/PCM detects a loose or missing fuel fill cap as an evaporative system leak and alerts the driver by showing a warning message in the multi-information display.

First drive cycle

The first time a leak is detected a "TIGHTEN FUEL CAP" message appears in the multi-information display (A). To scroll to another message, press the select/reset button. The "TIGHTEN FUEL CAP" message will appear each time you restart the engine until the system turns the message off. Turn the engine off then replace or tighten the fuel fill cap until it clicks at least once.

Scheme 43

Procedure

1. Tighten the fuel fill cap until it clicks.
2. Clear the Temporary DTC with the HDS.
3. Verify there is no leak by doing the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.

1. Tighten the fuel fill cap until it clicks.
2. The message should go off after several days of normal driving.

1. Tighten the fuel fill cap until it clicks.
2. Turn the ignition switch ON (II), and then to LOCK (0).
3. Do step 2 above two more times.

Electronic Throttle Control System Diagram

The electronic throttle control system consists of the throttle actuator, the throttle position (TP) sensor A/B, the accelerator pedal position (APP) sensor A/B, the throttle actuator control module, and the ECM/PCM. The throttle is electronically controlled by this system.

Scheme 44

Evaporative Emission (EVAP) Control Diagram

The EVAP controls minimize the amount of fuel vapor escaping to the atmosphere. Vapor from the fuel tank is temporarily stored in the EVAP canister until it can be purged from the canister into the engine and burned.

The EVAP canister is purged by drawing fresh air through it and into a port on the intake manifold.

The purging vacuum is controlled by the EVAP canister purge valve, which operates whenever engine coolant temperature is above 131°F (55°C).

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Scheme 56

Scheme 57

The vehicle has certain "readiness codes" that are part of the on-board diagnostics for the emissions systems. If the vehicle's battery has been disconnected or gone dead, if the DTCs have been cleared, or if the ECM/PCM has been reset, these readiness codes are reset to incomplete. In some states, part of the emissions testing is to make sure these codes are set to complete. If all of them are not set to complete, the vehicle may fail the emission test, or the test cannot be finished.

To check if the readiness codes are set to complete, turn the ignition switch ON (II), but do not start the engine. The MIL will come on for 15-20 seconds. If it then goes off, the readiness codes are complete. If it flashes five times, one or more readiness codes are not set to complete. To set readiness codes from incomplete to complete, do the procedure for the appropriate code.

To check the status of a specific DTC system, check the OBD status in the DTC MENU with the HDS (see OBD STATUS ). This screen displays the code, the current data list of the enable criteria, and the status of the readiness testing.

Catalytic Converter Monitor and Readiness Code

Note. Do not turn the ignition switch off during the procedure. All readiness codes are cleared when the battery is disconnected, if the DTCs have been cleared, or if the ECM/PCM is reset with the HDS. Low ambient temperatures or excessive stop-and-go traffic may increase the drive time needed to switch the readiness code from incomplete to complete. The readiness code will not switch to complete until all the enable criteria are met. If a fault in the secondary HO2S system caused the MIL to come on, the readiness code cannot be set to complete until you correct the fault.

Enable Criteria

1. ECT SENSOR ('04-05 models), ECT SENSOR 1 ('06-08 models) at 158°F (70°C) or more.
2. Intake air temperature (IAT) at 20°F (-7°C) or more.
3. Vehicle speed sensor (VSS) above 25 mph (40 km/h).

1. Connect the HDS to the vehicle's data link connector (DLC), and bring up the READINESS CODEs screen for Catalyst in the DTCs MENU.
2. Start the engine.
3. Test-drive the vehicle under stop-and-go conditions with short periods of steady cruise. After about 5 miles (8 km), the readiness code should switch to complete.
4. If the readiness code is still not set to complete, check for a Temporary DTC with the HDS. If there is no DTC, one or more of the enable criteria were probably not met; repeat the procedure.

Evaporative Emission (EVAP) Control System Monitor and Readiness Code

Note. All readiness codes are cleared when the battery is disconnected, if the DTCs have been cleared, or if the ECM/PCM is reset with the HDS.

1. Battery voltage is more than 10.5 V.
2. Engine at idle.
3. ECT SENSOR ('04-05 models), ECT SENSOR 1 ('06-08 models) between 176°F (80°C) and 212°F (100°C).
4. MAP SENSOR less than 46.6 kPa (14 in.Hg, 350 mmHg).
5. Vehicle speed 0 mph (0 km/h).
6. IAT SENSOR between 32°F (0°C) and 212°F (100°C).

1. Connect the HDS to the vehicle's data link connector (DLC).
2. Start the engine.
3. Select EVAP TEST in the INSPECTION MENU with the HDS, then select the FUNCTION TEST in the EVAP TEST MENU. If the result is normal, readiness is complete. If the result is not normal, go to the next step.
4. Check for a Temporary DTC. If there is no DTC, one or more of the enable criteria were probably not met; repeat the procedure.

