Engine Control System (Diagnostic Codes (P1604-P2A00) & Circuit Tests): Overview Scion xD I

DESCRIPTION

This DTC is stored when the engine does not start even though the STA signal is input or when the engine takes a long time to start, and when the engine speed is low or the engine stalls just after the engine starts.

Using the Techstream, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

It is necessary to check if the vehicle ran out of fuel before performing troubleshooting, as this DTC is also stored when there is engine starting trouble due to running out of fuel.

1. *1: for Automatic Transaxle Models

1. *2: for Manual Transaxle Models

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1. Reference waveforms showing a normal cold engine start
2. Reference waveforms showing a normal warm engine start
3. Reference waveforms showing an engine stop after normal idling
4. Reference values when there is an air leak in the intake system during starting difficulty FREEZE FRAME DATA P1604 STARTABILITY MALFUNCTION Freeze Frame Data P1604: Startability Malfunction Parameter -3 -2 -1 0 1 Unit Engine Speed 1497 794 334 249 249 rpm Calculate Load 34.5 28.2 32.1 87.8 87.4 % Vehicle Load 8.6 21.9 15.6 7.4 5.8 % MAF 1.70 2.31 0.70 0.25 0.20 gm/sec Atmosphere Pressure -0 -0 -0 -0 -0 psi(gauge) Coolant Temp 167 167 167 167 167 F Intake Air 93 93 93 93 93 F Ambient Temperature 66 66 66 66 66 F Battery Voltage 13.2 13.0 12.3 12.3 12.3 V Throttle Sensor Volt % 16.0 17.6 17.2 15.6 15.6 % Throttle Sensor #2 Volt % 48.2 50.1 49.4 47.8 47.8 % Throttle Sensor Position 0.0 0.0 0.0 0.0 0.0 % Throttle Motor DUTY 16.0 17.6 17.6 15.6 15.6 % Injector (Port) 3200 2560 2560 2560 2560 μs Injection Volume (Cylinder 1) 0.152 0.152 0.152 0.152 0.152 ml Fuel Pump/Speed Status ON ON ON ON ON EVAP (Purge) VSV 0.0 0.0 0.0 0.0 0.0 % Evap Purge Flow 0.0 0.0 0.0 0.0 0.0 % Purge Density Learn Value 0.000 0.000 0.000 0.000 0.000 EVAP Purge VSV OFF OFF OFF OFF OFF Target Air-Fuel Ratio 0.830 0.841 0.871 0.799 0.799 AF Lambda B1 S1 1.014 1.016 1.021 1.022 1.027 AFS Voltage B1 S1 3.37 3.38 3.40 3.41 3.42 V O2S B1 S2 0.82 0.31 0.07 0.05 0.03 V Short FT #1 0.0 0.0 0.0 0.0 0.0 % Long FT #1 0.0 -4.0 -4.7 -4.7 -4.7 % Total FT #1 -0.043 -0.043 -0.043 -0.043 -0.043 Fuel System Status #1 OL OL OL OL OL IGN Advance -4.0 2.0 4.0 0.0 0.0 deg Knock Feedback Value -3.0 -3.0 -3.0 -3.0 -3.0 CA Knock Correct Learn Value 14.0 14.0 14.0 14.0 14.0 CA EGR Step Position 0 0 0 0 0 step VVT Control Status #1 OFF OFF OFF OFF OFF Starter Signal Close Close Close Close Close

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MONITOR DESCRIPTION

The ECM continuously monitors its main and sub CPUs for the cruise control. This self-check ensures that the ECM is functioning properly. If outputs from the CPUs are different and deviate from the standards, the ECM will illuminate the MIL and set the DTC immediately.

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 (TP) sensor, which is mounted on the throttle body. The TP 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 ETCS (Electronic Throttle Control System) does not use a throttle cable.

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 sets a DTC.

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

The idling speed is controlled by the Electronic Throttle Control System (ETCS).

The ETCS is comprised of a throttle actuator, which operates the throttle valve, and a throttle position sensor, which detects the opening amount of the throttle valve.

The ECM controls the throttle actuator to adjust the throttle valve opening amount so that the idling speed is maintained at the target idling speed.

