Fuel and Emissions Systems Acura MDX 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.

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.

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 stays on for 15-20 seconds (see «HOW TO SET READINESS CODES»(/acura/mdx/i-2000-2006/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. 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 DTC's 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 user's manual that came with the HDS.
5. If no DTCs are found, go to MIL troubleshooting (see «MIL CIRCUIT TROUBLESHOOTING»(/acura/mdx/i-2000-2006/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. 10 BACK UP (7.5 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 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 CKP pattern. If the CKP pattern data in the PCM was cleared, you must do the CKP pattern learn procedure. The 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 PCM, and it clears all commands at the same time (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 ); 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

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

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/mdx/i-2000-2006/remont/testing-diagnostics/#idle-control-system__pcm-idle-learn-procedure) ).

CKP Pattern Clear/CKP Pattern Learn

Note. The ECT needs to be at 176°F (80°C) or higher. Before doing this procedure, check "PULSER F/B LEARN" and "PULSER F/B LEARN (HIGH RPM)" in the DATA LIST with the HDS. If both values show N/A, this procedure is not needed. Go back to the troubleshooting or other procedures you were doing. If only "PULSER F/B LEARN (HIGH RPM)" shows N/A, skip steps 4 through 9 .

1. Clear the CKP pattern while the engine is stopped.
2. Turn the ignition switch OFF.
3. Turn the ignition switch ON (II), and wait 30 seconds.
4. Test-drive the vehicle on a level road: decelerate (with the throttle fully closed) from an engine speed of 2,500 rpm to 1,000 rpm with the transmission in 2 position.
5. Stop the vehicle, but keep the engine running.
6. Check PULSER F/B LEARN in the DATA LIST with the HDS. If it is NOT COMPLETED, go to step 4 . If it is COMPLETED, go to step 7.
7. Test-drive the vehicle on a level road: decelerate (with the throttle fully closed) from an engine speed of 5,000 rpm to 3,000 rpm with the transmission in 2 position.
8. Stop the vehicle, but keep the engine running.
9. Check the PULSER F/B LEARN (HIGH RPM) in the DATA LIST with the HDS. If it is NOT COMPLETED, go to step 7 . If it is COMPLETED, go to step 10.
10. Turn the ignition switch OFF.
11. Turn the ignition switch ON (II), and wait 30 seconds. The CKP learning procedure is completed.

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/mdx/i-2000-2006/remont/testing-diagnostics/#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

Special Tools Required

1. Digital multimeter KS-AHM-32-003 (1) or a commercially available digital multimeter
2. Connector test adapter Kit J35616-A
3. Pin probe (male) 07ZAJ-RDJA110
4. Flat spade probe (male) 07ZAJ-RDJA120

Note. The PCM overwrites data and monitors the EVAP system for up to 15 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. With the ignition switch ON (II), connect the HDS to the data link connector (DLC), and go into any of the live data screens.
2. Turn the ignition switch OFF.
3. Exit and then restart the HDS software. Go to the SCS mode and follow the screens to ground the 16PDLC. NOTE: Steps 1 through 3 must be done to protect the powertrain control module (PCM) from damage, or wait at least 15 minutes before disconnecting.
4. Disconnect the PCM connectors and probe the terminals from the terminal side of the connectors.
5. Make sure the connector terminals diameter and select the suitable pin probe (male) and/or flat spade probe (male).
6. Connect one side of the patch cord (A) terminals to the digital multimeter (B), and connect the other side of the patch cord terminals to the pin probe (male) and/or flat spade probe (male) (C).
7. Gently slide the pin probe (male) into the connector terminals 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 the 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.

PCM Updating and Substitution for Testing

Special Tools Required

Honda interface module (HIM) EQS05A35570

Use this procedure when you have to substitute a known-good PCM in a troubleshooting procedure. Update the PCM only if the PCM does not have the latest software loaded.

Note. Do not turn the ignition switch OFF while updating the PCM. If you turn the ignition switch OFF before completion, the PCM can be damaged.

