Engine Control System (Diagnostic Codes (P1451-U0293) & Circuit Tests) (Hybrid): Overview Toyota Highlander II рестайлинг

DESCRIPTION

The description can be found in the EVAP (evaporative emission) System, refer to DESCRIPTION.

Scheme 786

1. P1451: Pressure sensor abnormal voltage fluctuation or being constant If the pressure sensor output voltage fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC. Alternatively, if the sensor output voltage does not change for 10 seconds, the ECM interprets this as the sensor voltage being constant, and stops the monitor. The ECM then illuminates the MIL and sets the DTC. (Both the malfunctions are detected by 2 trip detection logic).
2. P1452: Pressure sensor voltage low If the pressure sensor output voltage is below 0.45 V, the ECM interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).
3. P1453: Pressure sensor voltage high If the pressure sensor voltage output is 4.9 V or more, the ECM interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).

The throttle actuator is operated by the ECM and opens and closes the throttle valve using gears.

The opening angle of the throttle valve is detected by the throttle position sensor, which is mounted on the throttle with motor body assembly. The throttle position sensor provides feedback to the ECM. This feedback allows the ECM to appropriately control the throttle actuator and monitor the throttle opening angle as the ECM responds to driver inputs.

HINT

This electronic throttle control system does not use a throttle cable.

MONITOR DESCRIPTION

The ECM monitors the electrical current through the electronic actuator, and detects malfunctions and open circuits in the throttle actuator based on this value. If the current is outside the standard range, the ECM determines that there is a malfunction in the throttle actuator. In addition, if the throttle valve does not function properly (for example, stuck on), the ECM determines that there is a malfunction. The ECM then illuminates the MIL and stores a DTC.

Example

1. When the electrical current is below 0.5 A and the throttle actuator duty ratio exceeds 80%, the ECM interprets this as the current being outside the standard range, illuminates the MIL and stores a DTC.
2. If the malfunction is not repaired successfully, a DTC is stored when the engine is quickly revved to a high engine speed several times after the engine has idled for 5 seconds after engine start.

The throttle actuator is operated by the ECM, and opens and closes the throttle valve using gears. The opening angle of the throttle valve is detected by the throttle position sensor, which is mounted on the throttle with motor body assembly. The throttle position sensor provides feedback to the ECM. This feedback allows the ECM to appropriately control the throttle actuator and monitor the throttle opening angle as the ECM responds to driver inputs.

HINT

This electronic throttle control system does not use a throttle cable.

The ECM determines that there is a malfunction in the electronic throttle control system when the throttle valve remains at the fixed angle despite a high drive current from the ECM. The ECM illuminates the MIL and stores a DTC.

If the malfunction is not repaired successfully, a DTC is stored when the accelerator pedal is fully depressed and released quickly (to fully open and close the throttle valve) after the engine is next started.

The electronic throttle control system has a dedicated power supply circuit. The voltage (+BM) is monitored and when it is low (below 4 V), the ECM determines that there is a malfunction in the electronic throttle control system and cuts off the current to the throttle actuator.

When the voltage becomes unstable, the electronic throttle control system itself becomes unstable. For this reason, when the voltage is low, the current to the throttle actuator is cut. If repairs are made and the system returns to normal, turn the ignition switch off. The ECM then allows the current to flow to the throttle actuator so that it can be restarted.

HINT

This electronic throttle control system does not use a throttle cable.

Scheme 787

The ECM monitors the battery supply voltage applied to the throttle actuator.

When the power supply voltage (+BM) drops below 4 V for 0.8 seconds or more, the ECM interprets this as an open in the power supply circuit (+BM). The ECM illuminates the MIL and stores the DTC.

If the malfunction is not repaired successfully, the DTC is stored 5 seconds after the engine is next started.

The electronic throttle control system is composed of the throttle actuator, throttle position sensor, accelerator pedal position sensor, and ECM. The ECM operates the throttle actuator to regulate the throttle valve in response to driver inputs. The throttle position sensor detects the opening angle of the throttle valve, and provides the ECM with feedback so that the throttle valve can be appropriately controlled by the ECM.

