Lexus ES: Power Supply Drive Circuit (C1257)
DESCRIPTION
The skid control ECU (brake booster with master cylinder assembly) detects a drop in accumulator pressure according to the signals from the accumulator pressure sensor, then operates and stops the motor relay as well as the pump motor.
The skid control ECU (brake booster with master cylinder assembly) troubleshoots the built-in motor relay drive circuit, and stores this DTC when a malfunction is detected.
| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | MIL | Note |
|---|---|---|---|---|---|---|
| C1257 | Power Supply Drive Circuit | 361 362 |
| Skid control ECU (brake booster with master cylinder assembly) | Does not come on | Electronically controlled brake system DTC |
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) Check if the same DTC is output.
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| Result | Proceed to |
|---|---|
| DTC C1257 is output. | A |
| DTCs C1241, C1242 and/or C1253 are output. | B |
| A | .gif) | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
| B | | REPAIR CIRCUITS INDICATED BY OUTPUT DTCS |
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