How to Update the PCM

Note. To ensure the latest program is installed, do a PCM update whenever the PCM is substituted or replaced. You can not update a PCM with the program it already has. It will only accept a new program. Before you update the PCM, make sure the vehicle's battery is fully charged. To prevent PCM damage, do not operate anything electrical (audio system, brakes, A/C, power windows, moonroof, door locks, etc.) during the update. If you need to diagnose the Honda interface module (HIM) because the HIM's red (# 3) light came on or was flashing during the update, leave the ignition switch in the ON (II) position when you disconnect the HIM from the data link connector (DLC). This will prevent PCM damage. High temperature in the engine compartment might cause the PCM to become too hot to run the update. If the engine has been running before this procedure, open the hood and cool the engine compartment.

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1. Turn the ignition switch ON (II). 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. Select the INSPECTION MENU with the HDS.
4. Do the TP POSITION CHECK in the ETCS TEST.
5. If the HDS does not have the update function, disconnect the HDS from the vehicle and connect the Honda interface module (HIM).
6. If the software in the PCM is the latest, disconnect the HDS or the HIM from the DLC, and go back to the procedure that you were doing. If the software in the PCM is not the latest, do the PCM update procedure as described on the HIM label or in the PCM update system. NOTE: If the PCM update system requires you to cool the PCM, follow what is shown in the screen.
7. Do the PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/mdx/i-2000-2006/remont/testing-diagnostics/#idle-control-system__pcm-idle-learn-procedure) ).
8. Do the CKP pattern clear/pattern learn procedure.

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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. Make sure the HDS communicates with the PCM. If it doesn't, skip steps 3 to 5 and clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/mdx/i-2000-2006/remont/testing-diagnostics/#intake-air-system__throttle-body-cleaning) ) after this procedure.
3. Turn the ignition switch ON (II).
4. Select the INSPECTION MENU with the HDS.
5. Do the TP POSITION CHECK in the ETCS TEST.
6. Turn the ignition switch OFF.
7. Jump the SCS line with the HDS.
8. Remove the cover (A).
9. Disconnect the PCM connectors (B).
10. Remove the bolts (C), then remove the PCM (D).
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: For 2005-2006 models: 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. Input the VIN to the PCM with the HDS.
15. Rewrite the immobilizer code with the PCM replacement procedure in the HDS; it allows you to start the engine.
16. Reset the PCM with the HDS.
17. Do the PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/mdx/i-2000-2006/remont/testing-diagnostics/#idle-control-system__pcm-idle-learn-procedure) ).
18. Do the CKP pattern clear/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 technician's repair was successfully finished. The results of diagnostic tests for the DTC are displayed as

1. PASSED: On board diagnosis is successfully finished.
2. FAILED: 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

Note. The following DTCs are indicated when the PGM-FI system is selected in the HDS. Some automatic transmission DTCs cause the MIL to come on. If the MIL is on and no DTCs are indicated in the PGM-FI system, select the A/T system and check automatic transmission DTCs.

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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 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 the first or second drive cycle. When a DTC is stored, the PCM turns on the malfunction indicator lamp (MIL) by supplying ground to the MIL circuit.

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 indicates 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. The MIL does not come on. If the failure continues in the second drive cycle, the PCM stores a DTC 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 assumes a pre-programmed value 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 first turned ON (II), the PCM supplies ground to the MIL circuit for 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 out.

Self Shut Down (SSD) Mode

After the ignition switch is turned OFF, the PCM stays on for up to 15 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 turning the ignition switch OFF.

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PGM-FI System

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

Alternator Control

The alternator signals the PCM during charging.

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 WU-TWC, and sends signals to the PCM which varies the duration of fuel injection accordingly.

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Barometric Pressure (BARO) Sensor

The BARO sensor is inside the PCM. It converts atmospheric pressure into a voltage signal that is used by the PCM to modify the basic duration of the fuel injection discharge.

Camshaft Position (CMP) Sensor

The CMP sensor input is used by the PCM to determine ignition timing at start up (cranking) and when crank angle is abnormal.

