Toyota Avalon (XX50): Precaution. Problem Symptoms Table. Speed Signal Circuit

Precaution

PRECAUTION

NOTICE:

When disconnecting the cable from the negative (-) battery terminal, initialize the following systems after the cable is reconnected.

PRECAUTION FOR DISCONNECTING CABLE FROM NEGATIVE BATTERY TERMINAL

PRECAUTION FOR REPLACING COMBINATION METER ASSEMBLY

When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

FUEL RECEIVER GAUGE OPERATION

(a) OPERATION

The combination meter assembly uses the fuel sender gauge assembly to detect the amount of fuel remaining in the fuel tank assembly. The Hall IC built into the fuel sender gauge assembly changes the output voltage according to the amount of fuel remaining. The combination meter assembly receives fuel injection volume signals from the ECM and detects the voltage output from the fuel sender gauge assembly and operates the fuel receiver gauge.

(b) FUEL RECEIVER GAUGE READING

(1) During normal driving:

As the fuel level in the fuel tank assembly changes when driving on a hill or applying the brakes, the fuel receiver gauge reading is updated according to the fuel injection volume during normal driving. However, as the fuel injection volume measurement has a margin of error, the value is indicated after correction by input values from the fuel sender gauge assembly.

(2) During refueling:

The fuel level in the fuel tank assembly rises rapidly when fuel is added. If the averaging process that is used during normal driving is used in this case, the fuel receiver gauge reading cannot be updated promptly. Therefore, when it is judged that fuel is being added to the vehicle based on the changes in the fuel level, output values from the fuel sender gauge assembly is immediately reflected in the fuel receiver gauge reading. This control is called refueling judgment.

(c) REFUELING JUDGMENT CONDITIONS

NOTICE:

Add fuel with the engine switch off to ensure safety and to enable refueling judgment so that an appropriate fuel receiver gauge reading will be obtained.

(1) Normal judgment condition (When normal refueling method is used)

With the engine switch off, the fuel sender gauge assembly detects a change of 5.0 liters (5.3 US qts, 4.4 Imp. qts) or more in the fuel level.

(2) Other judgment conditions (When other refueling method is used)

Any of the following conditions is met:

• With the vehicle and engine stopped and the engine switch on (IG), the fuel sender gauge assembly detects a change of 5.0 liters (5.3 US qts, 4.4 Imp. qts) or more in the fuel level.
• With the vehicle stopped, the engine switch is on (IG), the fuel sender gauge assembly detects a change of 15.0 liters (15.9 US qts, 13.2 Imp. qts) or more in the fuel level.

(d) PRECAUTION FOR REFUELING

(1) The fuel sender gauge assembly cannot detect changes in the fuel level within certain ranges (around points E and F). Therefore, even if 5.0 liters (5.3 US qts, 4.4 Imp. qts) or more of fuel is added, refueling judgment may not be performed and the fuel receiver gauge reading may not change when fuel level is within such ranges.

(2) The fuel sender gauge reading takes approximately 25 seconds to rise from point E to F. If the vehicle is driven while the fuel sender gauge reading is rising, the fuel sender gauge reading will stop rising. After the fuel sender gauge reading stops rising, normal fuel sender gauge reading operation begins. The fuel sender gauge reading takes approximately 1 minutes per 1 liter (1.1 US qts, 0.9 Imp. qts) to rise while the vehicle is being driven, and takes approximately 8 minutes per 1 liter (1.1 US qts, 0.9 Imp. qts) to rise while the vehicle is stopped.

(e) FORCED RESET OF FUEL RECEIVER GAUGE

When driving at a vehicle speed of 1.8 km/h (1 mph) or more, if the output value from the fuel sender gauge assembly is different from the fuel receiver gauge reading by 15.0 liters (15.9 US qts, 13.2 Imp. qts) or more for approximately 5 minutes, the output value from the fuel sender gauge assembly is immediately reflected in the fuel receiver gauge reading to compensate for a situation when refueling judgment cannot be made.

SERVICE MODE (w/ Toyota Entune Remote Connect)

NOTICE:

• Before servicing, enter service mode to restrain telematics communication functions and prevent the Toyota Entune Remote Connect from being operated while servicing.
• Service mode can be entered by using the Techstream or operating the radio and display receiver assembly.

