Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Diagnosis System

DIAGNOSIS SYSTEM

DESCRIPTION

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

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

To check the DTCs, connect the Techstream to the DLC3 on the vehicle. The Techstream enables you to clear the DTCs, activate the 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.

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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 or slip indicator light).

(b) The DTCs are simultaneously stored in memory. The DTCs can be read by connecting the Techstream.

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(c) This system has a Dealer Mode (Signal Check) function.

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WARNING LIGHT AND INDICATOR LIGHT INITIAL CHECK

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