If there are deposits in the throttle valve, the necessary ISC flow rate for idling is maintained using the ISC learning value and feedback as a decrease in the ISC flow rate may cause engine stall or unstable idling. The ECM stores this DTC if the ISC learning value approaches its limit.

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 (TP) sensor, which is mounted on the throttle body. The TP 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 ETCS (Electronic Throttle Control System) does not use a throttle cable.

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

If the malfunction is not repaired successfully, a DTC is set 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 ETCS (Electronic Throttle Control System) has a dedicated power supply circuit. The voltage (+BM) is monitored and when it is low (less than 4 V), the ECM determines that there is a malfunction in the ETCS and cuts off the current to the throttle actuator.

When the voltage becomes unstable, the ETCS 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 to OFF. The ECM then allows the current to flow to the throttle actuator so that it can be restarted.

HINT

The ETCS does not use a throttle cable.

Scheme 235

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 sets the DTC.

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

The Electronic Throttle Control System (ETCS) is composed of the throttle actuator, Throttle Position (TP) sensor, Accelerator Pedal Position (APP) sensor, and ECM. The ECM operates the throttle actuator to regulate the throttle valve in response to driver inputs. The TP 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 TP sensor signal. The actual opening angle is compared to the target opening angle commanded by the ECM. If the difference between these two values is outside the standard range, the ECM interprets this as a malfunction in the ETCS. The ECM then illuminates the MIL and sets the DTC.

If the malfunction is not repaired successfully, the DTC is set when the accelerator pedal is quickly released (to close the throttle valve) after the engine speed reaches 5000 rpm by fully depressing the accelerator pedal (fully open the throttle valve).

The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type and uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds. The voltage, which is applied to terminals VPA and VPA2 of the ECM, varies between 0.5 V and 4.5 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal opening angle (throttle valve opening angle) and is used for engine control. A signal from VPA2 conveys the status of the VPA circuit and is used to check the APP sensor itself.

The ECM monitors the actual accelerator pedal opening angle (throttle valve opening angle) through the signals from VPA and VPA2, and controls the throttle actuator according to these signals.

HINT

1. This ETCS (Electronic Throttle Control System) does not use a throttle cable.
2. These DTCs relate to the Accelerator Pedal Position (APP) sensor.

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HINT

When any of these DTCs are set, check the APP sensor voltage by selecting the following menu items using the Techstream: Powertrain / Engine and ECT / Data List / Accel Sensor Out No. 1 and Accel Sensor Out No. 2.

HINT

Accelerator pedal positions are expressed as voltages.

When either output voltage of VPA or VPA2 deviates from the standard range, or the difference between the output voltages of the 2 sensor circuits is less than the threshold, the ECM determines that there is a malfunction in the APP sensor. The ECM then illuminates the MIL and sets a DTC.

Example

When the output voltage of VPA drops below 0.4 V for more than 0.5 seconds when the accelerator pedal is fully depressed, DTC P2122 is set.

If the malfunction is not repaired successfully, a DTC is set 2 seconds after the engine is next started.

Refer to DTC P2120. Refer to DESCRIPTION.

HINT

1. This DTC relates to the Accelerator Pedal Position (APP) sensor.

When the difference between the output voltages of VPA and VPA2 deviates from the standard, the ECM determines that the accelerator pedal position sensor is malfunctioning. The ECM turns on the MIL and the DTC is set.

The A/F sensor generates a 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 time. If the A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.

The A/F sensor is the planar type and is integrated with the 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), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are the narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and therefore the sensor activation is accelerated.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

*: Value changes inside the ECM. Since the A/F sensor is the current output element, a current is converted into a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.

HINT

1. Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
2. Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

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HINT

1. When any of these DTCs are set, check the A/F sensor voltage output by selecting the following menu items on the Techstream: Powertrain / Engine and ECT / Data List / All Data / AFS Voltage B1S1.
2. Short-term fuel trim values can also be read using the Techstream.
3. The ECM regulates the voltages at the A1A+ and A1A- terminals of the ECM to a constant level. Therefore, the A/F sensor voltage output cannot be confirmed without using the Techstream.
4. If a A/F sensor malfunction is detected, the ECM sets a DTC.