(a) Service mode

HINT:

To cancel service mode, turn the engine switch off and on (IG) to display the service mode screen and cancel service mode.

(1) Service mode (Using the Techstream)

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Telematics / Trouble Codes.

(2) Service mode (When not using the Techstream)

1. Start diagnostic mode.

   w/o Navigation System: Click here

   w/ Navigation System: Click here

Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

HINT:

• The following problem symptoms table is based on the assumption that each system related to the combination meter assembly is normal.
• Refer to System Description for details about the communication between the combination meter assembly and each ECU.

  Click here

• Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
• Inspect the fuses and relays related to this system before inspecting the suspected areas below.

Speed Signal Circuit

DESCRIPTION

The combination meter assembly receives the vehicle speed signal from this circuit. The wheel speed sensors produce an output that varies according to the vehicle speed. The wheel speed sensor output is received by the skid control ECU (brake actuator assembly) which uses this information to create the vehicle speed signal*. The vehicle speed signal consists of pulses sent to the combination meter assembly from the skid control ECU (brake actuator assembly). To create this signal, 12 V is output from IG2 which is behind a resistor in the combination meter assembly. This voltage is sent to the skid control ECU (brake actuator assembly). The pulse signal is created by switching the transistor in the skid control ECU (brake actuator assembly) on and off, making the voltage on the wire drop to 0 V. A similar system is used for the output of this signal from the combination meter assembly via terminal +S. A voltage of 12 V is applied to terminal +S from each ECU or relay that is connected to this terminal. The transistor in the combination meter assembly is controlled by the signal from the skid control ECU (brake actuator assembly). When this transistor is turned on, this transistor makes the voltage supplied by the various ECUs (via their respective internal resistors) drop to 0 V. Each ECU connected to terminal +S of the combination meter assembly controls its respective system based on this pulse signal.

• *: This vehicle speed signal is created by the skid control ECU (brake actuator assembly). There is no actual component that is referred to as the vehicle speed sensor. In addition, for some systems, vehicle speed information may be received via CAN communication.

HINT:

This circuit is used for the systems connected to terminal +S. This signal is not used for combination meter assembly operation. Combination meter assembly components such as the speedometer operate using data received via CAN communication.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

PROCEDURE

(a) Disconnect the A28 skid control ECU (brake actuator assembly) connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

NG

GO TO STEP 5

OK

(a) Connect the A28 skid control ECU (brake actuator assembly) connector.

(b) Remove the combination meter assembly with the connector(s) still connected.

(c) Check the signal waveform according to the condition(s) in the table below.

OK:

The waveform is similar to that shown in the illustration.

HINT:

When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

NG

REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)

OK

(a) Disconnect the G16 combination meter assembly connector.

(b) Disconnect the A18 ECM connector.

(c) Disconnect the G40 certification ECU (smart key ECU assembly) connector.

(d) Disconnect the G9 DCM (telematics transceiver)*1 connector.

(e) Disconnect the G3 radio and display receiver assembly connector.

(f) Disconnect the G8 stereo component amplifier assembly*2 connector.

(g) Disconnect the G13 navigation ECU*3 connector.

(h) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

• *1: w/ Manual (SOS) Switch
• *2: for 14 Speakers
• *3: w/ Navigation System

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

(a) Connect the G16 combination meter assembly connector.

(b) Connect a positive (+) lead from the battery to any of the following terminals:

• A18-39 (SPD) ECM connector
• G40-19 (SPD) certification ECU (smart key ECU assembly) connector
• G9-10 (SPDP) DCM (telematics transceiver)*1 connector
• G3-27 (SPD) radio and display receiver assembly connector
• G8-11 (SPD) stereo component amplifier assembly*2 connector
• G13-9 (SPD) navigation ECU*3 connector
  • *1: w/ Manual (SOS) Switch
  • *2: for 14 Speakers
  • *3: w/ Navigation System

(c) Check the signal waveform according to the condition(s) in the table below.

OK:

The waveform is similar to that shown in the illustration.

HINT:

• When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.
• If the result is OK, an internal malfunction of a connected ECU can be suspected.
• If the result is NG, an internal malfunction of the combination meter assembly can be suspected.

OK

REPLACE DEFECTIVE ECU

NG

REPLACE COMBINATION METER ASSEMBLY

(a) Disconnect the G16 combination meter assembly connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

OK

REPLACE COMBINATION METER ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR