Fuel and Emissions Systems Acura RDX I

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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 pins at all connectors related to the circuit that you are troubleshooting. If the MIL was on but then went out, the original problem may have been intermittent.

Service Information

Some DTCs or symptoms can be caused by a combination of PCM software and specific driving habits. Periodically, new 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 PCMs) this can sometimes mean something works, but not the way it's supposed to.

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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 stays on for 15-20 seconds (see «HOW TO SET READINESS CODES»(/acura/rdx/i-2006-2009/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 PCM and other vehicle systems. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/rdx/i-2006-2009/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ).
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 powertrain control module (PCM) data. For specific operations, refer to the that came with the HDS.
6. If no DTCs are found, go to MIL troubleshooting (see «MIL CIRCUIT TROUBLESHOOTING»(/acura/rdx/i-2006-2009/remont/testing-diagnostics/#pgm-fi-system) ).

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 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 PCM.

HDS Clear Command

The 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. 19 Fl MAIN (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, PCM reset, and crank (CKP) pattern clear. DTC clear command erases all stored DTC codes, freeze data, on-board snapshot, and readiness codes. This must be done with the HDS after reproducing the DTC during troubleshooting. The PCM reset command erases all stored DTC codes, freeze data, on-board snapshot, readiness codes, and all specific data to correct the system except crank (CKP) pattern. If the crank (CKP) pattern data in the PCM was cleared, you must do the crank (CKP) pattern learn procedure. The crank (CKP) pattern clear command erases only crank (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 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: PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ); crank (CKP) pattern learn procedure; test-drive to set readiness codes to complete (see HOW TO SET READINESS CODES ).

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.

PCM Reset

1. Reset the 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 PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/rdx/i-2006-2009/remont/engine-control-systems/#idle-control-system__pcm-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 PCM. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/rdx/i-2006-2009/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ).
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 transmission in S position 1st or 2nd gear.
3. Repeat step 2 several times.
4. Turn the ignition switch OFF.
5. Turn the ignition switch ON (II), and wait 30 seconds.

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

1. Reset the PCM with the HDS.
2. Do the PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/rdx/i-2006-2009/remont/engine-control-systems/#idle-control-system__pcm-idle-learn-procedure) ).
3. Turn the ignition switch OFF.
4. Disconnect the HDS from the DLC.

Note. The PCM is part of the immobilizer system. If you replace the 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 PCM Connectors

Note. The PCM overwrites data and monitors the EVAP system for up to 30 minutes after the ignition switch is turned OFF. Jumping the SCS line after turning the ignition switch OFF cancels this function. Disconnecting the PCM during this function, without jumping the SCS line first, can damage the PCM.

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1. Jump the SCS line with the HDS.
2. Disconnect the PCM connectors A, B, and C.
3. When diagnosis/troubleshooting is done at the PCM connector, use the terminal test port (A) above the terminal you need to check.
4. Connect one side of the patch cord (A) terminals to a commercially available digital multimeter (B), and connect the other side of the patch cord terminals to a commercially available banana jack (Pomona Electronics Tool No. 3563 or equivalent) (C).
5. Gently contact the pin probe (male) at the terminal test port from the terminal side. Do not force the tips into the terminals.

Note. For accurate results, always use the pin probe (male). To prevent damage to the connector terminals, do not insert test equipment probes, paper clips, or other substitutes as they can damage the terminals. Damaged terminals cause a poor connection and an incorrect measurement. Do not puncture the insulation on a wire. Punctures can cause poor or intermittent electrical connections.

Substituting the 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 PCM during troubleshooting procedures.

