Lexus NX: Problem Symptoms Table
PROBLEM SYMPTOMS TABLE
If there are no DTCs but the problem still occurs, check the suspected areas for each problem symptom in the order given in the table below and proceed to the relevant troubleshooting page.
NOTICE:
When replacing the skid control ECU (brake booster with master cylinder assembly), sensors, etc., make sure that the power switch is turned off, the stop light switch assembly is off, and 2 minutes have elapsed since the driver door was closed.
HINT:
- Since the hydraulic passage is blocked off by the master cut solenoid during electronically controlled brake system control, there are no kickbacks (vibrations) to the brake pedal, creating little sound even while the ABS is operating.
- 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.
| Symptom | Suspected Area | Link |
|---|---|---|
| ABS, BA and/or EBD does not operate | Use a chassis dynamometer, etc. to check the electronically controlled brake system operation. | - |
| Check again to see if DTCs are output. (If DTCs are output, perform diagnosis based on the DTCs that are output.) | | |
| Power source circuit | | |
| Front speed sensor circuit | | |
| Rear speed sensor circuit | | |
| Check the brake actuator (brake booster with master cylinder assembly) using the Techstream. (Check brake actuator (brake booster with master cylinder assembly) operation using the Active Test function.) If abnormal, check the hydraulic circuit for leaks. | | |
| If the symptoms still occur even after the above suspected areas have been inspected and proved to be normal, replace the skid control ECU (brake booster with master cylinder assembly). | | |
| ABS, BA and/or EBD does not operate efficiently | Check again to see if DTCs are output. (If DTCs are output, perform diagnosis based on the DTCs that are output.) | |
| Front speed sensor circuit | | |
| Rear speed sensor circuit | | |
| Check the brake actuator (brake booster with master cylinder assembly) using the Techstream. (Check brake actuator (brake booster with master cylinder assembly) operation using the Active Test function.) If abnormal, check the hydraulic circuit for leaks. | | |
| If the symptoms still occur even after the above suspected areas have been inspected and proved to be normal, replace the skid control ECU (brake booster with master cylinder assembly). | | |
| ABS warning light abnormal (Remains on) | ABS warning light circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| ABS warning light abnormal (Does not come on) | ABS warning light circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Brake warning light / red (malfunction) abnormal (Remains on) | Brake fluid level warning switch circuit | |
| Brake warning light / red (malfunction) circuit | | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Brake warning light / red (malfunction) abnormal (Does not come on) | Brake warning light / red (malfunction) circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| VSC and/or TRAC does not operate | Check again to see if DTCs are output. (If DTCs are output, perform diagnosis based on the DTCs that are output.) | |
| Power source circuit | | |
| Check the hydraulic circuit for leaks. | - | |
| Front speed sensor circuit | | |
| Rear speed sensor circuit | | |
| Yaw rate and acceleration sensor circuit | | |
| Steering sensor circuit | | |
| If the symptoms still occur even after the above suspected areas have been inspected and proved to be normal, replace the skid control ECU (brake booster with master cylinder assembly). | | |
| Brake warning light / yellow (minor malfunction) abnormal (Remains on) | Brake warning light / yellow (minor malfunction) circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Brake warning light / yellow (minor malfunction) abnormal (Does not come on) | Brake warning light / yellow (minor malfunction) circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Slip indicator light abnormal (Remains on) | Slip indicator light circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Slip indicator light abnormal (Does not come on) | Slip indicator light circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| VSC OFF switch (Integration control and panel assembly) abnormal | VSC OFF switch (Integration control and panel assembly) circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Brake hold standby indicator light abnormal | Brake hold operated conditions are not met | |
| Brake hold standby indicator light circuit | | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| Brake hold operated indicator light abnormal | Brake hold operated conditions are not met | |
| Brake hold operated indicator light circuit | | |
| Skid control ECU (Brake booster with master cylinder assembly) | | |
| DTC check cannot be done | Check again to see if DTCs are output. (If DTCs are output, perform diagnosis based on the DTCs that are output.) | |
| If the symptoms still occur even after the above suspected areas have been inspected and proved to be normal, replace the skid control ECU (brake booster with master cylinder assembly). | | |
| Sensor check cannot be done | Skid control ECU (Brake booster with master cylinder assembly) | |
| Meter buzzer abnormal | Meter buzzer circuit | |
| Skid control ECU (Brake booster with master cylinder assembly) | |
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Terminals Of Ecu
TERMINALS OF ECU TERMINALS OF ECU *a Component without harness connected (Skid Control ECU (Brake Booster with Master Cylinder Assembly)) - - Terminal No. (Symbol) Terminal Descripti
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 readin
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
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Parts Location
PARTS LOCATION ILLUSTRATION *1 NO. 1 ENGINE ROOM RELAY BLOCK - IG2-MAIN RELAY *2 NO. 2 ENGINE ROOM RELAY BLOCK - IG1 RELAY *3 SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - - ILLUSTRATION *1 BACK DOOR SWITCH ASSEMBLY *2 DOOR CONTROL RECEIVER *3
Operation Check
OPERATION CHECK CHECK WIRELESS CHARGING SYSTEM OPERATION (a) Turn the power switch on (ACC) or on (IG). HINT: When the wireless charging system is on and the power switch is turned off, the wireless charging system turns on the next time the power switch is turned on (ACC) or on (IG). *a Wirel
