Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Diagnosis System

DIAGNOSIS SYSTEM

DESCRIPTION

When troubleshooting a vehicle with a diagnosis system, the only difference from the usual troubleshooting procedure is connecting the Techstream to the vehicle and reading various data output from the skid control ECU (brake actuator assembly).

The skid control ECU (brake actuator assembly) records DTCs when it detects a malfunction in itself or in its circuits.

To check for DTCs, connect the Techstream to the DLC3 on the vehicle. The Techstream can be used to clear the DTCs, activate various actuators, and check the Freeze Frame Data and Data List.

(a) Check the battery voltage.

Standard Voltage:

11 to 14 V

If the voltage is below 11 V, recharge the battery before proceeding to the next step.

(b) Check the DLC3.

Click here

DIAGNOSIS

(a) If a malfunction occurs in one part of the system, the skid control ECU (brake actuator assembly) illuminates the warning light corresponding to the malfunctioning system (ABS warning light, brake system warning light (red indicator) or slip indicator light).

(b) If a DTC is stored by the skid control ECU (brake actuator assembly) and the following conditions are met when the brake hold switch (electric parking brake switch assembly) is pressed, the brake hold operated indicator light blinks.

• Vehicle Conditions:
  1. The driver door is closed.
  2. The driver seat belt is fastened.

(c) DTCs are simultaneously stored in memory.

The DTCs can be read by connecting the Techstream.

Click here

(d) This system has a Test Mode (Signal Check) function.

Click here

WARNING LIGHT AND INDICATOR LIGHT INITIAL CHECK

(a) When the engine switch is turned on (IG), check that the ABS warning light, brake system warning light (red indicator), VSC OFF indicator light, brake hold standby indicator light, brake hold operated indicator light and slip indicator light come on for approximately 3 seconds.

HINT:

• When the brake fluid level is low or the vacuum inside the brake booster decreases, the brake system warning light (red indicator) comes on.
• If the warning light and indicator light check result is not normal, proceed to troubleshooting for the ABS warning light, brake system warning light (red indicator), VSC OFF indicator light, slip indicator light, brake hold standby indicator light and brake hold operated indicator light circuits.
• If any of the indicators remains on or does not come on, proceed to troubleshooting for the light circuits listed below.