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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 to ON (II).
3. Make sure the HDS communicates with the PCM. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/rdx/i-2006-2009/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ). If you are returning from DLC circuit troubleshooting, skip step 4 and 5, and clean the throttle body after substituting the PCM (see «THROTTLE BODY CLEANING»(/acura/rdx/i-2006-2009/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).
4. USA, Canada models: Select the INSPECTION MENU with the HDS.
5. USA, Canada models: 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. Disconnect the PCM connectors A, B, and C. NOTE: PCM connectors A, B, and C have symbols (A=[], B=delta, C=o) embossed on them for identification.
9. Remove the bolts (D), then remove the PCM assembly (E).
10. Remove the cover (A) and the bracket (B) from the PCM (C).
11. Install a known-good PCM in the reverse order of removal.
12. Open the SCS with the HDS.
13. Turn the ignition switch ON (II). NOTE: DTC P0630 "VIN Not Programmed or Mismatch" may be stored because the VIN has not been programmed into the PCM; ignore it, and continue this procedure.
14. Manually input the VIN to the PCM with the HDS.
15. Update the PCM if it does not have the latest software.
16. Select the IMMOBI SYSTEM with the HDS.
17. Enter the immobilizer code using the PCM replacement procedure in the HDS; this allows you to start the engine.
18. Reset the PCM with the HDS.
19. USA, Canada models: If the TP POSITION CHECK failed in step 5, clean the throttle body (see «AIR CLEANER REMOVAL/INSTALLATION»(/acura/rdx/i-2006-2009/remont/mechanical/#intake-air-system) ).
20. Do the PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/rdx/i-2006-2009/remont/engine-control-systems/#idle-control-system__pcm-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 DIAGNOSTIC TROUBLE CODE CHART

DTC DIAGNOSTIC TROUBLE CODE CHART

DTC Troubleshooting Index

DTC DIAGNOSTIC TROUBLE CODE CHART

DTC DIAGNOSTIC TROUBLE CODE CHART

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.

TROUBLESHOOTING SYMPTOM REFERENCE

Electronic Control System

The functions of the fuel and emission control systems are managed by the powertrain control module (PCM).

Self-diagnosis

The PCM detects a failure of a signal from a sensor or from another control unit and stores a Temporary DTC or a DTC in erasable memory (RAM). Depending on the failure, a DTC is stored in either the first or the second drive cycle (for DTC P0457, the DTC is set in the beginning of the third drive cycle). When a DTC is stored, the PCM turns on the malfunction indicator lamp (MIL) by sending a command to the gauge control module.

1. One Drive Cycle Detection Method When an abnormality occurs in the signal from a sensor or from another control unit, the PCM stores a DTC for the failure in the RAM and turns on the MIL immediately.
2. Two Drive Cycle Detection Method

When an abnormality occurs in the signal from a sensor or from another control unit in the first drive cycle, the PCM stores a Temporary DTC for the failure in RAM. The MIL does not come on at this time. If the failure continues in the second drive cycle, the PCM stores a DTC in erasable memory and turns on the MIL.

Fail-safe Function

When an abnormality occurs in the signal from a sensor or from another control unit, the 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 PCM supplies ground to the MIL 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 PCM stays on (up to 30 minutes). If the PCM connector is disconnected during this time, the 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.

VOLTAGE SPECIFICATION

PCM Inputs and Outputs at Connector A ([]) (44P)

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

Scheme 22

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

PCM Inputs and Outputs at Connector B ( ) (44P)

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

Scheme 23

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

PCM Inputs and Outputs at Connector C (o) (44P)

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

Note. Standard battery voltage is about 12 V.

VOLTAGE SPECIFICATION

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 PCM receives a demand for cooling from the A/C system, it delays the compressor from being energized, and enriches the 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 warm up three way catalytic converter (WU-TWC), and sends signals to the PCM which varies the duration of fuel injection accordingly.

Scheme 24

Barometric Pressure (BARO) Sensor

The BARO sensor is inside the 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 25

Crankshaft Position (CKP) Sensor

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

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Engine Coolant Temperature (ECT) Sensors 1 and 2

ECT sensors 1 and 2 are temperature dependent resistors (thermistors). The resistance decreases as the engine coolant temperature increases. ECT sensor 1 is on the cylinder head, and ECT sensor 2 is on the radiator.

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Ignition Timing Control

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

Injector Timing and Duration

The 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 PCM detects long term malfunctions in the fuel system and sets a diagnostic trouble code (DTC).

Knock Sensor

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

Scheme 29

Manifold Absolute Pressure (MAP) Sensor

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

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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 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 HOW TO SET READINESS CODES ).

