Toyota Avalon (XX50): Yaw Rate Sensor Output Value Malfunction (C1448). Calibration. Check For Intermittent Problems

Yaw Rate Sensor Output Value Malfunction (C1448)

DESCRIPTION

The skid control ECU (brake actuator assembly) receives signals from the yaw rate and acceleration sensor (airbag sensor assembly) via CAN communication.

The airbag sensor assembly has a built-in yaw rate and acceleration sensor and detects the vehicle condition.

CAUTION / NOTICE / HINT

NOTICE:

After replacing or reinstalling the yaw rate and acceleration sensor (airbag sensor assembly), perform system variant learning and acceleration sensor zero point calibration.

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PROCEDURE

(a) Clear the DTCs.

(b) Turn the engine switch off.

(c) Start and idle the engine.

(d) Drive the vehicle at a speed of 20 km/h (12 mph) or more for at least 120 seconds, and then stop the engine.

(e) Check if the same DTC is output.

A

REPLACE AIRBAG SENSOR ASSEMBLY

B

USE SIMULATION METHOD TO CHECK

Calibration

CALIBRATION

DESCRIPTION

(a) Refer to the table below and then perform the necessary operation according to the part to be replaced in order to perform calibration.

SYSTEM VARIANT LEARNING AND ACCELERATION SENSOR ZERO POINT CALIBRATION

NOTICE:

• While obtaining the zero point, keep the vehicle stationary and do not vibrate, tilt, move, or shake it.
• Be sure to perform this procedure on a level surface (with an inclination of less than 0.45 degrees).
• While obtaining the zero point, make sure the tire pressure is as specified and the vehicle is in full contact with the ground (not lifted up or loaded).

HINT:

When entering Test Mode, the skid control ECU (brake actuator assembly) communicates with the driving support ECU assembly to judge whether the vehicle is equipped with the pre-collision system. Therefore, do not exit Test Mode within 5 seconds of entering Test Mode.

(a) Perform system variant learning and acceleration sensor zero point calibration.

HINT:

• System variant learning and acceleration sensor zero point calibration are automatically performed immediately after Test Mode is entered.
• If learning has not yet been performed, the slip indicator light will remain on and DTC C1288 (Error in Matching of ECUs) will be stored.
• If system variant learning is not successful, the warning lights will not blink in the Test Mode pattern and DTC C1288 will not be cleared.
• If acceleration sensor zero point calibration is not successful, DTC C1336 will not be cleared.

(1) Turn the engine switch off.

(2) Check that the steering wheel is centered.

(3) Check that the shift lever is in P.

(4) Connect the Techstream to the DLC3.

(5) Turn the engine switch on (IG).

(6) Turn the Techstream on.

(7) Switch the skid control ECU (brake actuator assembly) to Test Mode using the Techstream. Enter the following menus: Chassis / ABS/VSC/TRAC/EPB / Utility / Test Mode.

(8) Check that the ABS warning, slip indicator and parking brake indicator lights blink in the Test Mode pattern.

HINT:

• After the skid control ECU (brake actuator assembly) enters Test Mode, the slip indicator light may remain on for approximately 7 seconds before starting to blink in the Test Mode pattern.
• Do not exit Test Mode within 5 seconds of entering Test Mode. If Test Mode is exited within 5 seconds of entering Test Mode, DTC U1104 may be stored. If DTC U1104 is output after exiting Test Mode, enter Test Mode again, wait at least 5 seconds, then recheck for DTCs.
• While the parking brake is engaged, the parking brake indicator light illuminates but does not blink in the Test Mode pattern.

(9) Turn the engine switch off and disconnect the Techstream.

Check For Intermittent Problems

CHECK FOR INTERMITTENT PROBLEMS

CHECK FOR INTERMITTENT PROBLEMS

HINT:

A momentary interruption (open circuit) in the connectors and/or wire harness between the sensors and ECUs can be detected using the Data List function of the Techstream.

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Follow the directions on the Techstream to display the Data List and select areas where momentary interruption should be monitored.

HINT:

• A momentary interruption (open circuit) cannot be detected for 3 seconds after the engine switch is turned on (IG) (initial check).
• If Error remains displayed for one of the items on the Techstream, check for continuity between the ECU and the item for which Error is displayed.
• If a momentary interruption occurs and Error is displayed on the Techstream, Error will remain displayed on the Techstream for 1 second after the circuit returns to normal.

(f) While observing the screen, gently jiggle the connector or wire harness between the ECU and sensors, or between ECUs.

OK:

Normal is displayed.

HINT:

If the display changes, this indicates that there has been a momentary interruption (open circuit) in the connector and/or wire harness. In this case, repair or replace the connectors and/or wire harnesses as one of them is faulty.