Lexus ES: Accumulator Pressure Sensor Stuck (C14D5)
DESCRIPTION
The accumulator pressure sensor is built into the brake booster with master cylinder assembly and detects the accumulator pressure.
If the skid control ECU (brake booster with master cylinder assembly) detects that the accumulator pressure sensor value is below the threshold, operation of the motor relay is requested and the pump motor built into the brake booster pump assembly operates.
| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | MIL | Note |
|---|---|---|---|---|---|---|
| C14D5 | Accumulator Pressure Sensor Stuck | 334 | When the pump motor is operating, the accumulator pressure sensor signal does not change for 14 seconds or more. | Skid control ECU (brake booster with master cylinder assembly) | Comes on |
|
MONITOR DESCRIPTION
When the volume of brake fluid within the accumulator is below a certain amount, the skid control ECU (brake booster with master cylinder assembly) operates the pump motor. When the pump motor is being operated and the output value of the accumulator pressure sensor does not change substantially for a certain period of time, the skid control ECU (brake booster with master cylinder assembly) judges that the accumulator pressure sensor has a stuck malfunction and illuminates the MIL and stores this DTC.
MONITOR STRATEGY
| Related DTCs | C14D5: Accumulator pressure sensor stuck |
| Required Sensors/Components(Main) | Brake actuator (brake booster with master cylinder assembly) Brake booster pump assembly |
| Required Sensors/Components(Related) | Skid control ECU (brake booster with master cylinder assembly) Brake actuator (brake booster with master cylinder assembly) Brake booster pump assembly |
| Frequency of Operation | Continuous |
| Duration | 7 to 14 seconds (Time depends on battery voltage) |
| MIL Operation | Immediately |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever the following DTCs are not stored | C121D (Pump motor open circuit) C14C0 (Servo pressure sensor voltage circuit check) C14C1 (Servo pressure sensor lost communication) C14C2 (Servo pressure sensor internal malfunction) C14C3 (Servo pressure sensor exceeded learning limit) C14C4 (Servo pressure sensor intermittent/erratic) C14C5 (Servo pressure sensor invalid data) C14D0 (Accumulator pressure sensor voltage circuit check) C14D1 (Accumulator pressure sensor lost communication) C14D2 (Accumulator pressure sensor internal malfunction) C14D3 (Accumulator pressure sensor intermittent/erratic) C14D4 (Case 1) (Accumulator pressure sensor invalid data) C14D4 (Case 2) (Accumulator pressure sensor intermittent) |
| All of the following conditions are met | - |
| Accumulator pressure sensor fail | Not detected |
| Pump motor control circuit fail | Not detected |
| ABS/TRAC/VSC | Off |
| Accumulator pressure | 17.1 MPa (174.4 kgf/cm2, 2480 psi) or more |
| Pump motor voltage (MTT) | Less than 6 V |
| Hydraulic used by brake booster | 20 cm3 (1.2 cu.in.) or more |
| Change of accumulator pressure | Less than 0.12 MPa (1.2 kgf/cm2, 17 psi) |
TYPICAL MALFUNCTION THRESHOLDS
| Change of accumulator pressure while pump motor is intrusively operated | Less than 0.12 MPa (1.2 kgf/cm2, 17 psi) |
COMPONENT OPERATING RANGE
| All of the following conditions are met | - |
| Accumulator pressure sensor fail | Not detected |
| Accumulator pressure | Less than 20.85 MPa (212.6 kgf/cm2, 3024 psi) |
| Change of accumulator pressure | 0.12 MPa (1.2 kgf/cm2, 17 psi) or more |
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.
-
Repeat the following step 3 times.
- Fully depress the brake pedal for 2 seconds, release it and wait 1 second.
- Wait 14 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.
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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".
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PROCEDURE
| 1. | CHECK DTC |
(a) Clear the DTCs.
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(b) Turn the power switch off.
(c) Turn the power switch on (IG).
(d) Depress the brake pedal 10 times or more to operate the pump motor.
(e) After the pump motor stops, check for DTCs.
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| Result | Proceed to |
|---|---|
| DTC C14D5 is not output. | A |
| DTC C14D5 is output. | B |
| A |  | USE SIMULATION METHOD TO CHECK |
| B | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
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