Mass Air Flow (MAF) Sensor/Intake Air Temperature (IAT) Sensor 1

The mass air flow (MAF) sensor/intake air temperature (IAT) sensor contains a hot wire and a thermistor. It is located in the intake air passage. The resistance of the hot wire and thermistor change due to intake air flow and air temperature. The control circuit in the MAF sensor controls the current to keep the hot wire at a set temperature. The current is converted to voltage in the control circuit, then output to the PCM.

Scheme 31

Intake Air Temperature (IAT) Sensor 2

IAT sensor 2 is a temperature dependent resistor (thermistor). The resistance of the thermistor decreases as the intake air temperature increases.

Scheme 32

Secondary Heated Oxygen Sensor (Secondary HO2S)

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

Scheme 33

Electronic Throttle Control System

The throttle is electronically controlled by the electronic throttle control system. Refer to the system diagram to see a functional layout of the system.

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

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

Cruise control: The 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 PCM.

Scheme 34

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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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 PCM controls current to the throttle actuator to maintain the correct idle speed.

Brake Pedal Position Switch

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

Power Steering Pressure (PSP) Switch

The PSP switch signals the 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 850 RPM. Fuel cutoff control also occurs when the engine speed exceeds 6,900 RPM, regardless of the position of the throttle valve, to protect the engine from over-revving. When the vehicle is stopped, the PCM cuts the fuel at engine speeds over 5,000 RPM. Engine speed of fuel cut is lower on a cold engine.

Fuel Pump Control

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

PGM-FI Main Relay 1 and 2

PGM-FI main relay 1 is energized whenever the ignition switch is ON (II) to supply battery voltage to the 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 (fuel pump control module) for 2 seconds when the ignition switch is turned ON (II), and when the engine is cranking or running.

Transfer Fuel Pump

The fuel in the right side of the fuel tank is drawn over to the left side by the transfer fuel pump.

VTEC/VTC

1. The i-VTEC has a variable valve timing control (VTC) 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.

Scheme 36

VTC System

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 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 37

VTEC System

1. The VTEC system changes the one side of the intake side 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 by one side of the intake valves at a low engine speed. At high engine speed, both intake valves uses the high lift cam.

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Camshaft Position (CMP) Sensor A

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

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Warm Up Three Way Catalytic Converter (WU-TWC) and Three Way Catalytic Converter (TWC)

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

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Positive Crankcase Ventilation (PCV) System

The PCV valve prevents blow-by gasses from escaping into the atmosphere by venting them into the intake manifold. The PCV valve opens at idle, low load, and decelerating with the throttle valve fully closed.

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Evaporative Emission (EVAP) Control System

Refer to the system 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 back into the engine and burned (refer to the system diagram to see the functional layout of the system).

EVAP Canister Purge Valve

When the engine coolant temperature is below 140°F (60°C), the PCM turns off the EVAP canister purge valve which cuts vacuum to the EVAP canister.

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Fuel Tank Pressure (FTP) Sensor

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

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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.

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Fuel Cap Warning Message

The PCM will detect a loose or missing fuel fill cap as an evaporative system leak and alerts the driver by showing a warning message in the gauge display.

First drive cycle

The first time a leak is detected a "TIGHTEN FUEL CAP" (multi-information display model) ("CHECK FUEL CAP" (information display model)) message in the gauge display (A). To scroll to another message, press the select/reset button. The "TIGHTEN FUEL CAP"/"CHECK 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.

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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. Start the Engine, then turn the ignition switch to LOCK (0).
3. Repeat step 2 two more times.

Electronic Throttle Control System Diagram

The electronic throttle control system consists of the throttle actuator, throttle position (TP) sensor A/B, accelerator pedal position (APP) sensor A/B, the electronic throttle control system (ETCS) control relay, and the PCM.

Scheme 49

Evaporative Emissions (EVAP) Control System Diagram

The EVAP control system minimizes the 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 purge amount and timing is duty controlled by the PCM by operating the EVAP canister purge valve. This system is operated whenever the engine coolant temperature is above 140°F (60°C). For this turbo engine model, there are two different purge flow passages, because the intake manifold pressure can be positive (boost pressure) or negative (vacuum pressure).