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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) Sensor

The ECT sensor is a temperature dependent resistor (thermistor). The resistance of the thermistor decreases as the engine coolant temperature increases.

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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.

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).

Intake Air Temperature (IAT) Sensor 1/Intake Air Temperature (IAT) Sensor 2 (2003-2004 models) Intake Air Temperature (IAT) Sensor (2005-2006 models)

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

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Knock Sensor

The knock control system adjusts the ignition timing to minimize knock using signals from the knock sensor (KS).

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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 set to complete. To set each code, drive the vehicle or run the engine as described in the procedures (see HOW TO SET READINESS CODES ).

Manifold Absolute Pressure (MAP) Sensor

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

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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. 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 on the WU-TWC.

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Electronic Throttle Control System

The throttle is electronically controlled by the electronic throttle control system. Refer to the ELECTRONIC THROTTLE CONTROL SYSTEM DIAGRAM to see the 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.

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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 Cut-off Control

During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at engine speeds over 950 rpm. Fuel cut-off control also occurs when the engine speed exceeds 6,500 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. On a cold engine, fuel cut occurs at a lower engine speed.

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 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. 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.

PGM-FI Main Relay 1 and 2

PGM-FI main relay 1 (FI MAIN) 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 for 2 seconds when the ignition switch is turned ON (II), and when the engine is cranking or running.

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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Exhaust Gas Recirculation (EGR) System

Refer to the EXHAUST GAS RECIRCULATION (EGR) SYSTEM DIAGRAM to see a functional layout of the system.

EGR Valve

The EGR valve lowers peak combustion temperatures and reduces oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the intake manifold and into the combustion chambers.

Positive Crankcase Ventilation (PCV) System

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

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Evaporative Emission (EVAP) Control System

Refer to the EVAPORATIVE EMISSION (EVAP) CONTROL DIAGRAM to see a 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 149°F (65°C), the 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 PCM during the EVAP leak check.

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EVAP Canister Vent Shut Valve

The EVAP canister vent shut valve is in the EVAP drain module (2003-2004 models).

The EVAP canister vent shut valve is on the EVAP canister (2005-2006 models).

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

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EVAP Two Way Valve and EVAP Bypass Solenoid Valve (2003-2004 models)

The EVAP two way valve is installed between the fuel tank and the EVAP canister.

The EVAP two way valve sends fuel vapor to the EVAP canister corresponding to the pressure inside the fuel tank and prevents excessive vacuum in the fuel tank by drawing in fresh air through the EVAP canister. The EVAP bypass solenoid valve opens to bypass the two way valve when doing the EVAP leak check.

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Electronic Throttle Control System Diagram

The Electronic Throttle Control System consists of the throttle actuator, throttle actuator control module, throttle actuator control relay, throttle position (TP) sensors, accelerator pedal position (APP) sensor, and the PCM. The throttle is electronically controlled by this system.

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Exhaust Gas Recirculation (EGR) System Diagram

The EGR system reduces oxides of nitrogen (NOx) emissions by recirculating exhaust gas through the EGR valve and the intake manifold into the combustion chambers. The PCM memory includes the ideal EGR valve position for varying operating conditions.

The EGR valve position sensor detects the amount of EGR valve lift and sends it to the PCM. The PCM then compares it with the ideal lift in its memory (based on signals sent from other sensors). If there is any difference between the two, the PCM cuts current to the EGR valve.

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2003-2004 models

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.

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1. The EVAP canister is purged by drawing fresh air through it and into a port on the throttle body. The purging vacuum is controlled by the EVAP canister purge valve, which is open whenever engine coolant temperature is above 149°F (65°C).
2. When vapor pressure in the fuel tank is higher than the set valve of the EVAP two way valve, the valve opens and regulates the flow of fuel vapor to the EVAP canister.
3. During refueling, the fuel tank vapor control valve opens with the pressure in the fuel tank, and feeds the vapor to the EVAP canister.