Sensor voltage detection monitor

Under the air-fuel ratio feedback control, if the Air Fuel Ratio (A/F) sensor voltage output indicates rich or lean for a certain period of time, the ECM determines that there is a malfunction in the A/F sensor. The ECM illuminates the MIL and sets a DTC.

Example

If the air fuel ratio sensor voltage output is below 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 stores DTC P2196. Alternatively, if the air fuel ratio sensor voltage output is higher 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 is stored.

Sensor current detection monitor

A rich air-fuel mixture causes a low A/F sensor current, and a lean air-fuel mixture causes a high A/F 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 A/F sensor current during fuel-cut and detects any abnormal current values.

If the A/F sensor output is 2.2 mA or more for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the A/F sensor and sets DTC P2195 (high-side stuck). If the A/F sensor output is less than 0.7 mA for more than 3 seconds of cumulative time, the ECM sets DTC P2196 (low-side stuck).

Scheme 238

The A/F sensor, which is located between the exhaust manifold and catalyst, consists of alloyed metal elements and a heater.

Depending on the engine operating conditions, the heater heats the sensor elements to activate them. Battery voltage is applied to the heater, and the sensor ground is controlled by the ECM using a duty ratio.

The sensor elements convert the oxygen concentration in the exhaust gas into voltage values to output. Based on the voltage, the ECM determines the air-fuel ratio and regulates the fuel injection volume depending on the air-fuel ratio and engine operating conditions. The voltage changes between 0.6 V and 4.5 V while the engine is running. If the air-fuel ratio is lean, which means that the oxygen concentration in the exhaust gas is high, the voltage is high. If the air-fuel ratio is rich, which means that the oxygen concentration in the exhaust gas is low, the voltage is low.

HINT

1. Although the DTC titles say oxygen sensor, these DTCs relate to the Air Fuel Ratio (A/F) sensor.
2. Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

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These DTCs are output when there is an open or short in the Air Fuel Ratio (A/F) sensor circuit, or if A/F sensor output drops. To detect these problems, the voltage of the A/F sensor is monitored when turning the ignition switch to the ON position, and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the A/F sensor is between 0.6 V and 4.5 V, it is considered normal. If the voltage is out of the specified range, or the admittance is less than the standard value, the ECM will determine that there is a malfunction in the A/F sensor. If the same malfunction is detected in next driving cycle, the MIL will be illuminated and a DTC will be stored.

The description can be found in the EVAP (Evaporative Emission) System. Refer to DESCRIPTION.

5 hours* after the ignition switch is turned to OFF, the leak detection pump creates negative pressure (vacuum) in the EVAP system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT

*: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned to OFF, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the ignition switch is turned to OFF, the monitor check starts 2.5 hours later.

*: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

Scheme 241

P2420: 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 open, the ECM interprets this as the vent valve being stuck open. The ECM illuminates the MIL and sets the DTC.

Scheme 242

1. 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 which can only be performed after the engine is stopped. The soak timer is built into the ECM.

Scheme 243

1. 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 stores the DTC.
2. 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 ON.

Refer to DTC P2195. Refer to DESCRIPTION.

HINT

1. Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

After engine is warmed up, the ECM performs air-fuel ratio feedback control to maintain the air-fuel ratio at the stoichiometric level. In addition, active A/F control is performed for approximately 10 seconds after preconditions are met in order to measure the Air Fuel Ratio (A/F) sensor response rate. During active A/F control, the ECM forcibly increases and decreases the injection volume a certain amount, based on the stoichiometric air-fuel ratio learned during normal air-fuel ratio control, and measures the A/F sensor response rate. The ECM receives a signal from the A/F sensor while performing active A/F control and uses it to calculate the A/F sensor response rate deterioration level.

If the value for A/F sensor response rate deterioration level is less than the threshold, the ECM interprets this as a malfunction and sets the DTC.

Scheme 244

HINT

Unit expressions

1. [kPa-a (mmHg-a)] denotes the absolute pressure.
2. [kPa-g (mmHg-g)] denotes the gauge pressure (relative pressure).
3. On the Techstream, convert the unit of measurement according to the inspection procedure.

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Note. In this vehicle's EVAP system, turning ON the vent valve does not seal off the EVAP system. To check for leaks in the EVAP system, disconnect the air inlet vent hose and apply pressure from the atmospheric side of the canister.