Purge to the throttle body

When the engine is under a low load condition, the pressure inside the intake manifold is negative (vacuum pressure). The vacuum pressure of the intake manifold opens non-return valve A and closes non-return valve B. Under this condition, the purge air flows from the EVAP canister through the EVAP canister purge valve and non-return valve A, into the throttle body.

Scheme 50

Purge to the intake air duct (turbocharger inlet pipe)

When the engine load increases, the pressure after the turbocharger changes to positive pressure due to turbocharger operation. The boost pressure at the throttle body closes non-return valve A, and due to the boost pressure at the charge air cooler, some part of the compressed airflows through the passage from the air bypass valve base to the intake air duct (turbocharger inlet pipe). When the speed of that compressed air increases at the EVAP canister purge nozzle, it draws the purge air from the EVAP canister side. The non-return valve B opens by this vacuum pressure, and the purge air flows from the EVAP canister through the EVAP canister purge valve and non-return valve B, into the intake air duct (turbocharger inlet pipe).

Scheme 51

Purge to the both intake air duct (turbocharger inlet pipe) and the throttle body

When the engine is under a mid load condition, the pressure after the turbocharger is positive due to the turbocharger operation, but the pressure at the intake manifold is negative because the throttle valve is nearly closed. Under this condition, both non-return valves A and B open and the purge air flows from the EVAP canister through the EVAP canister purge valve and non-return valves A and B, into the throttle body and the intake air duct (turbocharger inlet pipe).

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Turbocharger Control System

Refer to the system diagram to see a functional layout of the system.

Turbocharger Boost Sensor

This sensor converts charge air cooler pressure into an electrical signal that is received by the PCM.

Scheme 53

Turbocharger Wastegate Control Solenoid Valve

This solenoid valve controls pressure to the turbocharger wastegate control actuator. The solenoid itself is controlled by the PGM. The following information describes the ports on the valve and where the pressure flows when the solenoid switches the valve on and off.

Scheme 54

Turbocharger Bypass Control Solenoid Valve

This solenoid valve controls pressure to the turbocharger bypass control valve. The solenoid itself is controlled by the PCM. The following information describes the ports on the valve and where the pressure flows when the solenoid switches the valve on and off.

Scheme 55

Turbocharger Boost Control Solenoid Valve

This solenoid valve controls pressure to the turbocharger boost control valve. The solenoid itself is controlled by the PCM. The following information describes the ports on the valve and where the pressure flows when the solenoid switches the valve on and off.

Scheme 56

Turbocharger Control System Diagram

The turbocharger control system controls the boost pressure and the response of the turbocharger. The PCM controls the turbocharger wastegate control solenoid valve (duty controlled), the turbocharger bypass control solenoid valve (on/off controlled), and the turbocharger boost control valve (duty controlled). The boost pressure is monitored by the turbocharger boost sensor.

Scheme 57

Turbocharger Wastegate Control System

This system controls the wastegate control solenoid to prevent the turbo from exceeding maximum boost pressure. This system is duty controlled by the PCM. The descriptions A and B are the two conditions of duty. Condition A (maximum duty) and condition B (minimum duty). At other times, the turbocharger wastegate control solenoid controls both the passages from the intake air duct (turbocharger inlet connecting tube), and the intake air duct (turbocharger outlet pipe) to the turbocharger wastegate control actuator.

Condition A (maximum duty)

When the turbocharger boost sensor signal is lower than the upper limit, the PCM turns on (maximum duty) the turbocharger wastegate control solenoid valve, and opens the passage between the intake air duct (turbocharger inlet connecting tube) and the turbocharger wastegate control actuator and closes the passage from the intake air duct (turbocharger outlet pipe) and the turbocharger wastegate control actuator. The pressure at the turbocharger wastegate control actuator is released to the intake air duct (turbocharger inlet connecting tube), and the spring in the turbocharger wastegate control actuator closes the turbocharger wastegate control valve. In this condition, all of the exhaust gas flows to the turbine. This increases the RPM of the turbine, increasing boost pressure.