The ECM determines the actual opening angle of the throttle valve from the throttle position sensor signal. The actual opening angle is compared to the target opening angle commanded by the ECM. If the difference between these 2 values is outside the standard range, the ECM interprets this as a malfunction in the electronic throttle control system. The ECM then illuminates the MIL and stores the DTC.

If the malfunction is not repaired successfully, the DTC is stored when the accelerator pedal is quickly released (to close the throttle valve) after the engine speed reaches 5000 RPM by the accelerator pedal being fully depressed (fully opening the throttle valve).

The air fuel ratio sensor generates voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection duration. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is a planar type with an integrated heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), current flows to the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.

A three-way catalytic converter is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less harmful substances. To allow the three-way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the stoichiometric air fuel ratio.

*: Value changes inside the ECM. Since the air fuel ratio sensor uses the current output element, the current is converted to a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

Scheme 788

HINT

1. DTCs P2195 and P2196 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
2. DTCs P2197 and P2198 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.
3. When any of these DTCs are set, check the air fuel ratio sensor output voltage by entering the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / AFS Voltage B1S1 or AFS Voltage B2S1.
4. Short-term fuel trim values can also be read using the Techstream.
5. The ECM regulates the voltages at the A1A+, A2A+, A1A- and A2A- terminals of the ECM to a constant level. Therefore, the air fuel ratio sensor output voltage cannot be confirmed without using the Techstream.
6. If an air fuel ratio sensor malfunction is detected, the ECM sets a DTC.

Scheme 789

1. Sensor voltage detection monitor
2. Under the air fuel ratio feedback control, if the air fuel ratio sensor output voltage indicates rich or lean for a certain period of time, the ECM determines that there is a malfunction in the air fuel ratio sensor. The ECM illuminates the MIL and sets a DTC. Example: If the air fuel ratio sensor voltage output is less than 2.8 V (very rich condition) and heated oxygen sensor output voltage falls from 0.59 V or more to less than 0.21 V for 5 seconds, the ECM sets DTC P2196 or P2198. Alternatively, if the air fuel ratio sensor voltage output is more than 3.8 V (very lean condition) and heated oxygen sensor output voltage rises from less than 0.21 V to 0.59 V or more for 5 seconds, DTC P2195 or P2197 is set. Sensor current detection monitor A rich air fuel mixture causes a low air fuel ratio sensor current, and a lean air fuel mixture causes a high air fuel ratio sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration with the throttle valve fully closed. The ECM monitors the air fuel ratio sensor current during fuel cut and detects any abnormal current values. If the air fuel ratio sensor output is 3.6 mA or more for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the air fuel ratio sensor and sets DTC P2195 or P2197 (high-side stuck). If the air fuel ratio sensor output is 1.0 mA or less for more than 3 seconds of cumulative time, the ECM sets DTC P2196 or P2198 (low-side stuck).

Refer to P0300, refer to DESCRIPTION.

Refer to P2195, refer to DESCRIPTION.

Fuel System Air-fuel Ratio Cylinder Imbalance Monitor

The ECM uses the A/F sensor monitoring method and the crankshaft position sensor monitoring method to monitor injector injection volume inconsistencies and air fuel ratio imbalance between the cylinders due to leaks in the air intake/exhaust system, etc.

If the air fuel ratios between the cylinders are inconsistent due to cylinders being lean or rich, the ECM stores a DTC.

A/F Sensor Monitoring Method

When the ECM detects an air fuel ratio imbalance between the cylinders based on the fluctuations in A/F sensor output through all 4 strokes of one cycle (2 rotations of the crankshaft), the ECM determines that there is a malfunction.

Crankshaft Position Sensor Monitoring Method

The ECM monitors engine speed fluctuations. When the engine speed fluctuates significantly, the ECM judges this as an air fuel ratio imbalance and then determines this as a malfunction.

Refer to DTC P2195, refer to DESCRIPTION.