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

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

The following two monitors run to confirm the appropriate EVAP system operation.

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1. Key-off monitor This monitor checks for EVAP (Evaporative Emission) system leaks and canister pump module malfunctions. The monitor starts 5 hours* after the ignition switch is turned to OFF. At least 5 hours are required for the fuel to cool down to stabilize the EVAP pressure, thus making the EVAP system monitor more accurate. The leak detection pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured. Finally, the ECM monitors for leaks from the EVAP system, and malfunctions in both the canister pump module and purge VSV, based on the EVAP pressure. HINT: *: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned to OFF, the monitor check starts 2 hours later. If it is still not below 35°C (95°F) 7 hours after the ignition switch is turned to OFF, the monitor check starts 2.5 hours later.
2. Purge flow monitor The purge flow monitor consists of 2 monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary. The 1st monitor While the engine is running and the purge VSV (Vacuum Switching Valve) is ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor. The 2nd monitor The vent valve is turned ON (closed) and the EVAP pressure is measured. If the variation in the pressure is less than 0.4 kPa-g (3.0 mmHg-g), the ECM interprets this as the purge VSV being stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic). Atmospheric pressure check: In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after conduction of the purge flow monitor, is measured by the ECM. Component Operation Canister Contains activated charcoal to absorb EVAP (Evaporative Emissions) generated in fuel tank. Cut-off valve Located in fuel tank. Valve floats and closes when fuel tank 100% full. Purge VSV (Vacuum Switching Valve) Opens or closes line between canister and intake manifold. ECM uses purge VSV to control EVAP purge flow. In order to discharge EVAP absorbed by canister to intake manifold, ECM opens purge VSV. EVAP discharge volume to intake manifold controlled by purge VSV duty cycle ratio (current-carrying time) (Open: ON; Closed: OFF). Refueling valve Controls EVAP pressure from fuel tank to canister. Valve consists of diaphragm, spring and restrictor (diameter: 0.08 inch). When fuel vapor and pressure inside fuel tank increase, valve opens. While EVAP purged, valve closes and restrictor prevents large amount of vacuum from affecting pressure in fuel tank. Valve opened while refueling. Roll-over valve Located in fuel tank. Valve closed by its own weight when vehicle overturns to prevent fuel from spilling out. Soak timer Built into ECM. To ensure accurate EVAP monitor, measures 5 hours (+/-15 min.) after ignition switch turned to OFF. This allows fuel to cool down, stabilizing EVAP pressure. When approximately 5 hours elapsed, ECM activates see scheme 86 Canister pump module Consists of (a) to (d) below. Canister pump module cannot be disassembled. (a) Vent valve Vents and closes EVAP system. When ECM turns valve ON, EVAP system closed. When ECM turns valve OFF, EVAP system vented. Negative pressure (vacuum) created in EVAP system to check for EVAP leaks by closing purge VSV, turning on vent valve (closed) and operating leak detection pump (Scheme 244) (b) Canister pressure sensor Indicates pressure as voltages. ECM supplies regulated 5 V to canister pressure sensor, and uses feedback from sensor to monitor EVAP system pressure see scheme 85 (c) Leak detection pump Creates negative pressure (vacuum) in EVAP system for leak check. (d) Reference orifice Has opening with 0.02 inch diameter. Vacuum produced through orifice by closing purge VSV, turning off vent valve and operating leak detection pump, to monitor reference pressure. Reference pressure indicates small leak of EVAP.