2005-2006 models

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.

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1. 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 149°F (65°C).
2. During refueling, the fuel tank vapor control valve opens with the pressure in the fuel tank, and feeds the fuel vapor to the EVAP canister.

Intake Manifold Tuning (IMT) (Intake Manifold Runner Control (IMRC)) System

Engine power is adjusted by opening and closing the intake manifold tuning (IMT) (intake manifold runner control (IMRC)) actuator. When the valve is closed, there is high torque at low engine speed. When the valve is open, there is high torque at high engine speed. The intake manifold tuning (IMT) (intake manifold runner control (IMRC)) valve actuator contains a sensor that detects the IMT (IMRC) valve position and sends it to the PCM.

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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 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 blinks 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 or when the PCM is cleared 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 at 158°F (70°C) or higher.
2. Intake air temperature (IAT) at 20°F (-7°C) or higher.
3. Vehicle speed sensor (VSS) reads more then 25 mph (40 km/h).

Procedure

1. Connect the HDS to the vehicle's data link connector (DLC), and bring up the OBD status screen for DTC P0420 in the DTC 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 passed.
4. If the readiness code is still set to not 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 code are cleared when the battery is disconnected or when the PCM is cleared with the HDS.

1. Battery voltage is higher than 10.5 V.
2. The A/T in N or P position, and the engine stopped.

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.
4. Check the OBD status screen for EVAP DTCs P0456, and P0457 in the DTCs MENU with the HDS. If they are passed, readiness code is set. If they are not passed, go to the next step.
5. If the readiness code is still set to not completed, 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 or when the PCM is cleared with the HDS.

ECT at 140°F (60°C) or higher.

1. Connect the HDS to the vehicle's data link connector (DLC).
2. Start the engine.
3. 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 not completed to complete.
4. Check the OBD status screen for Air Fuel Ratio (A/F) Sensor DTCs P0133 or P2A00 in the DTCs MENU with the HDS. If they are passed, readiness is set. If they are not passed, go to the next step.
5. If the readiness code is still set to not completed, 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 in the ALL DATA LIST with the HDS. If the coolant temperature is lower than 140°F (60°C), let the engine warm up, 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 or when the PCM is cleared with the HDS.

1. Start the engine, and let it idle for 1 minute. The readiness code should switch from not completed to complete.
2. If the readiness code is still set to incomplete, 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.

EGR 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 or when the PCM is cleared with the HDS.

ECT at 176°F (80°C) or higher

1. Connect the HDS to the vehicle's data link connector (DLC).
2. Start the engine.
3. Drive at a steady speed with the A/T in D5 position 50-62 mph (80-100 km/h) or above for more than 10 seconds.
4. With the A/T in D5 position decelerate from 62 mph (100 km/h) or above by completely releasing the throttle for at least 5 seconds. If the engine is stopped during this procedure, go to step 3 and do the procedure again.
5. Check the OBD status screen for DTC P0401 in the DTC's MENU with the HDS. If it is passed, readiness is complete. If it is not passed, go to step 3 and retest.

See also:
• MIL CIRCUIT TROUBLESHOOTING
• PCM IDLE LEARN PROCEDURE
• THROTTLE BODY CLEANING
• BATTERY TEST
• STARTER CIRCUIT TROUBLESHOOTING
• FUEL PRESSURE TEST
• FUEL PUMP CIRCUIT TROUBLESHOOTING
• TROUBLESHOOTING
• IDLE SPEED INSPECTION
• THROTTLE BODY TEST
• ALTERNATOR FR SIGNAL CIRCUIT TROUBLESHOOTING
• BRAKE PEDAL POSITION SWITCH SIGNAL CIRCUIT TROUBLESHOOTING
• FUEL TANK REPLACEMENT
• HOW TO SET READINESS CODES
• ELECTRONIC THROTTLE CONTROL SYSTEM DIAGRAM
• EXHAUST GAS RECIRCULATION (EGR) SYSTEM DIAGRAM
• OBD STATUS