Toyota Tacoma (2015-2018) Service Manual: Open in Pump Motor Circuit (C1251)
DESCRIPTION
The motor relay (semiconductor relay) is built into the master cylinder solenoid and drives the pump motor based on a signal from the skid control ECU (master cylinder solenoid).
|
DTC No. |
DTC Detecting Condition |
Trouble Areas |
|---|---|---|
|
C1251 |
Open in motor system circuit (motor input circuit) |
Hydraulic brake booster pump motor circuit |
WIRING DIAGRAM
CAUTION / NOTICE / HINT
HINT:
Remove the hydraulic brake booster before the inspection (See page
.gif)
).
PROCEDURE
|
1. |
CHECK BRAKE PUMP MOTOR WIRE HARNESS CONNECTION (MT+ / MT-) |
(a) Using a screwdriver, remove the 2 plugs from the hydraulic brake booster
(See page ).
(b) Check the tightening torque of 2 screws which fasten the wire harness connecting
hydraulic brake booster and brake booster pump (See page
).
Torque:
2.9 N·m {30 kgf·cm, 26 in·lbf}
| NG | .gif) |
RETIGHTEN SCREWS |
|
.gif)
|
2. |
CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS (MT+/MT-) |
|
(a) Using a screwdriver, remove the 2 screws and pull the wire harness from the hydraulic brake booster. |
|
(b) Measure the resistance between the red wire (MT+) and black wire (MT-).
Resistance:
2 Ω
| NG | |
REPLACE HYDRAULIC BRAKE BOOSTER |
|
|
3. |
RECONFIRM DTC |
(a) Reassemble the hydraulic brake booster, then reinstall the hydraulic brake booster.
(b) Clear the DTCs (See page
).
(c) Check if the same DTCs are detected.
|
Result |
Proceed to |
|---|---|
|
DTC output |
A |
|
DTC not output |
B |
| A | |
REPLACE MASTER CYLINDER SOLENOID |
| B | |
END |
Open Circuit in IG1/IG2 Power Source Circuit (C1242)
DESCRIPTION
If there is a problem with the skid control ECU (master cylinder solenoid) power
supply circuit, the skid control ECU outputs the DTC and prohibits operation under
the fail safe funct ...
Brake Booster Pump Motor on Time Abnormally Long (C1252)
DESCRIPTION
The motor relay (semiconductor relay) is built into the master cylinder solenoid
and drives the pump motor based on a signal from the skid control ECU (master cylinder
solenoid).
...
Other materials:
Problem Symptoms Table
PROBLEM SYMPTOMS TABLE
HINT:
Use the table below to help determine the cause of problem symptoms.
If multiple suspected areas are listed, the potential causes of the symptoms
are listed in order of probability in the "Suspected Area" column of the
table. Check each sy ...
Operation Check
OPERATION CHECK
INPUT SIGNAL CHECK
*a
+RES
*b
-SET
*c
ON-OFF
*d
CANCEL
(a) Connect the Techstream to the DLC3.
(b) Check the cruise control main switch using the Data List functio ...
Disassembly
DISASSEMBLY
PROCEDURE
1. REMOVE OIL PUMP RELIEF VALVE
(a) Using a 27 mm socket wrench, remove the oil pump relief valve plug.
(b) Remove the oil pump relief valve spring and oil pump relief valve.
(c) Remove the spring and relief valve.
2. R ...