HINT

1. DTCs P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
2. DTCs P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.

The air fuel ratio sensor varies its output voltage in proportion to the air fuel ratio. If the air fuel ratio sensor impedance (alternating current resistance) or voltage output deviates greatly from the standard range, the ECM determines that there is an open or short in the air fuel ratio sensor circuit.

The circuit description can be found in the EVAP (evaporative emission) System, refer to DESCRIPTION.

Vent valve stuck open (vent)

In operation C, the vent valve turns on (closes) and the EVAP system pressure is then measured by the ECM, using the canister pressure sensor, to conduct an EVAP leak check. If the pressure does not increase when the vent valve is opened, the ECM interprets this as the vent valve being stuck open. The ECM illuminates the MIL and sets the DTC.

Scheme 790

Refer to the EVAP System, refer to DESCRIPTION.

Scheme 791

1. P2450: Fuel vapor-containment valve (FVCV) stuck open During sequence C, the vacuum pump creates vacuum in the EVAP system. If the pressure in the fuel tank drops, the ECM determines that the fuel vapor-containment valve is stuck open. The ECM then illuminates the MIL and sets the DTC. (This DTC is set according to 2 trip detection logic.)
2. P2451: Fuel vapor-containment valve (FVCV) stuck closed (vent) During sequence G, the fuel vapor-containment valve opens to allow vacuum pressure generated by the vacuum pump into the fuel tank. If the pressure in the fuel tank does not drop, the ECM determines that the fuel vapor-containment valve is stuck closed. The ECM then illuminates the MIL and sets the DTC. (This DTC is set according to 2 trip detection logic.) During sequence I, the tank close valve opens to allow atmospheric pressure into the fuel tank. If there is no change in fuel tank pressure, the ECM determines that the fuel vapor-containment valve is stuck closed. The ECM then illuminates the MIL and sets the DTC. (This DTC is set according to 2 trip detection logic.)

The soak timer operates after the ignition switch is turned off. When a certain amount of time has elapsed after turning the ignition switch off, the soak timer activates the ECM to perform malfunction checks witch can only be performed after the engine is stopped. The soak timer is built into the ECM.

Scheme 792

If the soak timer activates the ECM even though only a short amount of time has elapsed since the ignition switch was turned off, or if the soak timer does not activate the ECM even though a considerable amount of time has elapsed since the ignition switch was turned off, the ECM determines that the soak timer is malfunctioning, illuminates the MIL and stores a DTC the next time the ignition switch is turned to ON. While the engine is running, the ECM monitors the synchronization of the soak timer and the CPU clock. If these two are not synchronized, the ECM interprets this as a malfunction, illuminates the MIL and sets the DTC (2 trip detection logic).

From the hybrid vehicle control ECU, the ECM receives data such as power output required for the engine (required output), estimated torque produced by the engine (estimated torque), engine speed of control target (target engine speed), and whether the engine is in start mode or not. Then, based on the required output and target engine speed, the ECM calculates a target torque that is to be produced by the engine and compares it with the estimated torque. If the estimated torque is very low compared with the target torque, or the engine start mode continues for the specific duration calculated by the coolant temperature, an abnormal condition is detected.

The ECM and hybrid vehicle control ECU are connected by a communication line called CAN. The ECM sends engine speed data and other data to the hybrid vehicle control ECU while the hybrid vehicle control ECU sends the information such as a requirement for the engine power to the ECM using the CAN communication line. When the communication between the ECM and hybrid vehicle control ECU is normal and the following items become a specified condition, the ECM illuminates the MIL and sets a DTC.

1. Engine speed
2. Target torque
3. Ratio of target torque against estimated torque
4. Fuel level

The CAN (Controller Area Network) is a serial data communication system for real-time application. It is a multiplex communication system designed for on-vehicle use that provides a superior communication speed of 500 kbps and a capability to detect malfunctions. Through the combination of the CANH and CANL bus lines, the CAN is able to maintain communication based on differential voltage.

