Toyota Yaris: Vehicle Stability Control System / Brake Warning Light Remains ON
DESCRIPTION
This procedure is for troubleshooting when the brake system warning light remains on but no DTCs are output.
The skid control ECU (brake actuator assembly) controls the brake system warning light in the combination meter assembly via CAN communication.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
-
After replacing the skid control ECU (brake actuator assembly), perform "Calibration".
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- Before performing this procedure, depress the brake pedal and confirm that the stop lights illuminate.
PROCEDURE
| 1. | PRE-CHECK |
(a) Check that all of the following conditions required for the brake system warning light to turn off are met:
(1) The ABS warning light is not illuminated.
HINT:
If the ABS warning light remains illuminated, make sure that the conditions required for the ABS warning light to turn off are met.
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(2) The brake fluid level in the brake master cylinder reservoir assembly is not low.
(3) The vacuum inside the brake booster decreases.
HINT:
When the vacuum inside the brake booster decreases, the brake system warning light comes on.
|
| 2. | CHECK GTS OUTPUT (CAN COMMUNICATION SYSTEM) |
(a) Operate the GTS, and check for DTCs related to the CAN communication system.
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| Result | Proceed to |
|---|---|
| Any CAN communication system relating DTCs are output | A |
| None of the above conditions are met | B |
| A |
 | INSPECT CAN COMMUNICATION SYSTEM |
|
| 3. | INSPECT BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY |
(a) With a sufficient level of brake fluid, disconnect the A24 brake fluid level warning switch (brake master cylinder reservoir assembly) connector and confirm that the brake system warning light illuminates.
OK:
The brake system warning light does not turn off.
HINT:
If the brake system warning light turns off, there is a short in the brake fluid level warning switch (brake master cylinder reservoir assembly) circuit.
| NG |
 | REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY |
|
| 4. | CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY) |
(a) Turn the ignition switch off.
(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.
OK:
The connector is securely connected.
(c) Disconnect the H7 combination meter assembly connector.
(d) Check both the connector case and the terminals for deformation and corrosion.
OK:
No deformation or corrosion.
(e) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| H7-16(SW) or A24-1 (+) - Body ground | Always | 10 kΩ or higher |
| NG |
 | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 5. | INSPECT COMBINATION METER ASSEMBLY |
(a) Reconnect the H7 combination meter assembly connector.
(b) Reconnect the A24 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.
(c) Perform the Active Test of the combination meter assembly using the GTS.
Body Electrical > Combination Meter > Active Test| Tester Display |
|---|
| Brake Warning |
(d) Check the combination meter assembly.
OK:
The brake system warning light turns on or off in accordance with GTS operation.
| OK |
 | REPLACE BRAKE ACTUATOR ASSEMBLY |
| NG |
 | INSPECT METER / GAUGE SYSTEM |
ABS Warning Light does not Come ON
DESCRIPTION The skid control ECU (brake actuator assembly) controls the ABS warning light in the combination meter assembly via CAN communication. CAUTION / NOTICE / HINT NOTICE: After replacing the skid control ECU (brake actuator assembly), perform "Calibration"...
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DESCRIPTION The skid control ECU (brake actuator assembly) controls the brake system warning light in the combination meter assembly via CAN communication...
Other information:
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Break-In Period
No special break-in is necessary, but a few precautions in the first 600 miles (1,000 km) may add to the performance, economy, and life of the vehicle.
Do not race the engine. Do not maintain one constant speed, either slow or fast, for a long period of time. Do not drive constantly at full-throttle or high engine rpm for extended periods of time. Avoid unnecessary hard stops. Avoid full-throttle starts.