Scheme 58

Condition B (minimum duty)

When the turbocharger boost sensor signal reaches the upper limit, the PCM turns off (minimum duty) the turbocharger wastegate control solenoid valve, and opens the passage between the intake air duct (turbocharger outlet pipe) and the turbocharger wastegate control actuator and closes the passage from the intake air duct (turbocharger inlet connecting tube) and the turbocharger wastegate control actuator. The boost pressure from the intake air duct (turbocharger outlet pipe) pushes the turbocharger wastegate control actuator and opens the turbocharger wastegate control valve. In this condition, only a portion of the exhaust gas flows through the bypass passage bypassing the turbocharger wastegate control valve, and the amount of exhaust gas to the turbocharger decreases. This decreases the RPM of the turbine decreasing boost pressure.

Scheme 59

Turbocharger Bypass Control System

This system improves the boost response of acceleration immediately after deceleration. This system also, protects the turbocharger from the negative effects of compressor surge during high boost. The descriptions A and Bare the two conditions of the turbocharger bypass control solenoid valve on and off. Condition A (on) and condition B (off).

Condition A (Solenoid Valve ON)

When the vehicle is in cruise or accelerating, the PCM turns on the turbocharger bypass control solenoid valve, and opens the passage between the charge air cooler and the turbocharger bypass control valve and closes the passage between the intake manifold and the turbocharger bypass control valve. The boost pressure from the charge air cooler pushes the turbocharger bypass control valve, and closes the passage between the charge air cooler and the intake air duct (turbocharger inlet pipe). By doing this, all compressed air is routed to the intake manifold.

Scheme 60

Condition B (Solenoid Valve OFF)

During the deceleration with the throttle valve closed, the PCM turns off the turbocharger bypass control solenoid valve and opens the passage between the intake manifold and the turbocharger bypass control valve and closes the passage between the charge air cooler and the turbocharger bypass control valve. The vacuum pressure from the intake manifold pulls the turbocharger bypass control valve and opens the passage between the charge air cooler and the intake air duct (turbocharger inlet pipe). By doing this, the compressed air flows from the charge air cooler to the intake air duct (turbocharger inlet pipe) to keep the turbine spinning. This improves the acceleration response of the turbocharger after deceleration.

Scheme 61

Turbocharger Boost Control System

This system controls the exhaust gas passage to the turbine by changing the variable flap angle. The variable flap is moved by the turbocharger boost control actuator, and it is duty controlled by the PCM depending on the driving condition.

Scheme 62

When the variable flap is fully closed, all exhaust gas flows to the inner scroll of the turbocharger. Under this condition, the exhaust gas speed is accelerated, and the turbocharger response is improved. When the variable flap is fully opened, the exhaust gas flows through both the outer and the inner scroll of the turbocharger. Under this condition, the exhaust gas is efficiently used to improve the maximum boost. Because of this system, the turbocharger functions both as a quick responding small size turbocharger, and high capacity turbocharger.

The description A and B are the two conditions of duty. Condition A (maximum duty) and condition B (minimum duty). At other times, the turbocharger boost controls both the passages from the intake air duct (turbocharger inlet connecting tube), and the intake air duct (turbocharger outlet pipe) to the turbocharger boost control actuator.

Under a low engine speed/low load condition (with only a small amount of exhaust gas), the PCM turns on (maximum duty) the turbocharger boost control solenoid valve and opens the passage between the intake air duct (turbocharger inlet connecting tube) and the turbocharger boost control actuator and closes the passage between the intake air duct (turbocharger outlet pipe) and the turbocharger boost control actuator. The pressure at the turbocharger boost control actuator is released to the intake air duct (turbocharger inlet connecting tube), and the spring inside the turbocharger boost control actuator closes the variable flap. With the variable flap closed, the exhaust gas flows at high speed through the inner scroll of the turbocharger improving the turbo response.

Scheme 63

Under a mid or high load conditions (with large amount of exhaust gas), the PCM turns off (minimum duty) the turbocharger boost control solenoid valve and opens the passage between the intake air duct (turbocharger outlet pipe) and the turbocharger boost control actuator and closes the passage between the intake air duct (turbocharger inlet connecting tube) and the turbocharger boost control actuator. The boost pressure from intake air duct (turbocharger outlet pipe) pushes the turbocharger boost control actuator which opens the variable flap. With the variable flap opened, the exhaust gas flows through both the inner and the outer scroll for efficient turbo operation at mid and high engine speed.