Air Fuel Ratio (A/F) Sensor Monitor and Readiness Code

Note. Do not turn the ignition switch off during the procedure. All readiness codes are cleared when the battery is disconnected, if the DTCs have been cleared, or if the ECM/PCM is reset with the HDS.

ECT SENSOR ('04-05 models), ECT SENSOR 1 ('06-08 models) at 140°F (60°C) or more.

1. Start the engine.
2. Test-drive the vehicle under stop-and-go conditions with short periods of steady cruise. During the drive, decelerate (with the throttle fully closed) for 5 seconds. After about 3.5 miles (5.6 km), the readiness code should switch from incomplete to complete.
3. Check the readiness codes screen for the air fuel ratio (A/F) sensor in the DTCs MENU with the HDS. If the screen shows complete, readiness is complete. If the screen shows not complete, go to the next step.
4. Check for a temporary DTC. If there is no DTC, the enable criteria was probably not met. Select the DATA LIST. Check the ECT SENSOR ('04-05 models), ECT SENSOR 1 ('06-08 models) in the ALL DATA LIST with the HDS. If the ECT SENSOR ('04-05 models), ECT SENSOR 1 ('06-08 models) is less than 140°F (60°C), run the engine until it is more than 140°F (60°C), then repeat the procedure.

Air Fuel Ratio (A/F) Sensor Heater Monitor Readiness Code

Note. All readiness codes are cleared when the battery is disconnected, if the DTCs have been cleared, or if the ECM/PCM is reset with the HDS.

1. Start the engine, and let it idle for 1 minute. The readiness code should switch from incomplete to complete.
2. If the readiness code is still not set to complete, check for a Temporary DTC. If there is no DTC, repeat the procedure.

Misfire Monitor and Readiness Code

1. This readiness code is always set to available because misfiring is continuously monitored.
2. Monitoring pauses, and the misfire counter resets, if the vehicle is driven over a rough road.
3. Monitoring also pauses, and the misfire counter holds at its current value, if the throttle position changes more than a predetermined value, or if driving conditions fall outside the range of any related enable criteria.

Fuel System Monitor and Readiness Code

1. This readiness code is always set to available because the fuel system is continuously monitored during closed loop operation.
2. Monitoring pauses when the catalytic converter, EVAP control system, and A/F sensor monitors are active.
3. Monitoring also pauses when any related enable criteria are not being met. Monitoring resumes when the enable criteria is again being met.

Comprehensive Component Monitor and Readiness Code

This readiness code is always set to available because the comprehensive component monitor is continuously running whenever the engine is cranking or running.

See also:
• DLC CIRCUIT TROUBLESHOOTING
• '07-08 MODELS
• MIL CIRCUIT TROUBLESHOOTING
• ECM/PCM IDLE LEARN PROCEDURE
• THROTTLE BODY CLEANING
• P0010
• P0011
• P0107
• P0108
• P0111
• P0112
• P0113
• P0116
• P0116
• P0117
• P0118
• P0122
• P0123
• P0125
• P0125
• P0128
• P0128
• P0133
• P0134
• P0135
• P0137
• P0138
• P0139
• P0141
• P0171
• P0222
• P0223
• P0300
• P0301
• P0325
• P0335
• P0339
• P0340
• P0341
• P0344
• P0365
• P0369
• P0420
• P0442
• P0443
• P0451
• P0452
• P0453
• P0461
• P0462
• P0463
• P0498
• P0499
• P0506
• P0562
• P0563
• P0602
• P0603
• P0606
• P062F
• P0630
• P0685
• P0700
• P0720
• P1009
• P1109
• P1116
• P1128
• P1129
• P1157
• P1172
• P1297
• P1298
• P1454
• P1549
• P1683
• P1684
• P16BB
• P16BC
• P2101
• P2108
• P2118
• P2122
• P2123
• P2127
• P2128
• P2135
• P2138
• P2176
• P2183
• P2184
• P2185
• P2195
• P2227
• P2228
• P2229
• P2238
• P2252
• P2270
• P2279
• P2552
• P2610
• P2646
• P2647
• P2648
• P2649
• P2A00
• U0073
• U0073
• U0107
• U0122
• U0155
• BATTERY TEST
• STARTER PERFORMANCE TEST
• FUEL PRESSURE TEST
• FUEL PUMP CIRCUIT TROUBLESHOOTING
• TROUBLESHOOTING
• IDLE SPEED INSPECTION
• THROTTLE CABLE ADJUSTMENT
• THROTTLE POSITION LEARNING CHECK
• APP SENSOR SIGNAL INSPECTION
• PSP SWITCH SIGNAL CIRCUIT TROUBLESHOOTING
• FUEL TANK REPLACEMENT
• MALFUNCTION INDICATOR LAMP (MIL) INDICATION (IN RELATION TO READINESS CODES)
• CATALYTIC CONVERTER MONITOR AND READINESS CODE
• Electronic Throttle Control System Diagram
• Evaporative Emission (EVAP) Control Diagram
• OBD STATUS