Lexus NX: Master Reservoir Level Malfunction (C1202)
DESCRIPTION
When a fluid level drop in the brake master cylinder reservoir assembly is detected, a signal is sent to the skid control ECU (brake booster with master cylinder assembly).
If a DTC for the fluid level drop is stored, the warning will be canceled and the DTC will be cleared when the fluid level returns to normal.
| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | Note |
|---|---|---|---|---|---|
| C1202 | Master Reservoir Level Malfunction | 371 - |
|
| - |
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
When replacing the skid control ECU (brake booster with master cylinder assembly), perform initialization and calibration of the linear solenoid valve.
Click here .gif)
HINT:
Before releasing the parking brake, chock the wheels for safety.
PROCEDURE
| 1. | CHECK BRAKE FLUID LEVEL |
(a) Check that the brake fluid level is sufficient.
OK:
Brake fluid level is sufficient.
HINT:
If the fluid level is low, check for fluid leaks, and repair as necessary.
(1) Check for brake fluid leaks (connection between the brake booster pump assembly, brake master cylinder reservoir assembly and brake booster with master cylinder assembly, and the brake booster with master cylinder assembly and wheel cylinders).
HINT:
If no leaks exist, add and adjust fluid using the Techstream.
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(2) Check that the DTC is not output again.
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(b) Check that there are no leaks from the connections between the brake booster pump assembly and brake booster with master cylinder assembly.
HINT:
As a visual check is very difficult, perform the check with the following procedure.
(1) Bleed the air from the brake system.
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(2) Connect the Techstream to the DLC3.
(3) Turn the power switch on (IG).
(4) Select the Data List on the Techstream.
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| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| Accumulator Sensor | Accumulator pressure sensor | Min.: 0.00 V, Max.: 5.00 V | Specified value: 2.90 to 4.20 V | When brake fluid is stored in the accumulator: Accumulator pressure changes in accordance with volume of fluid stored in the accumulator |
| Tester Display |
|---|
| Accumulator Sensor |
(5) Depress the brake pedal 4 or 5 times to operate the pump motor.
(6) Wait for 30 seconds without depressing the brake pedal.
(7) Check that the accumulator pressure sensor output value change is within the specified range.
OK:
Accumulator pressure sensor output value change is less than 0.55 V.
| NG | .gif) | CHECK AND REPAIR BRAKE FLUID LEAKS OR ADD FLUID |
|
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| 2. | INSPECT BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY |
| (a) Turn the power switch off. |
|
(b) Remove the reservoir filler cap.
(c) Make sure that there is no looseness at the locking part and the connecting part of the connector.
(d) Disconnect the A6 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.
(e) Measure the resistance according to the value(s) in the table below.
HINT:
A float is located inside the reservoir. Its position changes according to the level of brake fluid.
Standard Resistance:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| 1 (+) - 2 (E) | Brake fluid level warning switch off (float up) | 1.84 to 2.16 kΩ |
| 1 (+) - 2 (E) | Brake fluid level warning switch on (float down) | Below 1 Ω |
| NG | | REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY |
|
| 3. | CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY) |
(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.
(b) Disconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A57-36 (LBL) - A6-1 (+) | Always | Below 1 Ω |
| A57-36 (LBL) or A6-1 (+) - Body ground | Always | 10 kΩ or higher |
| A6-2 (E) - Body ground | Always | Below 1 Ω |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. | INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SWITCH INPUT) |
| (a) Reconnect the A57 skid control ECU (brake booster with master cylinder assembly) connector. |
|
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| A6-1 (+) - Body ground | Power switch on (IG) | 11 to 14 V |
| NG | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
|
| 5. | CHECK BRAKE DISC |
(a) Turn the power switch off.
(b) Reconnect the A6 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.
(c) Disconnect the A53 brake pedal stroke sensor assembly connector.
(d) Perform a road test according to Freeze Frame Data or customer problem analysis. While driving, check for abnormal brake pedal vibration caused by brake discs that are worn or have excess runout.
OK:
Brake pedal does not vibrate during braking.
HINT:
- An unevenly worn disc may vibrate the caliper pistons and cause fluctuations in brake line pressure, triggering a malfunction detection condition.
- The brake pedal does not kick back due to caliper piston vibration during electronically controlled brake system control.
- If the brake pedal stroke sensor assembly connector is disconnected, the fail-safe function will prohibit electronically controlled brake system control.
- The Active Test does not prohibit electronically controlled brake system control when the vehicle is being driven, so disconnect the brake pedal stroke sensor assembly connector before continuing with inspection.
-
Uneven disc wear can be checked by measuring the disc thickness variation.
for Front Brake: Click here
for Rear Brake: Click here
| NG | | REPLACE BRAKE DISC |
|
| 6. | RECONFIRM DTC |
(a) Reconnect the A53 brake pedal stroke sensor assembly connector.
(b) Clear the DTCs.
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(c) Turn the power switch on (READY).
(d) Perform a road test.
(e) Check if the same DTC is output.
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| Result | Proceed to |
|---|---|
| DTC C1202 is not output. | A |
| DTC C1202 is output. | B |
HINT:
If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step.
Click here
| A | | USE SIMULATION METHOD TO CHECK |
| B | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
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