While the engine is running, if predetermined conditions (closed loop, etc.) are met, the purge VSV is opened by the ECM and stored fuel vapors in the canister are purged to the intake manifold. The ECM will change the duty cycle ratio of the purge VSV to control purge flow volume.

Purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed to enter the canister through the vent valve to ensure that purge flow is maintained when negative pressure (vacuum) is applied to the canister.

The ECM monitors the condition of both the key-off monitor and purge flow monitor to ensure proper operation of the EVAP system.

Scheme 793

TEXT IN ILLUSTRATION

Scheme 794

TEXT IN ILLUSTRATION

Scheme 795

TEXT IN ILLUSTRATION

Scheme 796

HINT

Standard atmospheric pressure is 101.3 kPa (760 mmHg-a)

Scheme 797

Key-off Monitor

This monitoring system checks for canister pump module malfunctions and leaks from the EVAP and closed tank systems. Be sure to leave the vehicle for at least 5 hours to sufficiently cool the fuel and stabilize fuel tank pressure. This makes EVAP system monitoring more accurate.

HINT

If the engine coolant temperature is 50°C (122°F) or more, 5 hours after the ignition switch has been turned off, the ECM will begin performing a monitor check after another 2 hours. If the engine coolant temperature is still 50°C (122°F) or more, 7 hours after the ignition switch has been turned off, the ECM will begin performing a monitor check after another 2.5 hours.

There are two methods for monitoring the EVAP system.

1. If the fuel tank pressure is higher or lower than the atmospheric pressure, the system determines that there are no leaks in the closed tank system and the system will check for leaks from the piping and canister between the purge VSV and canister pump module. (Method A)
2. If the fuel tank pressure is almost the same as the atmospheric pressure, vacuum will be allowed to enter the fuel tank and the system will check for leaks from the fuel tank after checking for leaks from the canister. (Method B)

Scheme 798

HINT

*: If there is only a small amount of fuel in the fuel tank, stabilizing the EVAP pressure takes longer than usual.

Scheme 799

TEXT IN ILLUSTRATION

Purge Flow Monitor

If EVAP system pressure change is less than 7.5 mmHg (1 kPa) when the engine is running and the purge VSV is turned on (closed), the ECM determines that the purge flow is insufficient.

Scheme 800

TEXT IN ILLUSTRATION

When the ignition switch is turned to ON, the battery voltage is applied to IGSW of the ECM. The output signal from the MREL terminal of the ECM causes a current to flow to the coil, closing the contact of the EFI MAIN relay and supplying power to terminals +B and +B2 of the ECM.

Scheme 801

The ECM constantly uses 5 V from the battery voltages supplied to the +B (BATT) terminal to operate the microprocessor. The ECM also provides this power to the sensors through the VC output circuit.

Scheme 802

When the VC circuit is shorted, the microprocessor in the ECM and sensors that are supplied power through the VC circuit are inactivated because the power is not supplied from the VC circuit. Under this condition, the system does not start up and the MIL does not illuminate even if the system malfunctions.

HINT

Under normal conditions, the MIL is illuminated for several seconds when the ignition switch is first turned to ON. The MIL goes off when the engine is started.