Scheme 64

Scheme 65

Scheme 66

Scheme 67

Scheme 68

Scheme 69

Scheme 70

Scheme 71

PCM Circuit Diagram (7 Of 14). Scheme 72

Scheme 73

Scheme 74

Scheme 75

PCM Circuit Diagram (11 Of 14). Scheme 76

PCM Circuit Diagram (12 Of 14). Scheme 77

Scheme 78

Scheme 79

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 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 set to 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 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 1 at 158°F (70°C) or more.
2. IAT SENSOR 1 at 20°F (-7°C) or more.
3. 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 PCM is reset with the HDS.

1. Battery voltage is more than 10.5 V.
2. Engine at idle.
3. ECT SENSOR 1 and 2 between 176°F (80°C) and 212°F (100°C).
4. VSS 0 mph (0 km/h).
5. IAT SENSOR 1 between 32°F (0°C) and 212°F (100°C).

1. Connect the HDS to the 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 PCM is reset with the HDS.

ECT SENSOR 1 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 MENU. Check the ECT SENSOR 1 in the ALL DATA LIST with the HDS. If ECT SENSOR 1 is less than 140°F (60°C), run the engine until it is more than 140°F (601), 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 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
• MIL CIRCUIT TROUBLESHOOTING
• PCM IDLE LEARN PROCEDURE
• THROTTLE BODY CLEANING
• AIR CLEANER REMOVAL/INSTALLATION
• P0010
• P0011
• P0034
• P0035
• P0045
• P0096
• P0097
• P0098
• P0101
• P0102
• P0103
• P0107
• P0108
• P0112
• P0113
• P0116
• P0117
• P0118
• P0122
• P0123
• P0125
• P0128
• P0133
• P0134
• P0135
• P0137
• P0138
• P0139
• P0141
• P0171
• P0222
• P0223
• P0234
• P0236
• P0237
• P0238
• P0243
• P0299
• P0300
• P0301
• P0325
• P0335
• P0339
• P0340
• P0341
• P0344
• P0365
• P0369
• P0420
• P0443
• P0451
• P0452
• P0453
• P0455
• P0461
• P0462
• P0463
• P0498
• P0499
• P0506
• P050A
• P050B
• P0532
• P0533
• P0562
• P0563
• P0602
• P0606
• P060A
• P0627
• P062F
• P0630
• P0685
• P0720
• P1009
• P1109
• P1116
• P1128
• P1129
• P1157
• P1172
• P1233
• P1297
• P1298
• P1454
• P1549
• P1658
• P1683
• P1684
• P16BB
• P16BC
• P2118
• P2122
• P2123
• P2127
• P2128
• P2135
• P2138
• P2176
• P2183
• P2184
• P2185
• P2195
• P2199
• P2227
• P2228
• P2229
• P2238
• P2252
• P2261
• P2263
• P2270
• P2610
• P2646
• P2647
• P2648
• P2649
• P2A00
• U0028
• U0114
• U0122
• U0155
• BATTERY TEST
• STARTER PERFORMANCE TEST
• FUEL PRESSURE TEST
• IDLE SPEED INSPECTION
• THROTTLE POSITION LEARNING CHECK
• CARBON ACCUMULATION CHECK
• APP SENSOR SIGNAL INSPECTION
• TURBOCHARGER WASTEGATE CONTROL SOLENOID VALVE INSPECTION
• TURBOCHARGER BOOST CONTROL SOLENOID VALVE INSPECTION
• TURBOCHARGER BYPASS CONTROL SOLENOID VALVE INSPECTION
• TURBOCHARGER BYPASS CONTROL VALVE REPLACEMENT
• FUEL TANK UNIT REMOVAL AND INSTALLATION
• FUEL TANK REPLACEMENT
• FUEL CAP WARNING MESSAGE SYSTEM TROUBLESHOOTING
• HOW TO SET READINESS CODES
• TURBOCHARGER CONTROL SYSTEM DIAGRAM
• OBD STATUS