Scheme 250

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

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1. INSPECT INTEGRATION NO. 1 RELAY (POWER SOURCE) Remove the integration relay from the engine room relay block. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition 1C-1 - Body ground Always 11 to 14 V Reinstall the integration relay. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY - BATTERY) OK: Go to next step
2. INSPECT INTEGRATION NO. 1 RELAY (AM2 FUSE AND EFI FUSE) Remove the AM2 fuse and EFI fuse from the integration relay. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition AM2 fuse Always Below 1 ohms EFI fuse Always Below 1 ohms Reinstall the fuses. NG --> CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE OK: Go to next step
3. INSPECT INTEGRATION NO. 1 RELAY (EFI RELAY AND IG2 RELAY) Remove the integration relay from the engine room relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1C-1 - 1B-4 When battery voltage not applied 10 kohms or higher When battery voltage applied to terminal 1B-2 - 1B-3 Below 1 ohms 1C-1 - 1A-4 When battery voltage not applied 10 kohms or higher When battery voltage applied to terminal 1A-2 - 1A-3 Below 1 ohms 1C-1 - 1B-1 Always Below 1 ohms Reinstall the integration relay. NG --> See step 11 OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM) Remove the integration relay from the engine room relay block. 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 A21-44 (MREL) - 1A-2 Always Below 1 ohms A21-2 (+B) - 1A-4 Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition A21-44 (MREL) - Body ground Always 10 kohms or higher A21-2 (+B) - Body ground Always 10 kohms or higher Reinstall the integration relay. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
5. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 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 C19-104 (E1) - Body ground Always Below 1 ohms Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
6. INSPECT ECM (IGSW TERMINAL VOLTAGE) Disconnect the ECM connectors. 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 A21-28 (IGSW) - C19-104 (E1) Ignition switch ON 11 to 14 V Reconnect the ECM connectors. Result Result Proceed to Outside standard range A Within standard range B B --> See step 12 A: Go to next step
7. INSPECT FUSE (IGN FUSE) Remove the IGN fuse from the main body ECU. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition IGN fuse Always Below 1 ohms Reinstall the IGN fuse. NG --> CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE OK: Go to next step
8. CHECK HARNESS AND CONNECTOR (ECM - INTEGRATION RELAY) Remove the integration relay from the engine room relay block. 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 A21-28 (IGSW) - 1B-4 Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition A21-28 (IGSW) - Body ground Always 10 kohms or higher Reinstall the integration relay. Reconnect the ECM connector. Result Result Proceed to Outside standard range A Within standard range B B --> See step 9 A --> REPAIR OR REPLACE HARNESS OR CONNECTOR
9. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - IGNITION SWITCH) Remove the integration relay from the engine room relay block. Disconnect the ignition switch connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition 1B-2 - F9-6 (IG2) Always Below 1 ohms 1B-3 - Body ground Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition F9-6 (IG2) - Body ground Always 10 kohms or higher Reinstall the integration relay. Reconnect the ignition switch connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
10. INSPECT IGNITION SWITCH Remove the ignition switch. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Switch Condition Specified Condition All terminals LOCK 10 kohms or higher 2 (ACC) - 4 (AM1) ACC Below 1 ohms 1 (IG1) - 2 (ACC) - 4 (AM1) ON 5 (AM2) - 6 (IG2) 1 (IG1) - 3 (ST1) - 4 (AM1) START 5 (AM2) - 6 (IG2) - 7 (ST2) Reinstall the ignition switch. NG --> See step 13 OK --> REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH - BATTERY)
11. REPLACE INTEGRATION NO. 1 RELAY. Refer to «REMOVAL»(ref-388735-S08410464852011031100000)
12. REPLACE ECM. Refer to «REMOVAL»(ref-388735-S27161698942011031100000)
13. REPLACE IGNITION SWITCH. Refer to «REMOVAL»(ref-388740-S24626244732011031100000)

The ECM constantly generates 5 V power from the battery voltage 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 262

When the VC circuit is short-circuited, the microprocessor in the ECM and sensors that are supplied with 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 ON. The MIL goes off when the engine is started.