Scheme 803

Scheme 804

Scheme 805

Scheme 806

Scheme 807

Scheme 808

Scheme 809

1. CHECK MIL Check that the Malfunction Indicator Lamp (MIL) illuminates when turning the ignition switch to ON. OK MIL lights up. NG --> See step 2 OK --> See step 15
2. CHECK CONNECTION BETWEEN TECHSTREAM AND ECM Connect the Techstream to the DLC3. Turn the ignition switch to ON. Turn the Techstream on. Check the communication between the Techstream and ECM. Result Result Proceed to Communication is not possible A Communication is possible B B --> See step 16 A: Go to next step
3. CHECK MIL (THROTTLE POSITION SENSOR) Disconnect the throttle position sensor connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the throttle position sensor connector. B --> See step 17 A: Go to next step
4. CHECK MIL (VVT SENSOR FOR BANK 1) Disconnect the VVT sensor for bank 1 connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the VVT sensor for bank 1 connector. B --> See step 18 A: Go to next step
5. CHECK MIL (VVT SENSOR FOR BANK 2) Disconnect the VVT sensor for bank 2 connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the VVT sensor for bank 2 connector. B --> See step 19 A: Go to next step
6. CHECK MIL (MANIFOLD ABSOLUTE PRESSURE SENSOR) Disconnect the manifold absolute pressure sensor connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the manifold absolute pressure sensor connector. B --> See step 20 A: Go to next step
7. CHECK MIL (CANISTER PUMP MODULE) Disconnect the canister pump module connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the canister pump module connector. B --> See step 21 A: Go to next step
8. CHECK MIL (VAPOR PRESSURE SENSOR) Disconnect the vapor pressure sensor connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B B --> REPLACE VAPOR PRESSURE SENSOR A: Go to next step
9. CHECK HARNESS AND CONNECTOR (THROTTLE POSITION SENSOR - ECM) Disconnect the throttle position sensor connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition B57-118 (VCTA) or B27-5 (VC) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Throttle Position Sensor) *b Front view of wire harness connector (to ECM) Reconnect the throttle position sensor connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (THROTTLE POSITION SENSOR - ECM) OK: Go to next step
10. CHECK HARNESS AND CONNECTOR (VVT SENSOR FOR BANK 1 - ECM) Disconnect the VVT sensor for bank 1 connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition B74-3 (VC) or B57-78 (VCV1) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to VVT Sensor for Bank 1) *b Front view of wire harness connector (to ECM) Reconnect the VVT sensor for bank 1 connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (VVT SENSOR FOR BANK 1 - ECM) OK: Go to next step
11. CHECK HARNESS AND CONNECTOR (VVT SENSOR FOR BANK 2 - ECM) Disconnect the VVT sensor for bank 2 connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition B75-3 (VC) or B57-79 (VCV2) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to VVT Sensor for Bank 2) *b Front view of wire harness connector (to ECM) Reconnect the VVT sensor for bank 2 connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (VVT SENSOR FOR BANK 2 - ECM) OK: Go to next step
12. CHECK HARNESS AND CONNECTOR (MANIFOLD ABSOLUTE PRESSURE SENSOR - ECM) Disconnect the manifold absolute pressure sensor connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition B80-3 (VC) or B57-88 (VPIM) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Manifold Absolute Pressure Sensor) *b Front view of wire harness connector (to ECM) Reconnect the manifold absolute pressure sensor connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (MANIFOLD ABSOLUTE PRESSURE SENSOR - ECM) OK: Go to next step
13. CHECK HARNESS AND CONNECTOR (CANISTER PUMP MODULE - ECM) Disconnect the canister pump module connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition O42-4 (VCC) or A67-54 (VCPP) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Canister Pump Module) *b Front view of wire harness connector (to ECM) Reconnect the canister pump module connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (CANISTER PUMP MODULE - ECM) OK: Go to next step
14. CHECK HARNESS AND CONNECTOR (VAPOR PRESSURE SENSOR - ECM) Disconnect the vapor pressure sensor connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. STANDARD RESISTANCE Tester Connection Condition Specified Condition k1-3 (VC) or A67-55 (VC) - Body ground Always 10 kohms or higher Reconnect the vapor pressure sensor connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (VAPOR PRESSURE SENSOR - ECM) OK --> See step 22
15. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-426655-S00596471612011101200000)
16. GO TO MIL CIRCUIT. Refer to «MIL Circuit»(ref-426777-S04199343892011101200000)
17. REPLACE THROTTLE WITH MOTOR BODY ASSEMBLY. Refer to «REMOVAL»(ref-426780-S24526827482011101200000)
18. REPLACE VVT SENSOR FOR BANK 1. Refer to «REMOVAL»(ref-426780-S05381036062011101200000)
19. REPLACE VVT SENSOR FOR BANK 2. Refer to «REMOVAL»(ref-426780-S05381036062011101200000)
20. REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR. Refer to «REMOVAL»(ref-426780-S33332903882011101200000)
21. REPLACE CANISTER. Refer to «REMOVAL»(ref-426771-S12975672052011101200000)
22. REPLACE ECM. Refer to «REMOVAL»(ref-426780-S20256408682011101200000)

Refer to DTC P0230, refer to DESCRIPTION.

