Lexus ES: Servo Pressure Sensor Zero Point Malfunction (C14C3)
DESCRIPTION
The Servo pressure sensor detects and outputs the brake fluid pressure generated in the wheel cylinder according to the vehicle condition to the skid control ECU (brake booster with master cylinder assembly).
| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | MIL | Note |
|---|---|---|---|---|---|---|
| C14C3 | Servo Pressure Sensor Zero Point Malfunction | 424 | When the brake pedal is not depressed, the servo pressure sensor output value is -0.63 MPa (-6.4 kgf/cm2, -91.4 psi) or less or 1.53 MPa (15.6 kgf/cm2, 222 psi) or more for 3 seconds or more. | Skid control ECU (brake booster with master cylinder assembly) | Comes on |
|
MONITOR DESCRIPTION
When the brake pedal is not operated and the servo pressure sensor output value exceeds a specific value, or the value is less than a specific value for a certain amount of time, the skid control ECU (brake booster with master cylinder assembly) judges that the zero point of the servo pressure sensor is abnormal and illuminates the MIL and stores this DTC.
MONITOR STRATEGY
| Related DTCs | C14C3: Servo pressure sensor exceeded learning limit |
| Required Sensors/Components(Main) | Brake actuator (brake booster with master cylinder assembly) |
| Required Sensors/Components(Related) | Brake pedal stroke sensor assembly Brake actuator (brake booster with master cylinder assembly) Stop light switch assembly |
| Frequency of Operation | Continuous |
| Duration | 3 seconds |
| MIL Operation | Immediately |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever the following DTCs are not stored | C0562 (Brake pedal stroke sensor assembly voltage circuit/open) C124B (Brake pedal stroke sensor assembly invalid data) C14B0 (Reaction force pressure sensor voltage circuit check) C14B1 (Reaction force pressure sensor lost communication) C14B2 (Reaction force pressure sensor internal malfunction) C14B3 (Reaction force pressure sensor exceeded learning limit) C14B4 (Reaction force pressure sensor intermittent/erratic) C14B5 (Reaction force pressure sensor invalid data) C14C0 (Servo pressure sensor voltage circuit check) C14C1 (Servo pressure sensor lost communication) C14C2 (Servo pressure sensor internal malfunction) C14C4 (Servo pressure sensor intermittent/erratic) C14C5 (Servo pressure sensor invalid data) P057C, P05DD (Brake pedal stroke sensor assembly open circuit) P057D, P05DE (Brake pedal stroke sensor assembly circuit high) P057E, P05DF (Brake pedal stroke sensor assembly intermittent/erratic) P05E0 (Brake pedal stroke sensor assembly "1"/"2" correlation) |
| All of the following conditions are met | - |
| Servo pressure sensor circuit fail | Not detected |
| Brake pedal stroke sensor assembly circuit fail | Not detected |
| Reaction force pressure sensor circuit fail | Not detected |
| Brake | Off |
TYPICAL MALFUNCTION THRESHOLDS
| Servo pressure sensor | Less than -0.63 MPa (-6.4 kgf/cm2, -91.4 psi), or higher than 1.53 MPa (15.6 kgf/cm2, 222 psi) |
COMPONENT OPERATING RANGE
| All of the following conditions are met | - |
| Servo pressure sensor circuit fail | Not detected |
| Brake pedal stroke sensor assembly circuit fail | Not detected |
| Reaction force pressure sensor circuit fail | Not detected |
| Brake | Off |
| Servo pressure sensor | -0.63 MPa (-6.4 kgf/cm2, -91.4 psi) or more, and 1.53 MPa (15.6 kgf/cm2, 222 psi) or less |
CONFIRMATION DRIVING PATTERN
- Connect the Techstream to the DLC3.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Wait 3 seconds.
- Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
-
Read the DTCs.
HINT:
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
-
If the DTCs are not output, perform a universal trip and check for permanent DTCs.
Click here
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HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTCs are output, the system is normal.
CAUTION / NOTICE / HINT
NOTICE:
After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".
Click here
PROCEDURE
| 1. | READ VALUE USING TECHSTREAM (SERVO PRESSURE) |
(a) Select the Data List on the Techstream.
Click here
| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| Servo Pressure | Pressure value of servo | Min.: 0.00 MPa, Max.: 24.48 MPa | Brake pedal released: 0.00 to 2.10 MPa | Brake pedal is being depressed: Changes in proportion to the depression force of the brake pedal |
| Tester Display |
|---|
| Servo Pressure |
(b) Check that the servo pressure sensor output value is within 0.00 to 1.53 MPa when the brake pedal not depressed.
OK:
The servo pressure sensor output value is within 0.00 to 1.53 MPa.
HINT:
If the servo pressure sensor output value is within 0.00 to 1.53 MPa, the skid control ECU (brake booster with master cylinder assembly) automatically performs zero point calibration every time the power switch is turned on (IG).
Therefore, if the servo pressure sensor output value is not within 0.00 to 1.53 MPa, replace the skid control ECU (brake booster with master cylinder assembly) with a new one.
| NG |  | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
|
| 2. | RECONFIRM DTC |
(a) Clear the DTCs.
Click here
(b) Turn the power switch off.
(c) Turn the power switch on (IG).
(d) Check if the same DTC is output.
Click here
HINT:
Even if the DTC is cleared, it will immediately be output again if the servo pressure sensor zero point malfunction remains.
| Result | Proceed to |
|---|---|
| DTC C14C3 is not output. | A |
| DTC C14C3 is output. | B |
| A | | USE SIMULATION METHOD TO CHECK |
| B | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
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Installation
INSTALLATION CAUTION / NOTICE / HINT HINT:
Use the same procedure for the RH side and LH side.
The following procedure is for the LH side.
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