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1. CHECK MIL Check that the Malfunction Indicator Lamp (MIL) lights up when turning the ignition switch to ON. OK MIL lights up NG --> See step 2 OK --> END
2. CHECK COMMUNICATION 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 tester and ECM. Result Result Proceed to Communication is not possible A Communication is possible B B --> See step 9 A: Go to next step
3. CHECK MIL (THROTTLE POSITION SENSOR) Disconnect the throttle body 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 body connector. B --> See step 10 A: Go to next step
4. CHECK MIL (ACCELERATOR PEDAL POSITION SENSOR) Disconnect the accelerator pedal 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 accelerator pedal position sensor connector. B --> See step 11 A: Go to next step
5. 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 12 A: Go to next step
6. CHECK MIL (CAMSHAFT POSITION SENSOR FOR INTAKE CAMSHAFT) Disconnect the camshaft position sensor (for intake camshaft) connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the camshaft position sensor (for intake camshaft). B --> REPLACE CAMSHAFT POSITION SENSOR (FOR INTAKE CAMSHAFT) A: Go to next step
7. CHECK MIL (CAMSHAFT POSITION SENSOR FOR EXHAUST CAMSHAFT) Disconnect the camshaft position sensor (for exhaust camshaft) connector. Turn the ignition switch to ON. Check the MIL. Result Result Proceed to MIL does not illuminate A MIL illuminates B Reconnect the camshaft position sensor (for exhaust camshaft). B --> REPLACE CAMSHAFT POSITION SENSOR (FOR EXHAUST CAMSHAFT) A: Go to next step
8. CHECK HARNESS AND CONNECTOR (VC CIRCUIT) Disconnect the throttle body connector. Disconnect the accelerator pedal position sensor connector. Disconnect the canister pump module connector. Disconnect the camshaft position sensor (for intake camshaft) connector. Disconnect the camshaft position sensor (for exhaust camshaft) connector. Disconnect the ECM connectors. Measure the resistance. Standard Resistance (Check for Short) Tester Connection Condition Specified Condition C19-67 (VCTA) - Body ground Always 10 kohms or higher A21-57 (VCPA) - Body ground Always 10 kohms or higher A21-58 (VCP2) - Body ground Always 10 kohms or higher C19-69 (VCPP) - Body ground Always 10 kohms or higher C19-70 (VCVI) - Body ground Always 10 kohms or higher C19-117 (VC) - Body ground Always 10 kohms or higher Reconnect the throttle body connector. Reconnect the accelerator pedal position sensor connector. Reconnect the canister pump module connector. Reconnect the camshaft position sensor (for intake camshaft) connector. Reconnect the camshaft position sensor (for exhaust camshaft) connector. Reconnect the ECM connectors. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 13
9. GO TO MIL CIRCUIT. Refer to «MIL Circuit»(ref-388739-S37981725752011031100000)
10. REPLACE THROTTLE BODY. Refer to «REMOVAL»(ref-388735-S12806086742011031100000)
11. REPLACE ACCELERATOR PEDAL ROD ASSEMBLY. Refer to «REMOVAL»(ref-388735-S04914580752011031100000)
12. REPLACE CANISTER. Refer to «REMOVAL»(/scion/xd/i-2007-2014/remont/auxiliary-emission-control-systems/#emission-control-service-information)
13. REPLACE ECM. Refer to «REMOVAL»(ref-388735-S27161698942011031100000)

When the engine is cranked, the starter relay drive signal from the ignition switch is input into the STA terminal of the ECM, and the NE signal generated by the crankshaft position sensor is also input into the NE+ terminal. Thus, the ECM interprets that the engine is being cranked, and turns transistor Tr1 in the ECM internal circuit ON. The current flows to the C/OPN (Circuit Opening) relay by turning Tr1 ON. Then, the fuel pump operates.

While the NE signal is input into the ECM, and the engine is running, the ECM turns Tr1 on continuously.

Scheme 266

Scheme 267

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

Scheme 268

The cranking holding control system keeps energizing the starter relay from when the ECM detects the starter signal (STSW signal) from the ignition switch until the ECM performs a judgement of "Engine started". Furthermore, the ECM outputs an accessory cut signal (ACCR signal) to the ACC cut relay during cranking to prevent flickering of the combination meter, clock, audio system, and so on.

When the ECM detects the STSW signal, the ECM outputs the starter relay drive signal (STAR signal) to the starter relay through the clutch start switch or the park/neutral position switch, and then, the engine is cranked. When the ECM receives a stable engine speed signal (NE signal), more specifically, when the NE signal reaches a predetermined value, the ECM stops outputting the STAR signal.

Also, the ECM monitors the starter relay operating conditions based on the STA terminal voltage status.

Scheme 269

Scheme 270

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunction detections by the ECM. When the ignition switch is turned 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 be illuminated and should then turn off. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the Techstream.

Scheme 271

See also:
• ON-VEHICLE INSPECTION - Step 2
• ON-VEHICLE INSPECTION
• ON-VEHICLE INSPECTION
• ON-VEHICLE INSPECTION - Step 8
• REMOVAL
• INSPECTION