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:
Inspection
INSPECTION
PROCEDURE
1. INSPECT FUEL PUMP
(a) Inspect the resistance of the fuel pump.
(1) Measure the resistance according to the value(s) in the table below.
Text in Illustration
*a
Component without harness connected
(Fuel Pump)
...
Low Output Signal of Rear Speed Sensor RH (Test Mode DTC) (C1273,C1274,C1403,C1404)
DESCRIPTION
Refer to DTCs C1401 and C1402 (See page ).
DTC Code
DTC Detection Condition
Trouble Area
C1273
C1274
Stored only during test mode.
Rear speed sensor RH/LH
Rear speed sensor rotor RH/LH (rear ax ...
Pattern Select Switch Power Mode Circuit
DESCRIPTION
The ECM memory contains the programs for the normal and PWR shift patterns.
By following the programs corresponding to the signals from the pattern select
switch assembly, park/neutral position switch and other various sensors, the ECM
switches the shift solenoid valves on and off, ...