Scheme 810

The fuel injector assemblies are located on the intake manifold. They inject fuel into the cylinders based on signals from the ECM.

Scheme 811

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunctions detected by the ECM. By turning the ignition switch to ON, power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.

The MIL operation can be checked visually. When the ignition switch is first turned to ON, the MIL should illuminate and should then turn off. If the MIL remains illuminated or does not illuminate, conduct the following troubleshooting procedure. If the ECM detects any trouble, the MIL illuminates. At this time, the ECM records a DTC in the memory.

Scheme 812

Scheme 813

Scheme 814

1. CHECK THAT MIL ILLUMINATES Turn the ignition switch to ON. Check the illumination of the MIL. Result Result Proceed to MIL remains illuminated (Even after ignition switch is turned ON and several seconds have passed, MIL still remains illuminated) A MIL remains off (Does not illuminate at all) B MIL illuminates for several seconds, but turns off after engine is started C B --> See step 5 C --> See step 8 A: Go to next step
2. CHECK WHETHER MIL TURNS OFF Connect the Techstream to the DLC3. Turn the ignition switch to ON. Turn the Techstream on. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes. Check if any DTCs have been stored. Note any DTCs. Clear the DTCs, refer to «DTC CHECK / CLEAR»(ref-426655-S13741789592011101200000). Check if the MIL goes off. Result Result Proceed to MIL goes off A MIL does not go off B B --> See step 3 A --> REPAIR CIRCUIT INDICATED BY OUTPUT DTC
3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS) Disconnect the ECM connector. Turn the ignition switch to ON. Check if the MIL is illuminated. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the ECM connector. B --> See step 4 A --> See step 9
4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM) Disconnect the combination meter assembly connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition E1-10 (CHK) or A67-16 (W) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Combination Meter Assembly) *b Front view of wire harness connector (to ECM) Reconnect the combination meter assembly connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COMBINATION METER ASSEMBLY - ECM) OK --> See step 10
5. CHECK IF ENGINE STARTS Start the engine. Result Result Proceed to Engine starts A Engine does not start* B HINT: *: The Techstream cannot communicate with the ECM. B --> See step 11 A: Go to next step
6. CHECK HARNESS AND CONNECTOR (ECM TERMINAL VOLTAGE) Disconnect the ECM connector. Turn the ignition switch to ON. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition A67-16 (W) - Body ground Ignition switch ON 11 to 14 V TEXT IN ILLUSTRATION *a Front view of wire harness connector (to ECM) Reconnect the ECM connector. NG --> See step 7 OK --> See step 9
7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM) Disconnect the combination meter assembly connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition E1-10 (CHK) - A67-16 (W) Always Below 1 ohms TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Combination Meter Assembly) *b Front view of wire harness connector (to ECM) Reconnect the ECM connector. Reconnect the combination meter assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (COMBINATION METER ASSEMBLY - ECM) OK --> See step 12
8. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-426655-S00596471612011101200000)
9. REPLACE ECM. Refer to «REMOVAL»(ref-426780-S20256408682011101200000)
10. REPLACE COMBINATION METER ASSEMBLY. Refer to «REMOVAL»(ref-426792-S02311555142011101200000)
11. GO TO VC OUTPUT CIRCUIT. Refer to «VC Output Circuit»(ref-426777-S16220983162011101200000)
12. REPLACE COMBINATION METER ASSEMBLY. Refer to «REMOVAL»(ref-426792-S02311555142011101200000)

See also:
• ON-VEHICLE INSPECTION - Step 1
• ON-VEHICLE INSPECTION - Step 2
• ON-VEHICLE INSPECTION - Step 2
• REMOVAL