Lexus NX: 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 booster with master cylinder assembly).
The skid control ECU (brake booster with master cylinder 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 auxiliary battery voltage.
Standard voltage:
11 to 14 V
If the voltage is below 11 V, recharge the auxiliary battery before proceeding to the next step.
(b) Check the DLC3.
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DIAGNOSIS
(a) If the skid control ECU (brake booster with master cylinder assembly) detects a malfunction, the ABS warning, brake warning / red (malfunction), brake warning / yellow (minor malfunction) and slip indicator lights will come on in order to warn the driver. Also, if the vehicle is under the following conditions and the brake hold switch (integration control and panel assembly) is turned on, the brake hold operated indicator light blinks.
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Vehicle Conditions:
- The driver's door is closed.
- Driver's seat belt is fastened.
(b) The DTCs are simultaneously stored in the memory.
The DTCs can be read by connecting the GTS.
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(c) This system has a Test Mode (signal check) function.
The Test Mode DTCs can be read by connecting the GTS.
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WARNING LIGHT AND INDICATOR LIGHT INITIAL CHECK
(a) When the power switch is turned on (IG), check that the VSC OFF indicator light comes on for approximately 3 seconds, and ABS warning, brake warning / red (malfunction), brake warning / yellow (minor malfunction), slip indicator, brake hold standby indicator and brake hold operated indicator lights come on until the power switch is turned on (READY).
HINT:
- When the brake fluid level is low, the brake warning light / red (malfunction) comes on.
- If the warning light and indicator light check results are not normal, proceed to troubleshooting for the ABS warning, brake warning / red (malfunction), brake warning / yellow (minor malfunction), slip indicator, brake hold standby indicator and brake hold operated indicator light circuits.
- If an indicator remains on or does not come on, proceed to troubleshooting for the light circuits listed below.
| Trouble Area | See Procedure |
|---|---|
| ABS warning light circuit (Remains on) | |
| ABS warning light circuit (Does not come on) | |
| Brake warning light / red (malfunction) circuit (Remains on) | |
| Brake warning light / red (malfunction) circuit (Does not come on) | |
| Brake warning light / yellow (minor malfunction) circuit (Remains on) | |
| Brake warning light / yellow (minor malfunction) circuit (Does not come on) | |
| Slip indicator light circuit (Remains on) | |
| Slip indicator light circuit (Does not come on) | |
| Brake hold standby indicator light circuit | |
| Brake hold operated indicator light circuit | |
READ NEXT:
Dtc Check / Clear
DTC CHECK / CLEAR DTC CHECK/CLEAR (a) Check for DTCs. (1) Connect the Techstream to the DLC3. (2) Turn the power switch on (IG). (3) Turn the Techstream on. (4) Read the DTCs following the prompts on
Freeze Frame Data
FREEZE FRAME DATA FREEZE FRAME DATA/INFORMATION (a) Using the Techstream, check the vehicle condition (ECU, sensor) when the brake system operates or a DTC is output. (b) The freeze frame data that is
Fail-safe Chart
FAIL-SAFE CHART FAIL-SAFE FUNCTION OF CONTROL SYSTEM (a) When a malfunction is detected in the brake control system, the skid control ECU (brake booster with master cylinder assembly) turns the ABS wa
SEE MORE:
Problem Symptoms Table
PROBLEM SYMPTOMS TABLE HINT: 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
Operation Check
OPERATION CHECK CHECK NAVIGATION SYSTEM NORMAL CONDITION (a) If the cause of a symptom is any of the following, the corresponding symptom is normal; it is not a malfunction. Symptom Answer A longer route than expected is chosen. Depending on the road conditions, the navigation ECU may det
