Toyota Tacoma (2015-2018) Service Manual: Power Supply Drive Circuit (C1257)
DESCRIPTION
The motor relay (semiconductor relay) is built into the hydraulic brake booster and drives the pump motor based on a signal from the skid control ECU (master cylinder solenoid).
|
DTC No. |
DTC Detecting Condition |
Trouble Areas |
|---|---|---|
|
C1257 |
Open in pump motor input circuit |
Hydraulic brake booster pump motor circuit |
PROCEDURE
|
1. |
CHECK HYDRAULIC BRAKE BOOSTER PUMP MOTOR OPERATION |
(a) Turn the ignition switch to OFF.
(b) Disconnect the actuator connector (S1).
(c) Depress the brake pedal more than 20 times.
(d) Turn the ignition switch to the ON position.
(e) Check the hydraulic brake booster pump motor operation.
OK:
Hydraulic brake booster pump operates.
| NG | .gif) |
REPLACE MASTER CYLINDER SOLENOID |
|
.gif)
|
2. |
RECONFIRM DTC |
(a) Turn the ignition switch to OFF.
(b) Reconnect the actuator connector (S1).
(c) Turn the ignition switch to the ON position.
(d) Clear the DTCs (See page .gif)
).
(e) Check if the same DTCs are recorded.
|
Result |
Proceed to |
|---|---|
|
DTC output |
A |
|
DTC not output |
B |
| A | |
REPLACE MASTER CYLINDER SOLENOID |
| B | |
END |
Accumulator Low Pressure (C1256)
DESCRIPTION
The accumulator pressure sensor is connected to the skid control ECU in the master
cylinder solenoid.
DTC No.
DTC Detecting Condition
Trouble Areas
...
Transfer L4 Position Switch Circuit (C1268)
DESCRIPTION
A-TRAC is activated if wheel skid is detected while the transfer is in the L4
position.
DTC Code
DTC Detecting Condition
Trouble Areas
...
Other materials:
High Power Supply Voltage Malfunction (C1417)
DESCRIPTION
If a malfunction is detected in the power supply circuit, the skid control ECU
(housed in the master cylinder solenoid) stores this DTC and the fail-safe function
prohibits ABS/VSC/TRAC operation.
This DTC is stored when the IG1 terminal voltage deviates from the DTC detection
co ...
ECM Communication Circuit Malfunction (C1203)
DESCRIPTION
The circuit is used to send TRAC and VSC control information from the skid control
ECU (brake actuator assembly) to the ECM, and engine control information from the
ECM to the skid control ECU (brake actuator assembly) through the CAN communication
system.
for 4WD or w/ Rear Diff ...
Diagnostic Trouble Code Chart
DIAGNOSTIC TROUBLE CODE CHART
If a trouble code is indicated while checking DTCs, inspect the circuit listed
for that code in the table below, and proceed to the applicable page.
Cruise Control System
DTC Code
Detection Item
MIL
See page
...
